The GnuTLS Manual

Copyright © 2001-2012 Free Software Foundation, Inc.

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled “GNU Free Documentation License”.

Chapter 1. Preface

This document demonstrates and explains the GnuTLS library API. A brief introduction to the protocols and the technology involved is also included so that an application programmer can better understand the GnuTLS purpose and actual offerings. Even if GnuTLS is a typical library software, it operates over several security and cryptographic protocols which require the programmer to make careful and correct usage of them. Otherwise it is likely to only obtain a false sense of security. The term of security is very broad even if restricted to computer software, and cannot be confined to a single cryptographic library. For that reason, do not consider any program secure just because it uses GnuTLS; there are several ways to compromise a program or a communication line and GnuTLS only helps with some of them.

Although this document tries to be self contained, basic network programming and public key infrastructure (PKI) knowledge is assumed in most of it. A good introduction to networking can be found in [STEVENS], to public key infrastructure in [GUTPKI] and to security engineering in [ANDERSON].

Updated versions of the GnuTLS software and this document will be available from http://www.gnutls.org/ and http://www.gnu.org/software/gnutls/.

Chapter 2. Introduction to GnuTLS

In brief GnuTLS can be described as a library which offers an API to access secure communication protocols. These protocols provide privacy over insecure lines, and were designed to prevent eavesdropping, tampering, or message forgery.

Technically GnuTLS is a portable ANSI C based library which implements the protocols ranging from SSL 3.0 to TLS 1.2 (see Introduction to TLS, for a detailed description of the protocols), accompanied with the required framework for authentication and public key infrastructure. Important features of the GnuTLS library include:

Support for TLS 1.2, TLS 1.1, TLS 1.0 and SSL 3.0 protocols.

Support for Datagram TLS 1.0.

Support for handling and verification of X.509 and OpenPGP certificates.

Support for password authentication using TLS-SRP.

Support for keyed authentication using TLS-PSK.

Support for PKCS #11 tokens and smart-cards.

The GnuTLS library consists of three independent parts, namely the “TLS protocol part”, the “Certificate part”, and the “Cryptographic back-end” part. The “TLS protocol part” is the actual protocol implementation, and is entirely implemented within the GnuTLS library. The “Certificate part” consists of the certificate parsing, and verification functions and it uses functionality from the libtasn1[1] library. The “Cryptographic back-end” is provided by the nettle[2] library.

Downloading and installing

GnuTLS is available for download at: http://www.gnutls.org/download.html

GnuTLS uses a development cycle where even minor version numbers indicate a stable release and a odd minor version number indicate a development release. For example, GnuTLS 1.6.3 denote a stable release since 6 is even, and GnuTLS 1.7.11 denote a development release since 7 is odd.

GnuTLS depends on Libnettle, and you will need to install it before installing GnuTLS. Libnettle is available from http://www.lysator.liu.se/~nisse/nettle/. Don’t forget to verify the cryptographic signature after downloading source code packages.

The package is then extracted, configured and built like many other packages that use Autoconf. For detailed information on configuring and building it, refer to the INSTALL file that is part of the distribution archive. Typically you invoke ./configure and then make check install. There are a number of compile-time parameters, as discussed below.

The compression library, libz, as well as p11-kit are a optional dependencies. You can get libz from http://www.zlib.net/ and p11-kit from http://p11-glue.freedesktop.org/.

The X.509 part of GnuTLS needs ASN.1 functionality, from a library called libtasn1. A copy of libtasn1 is included in GnuTLS. If you want to install it separately (e.g., to make it possibly to use libtasn1 in other programs), you can get it from http://www.gnu.org/software/gnutls/download.html.

A few configure options may be relevant, summarized below. They disable or enable particular features, to create a smaller library with only the required features. Note however, that although a smaller library is generated, the included programs are not guarranteed to compile if some of these options are given.

--disable-srp-authentication
--disable-psk-authentication
--disable-anon-authentication
--disable-extra-pki
--disable-openpgp-authentication
--disable-openssl-compatibility
--without-p11-kit

For the complete list, refer to the output from configure --help.

[1] http://www.gnu.org/software/libtasn1/

[2] http://www.lysator.liu.se/~nisse/nettle/

Overview

In this document we present an overview of the supported security protocols in Introduction to TLS, and continue by providing more information on the certificate authentication in Certificate authentication, and shared-key as well anonymous authentication in Shared-key and anonymous authentication. We elaborate on certificate authentication by demonstrating advanced usage of the API in More on certificate authentication. The core of the TLS library is presented in How to use GnuTLS in applications and example applications are listed in GnuTLS application examples. In Other included programs the usage of few included programs that may assist debugging is presented. The last chapter is Internal architecture of GnuTLS that provides a short introduction to GnuTLS’ internal architecture.

Chapter 3. Introduction to TLS and DTLS

TLS stands for “Transport Layer Security” and is the successor of SSL, the Secure Sockets Layer protocol [SSL3] designed by Netscape. TLS is an Internet protocol, defined by IETF[3], described in [RFC5246]. The protocol provides confidentiality, and authentication layers over any reliable transport layer. The description, above, refers to TLS 1.0 but applies to all other TLS versions as the differences between the protocols are not major.

The DTLS protocol, or “Datagram TLS” [RFC4347] is a protocol with identical goals as TLS, but can operate under unreliable transport layers such as UDP. The discussions below apply to this protocol as well, except when noted otherwise.

TLS layers

TLS is a layered protocol, and consists of the record protocol, the handshake protocol and the alert protocol. The record protocol is to serve all other protocols and is above the transport layer. The record protocol offers symmetric encryption, data authenticity, and optionally compression. The alert protocol offers some signaling to the other protocols. It can help informing the peer for the cause of failures and other error conditions. See The Alert Protocol, for more information. The alert protocol is above the record protocol.

The handshake protocol is responsible for the security parameters’ negotiation, the initial key exchange and authentication. See The Handshake Protocol, for more information about the handshake protocol. The protocol layering in TLS is shown in fig:tls-layers.

[3] IETF, or Internet Engineering Task Force, is a large open international community of network designers, operators, vendors, and researchers concerned with the evolution of the Internet architecture and the smooth operation of the Internet. It is open to any interested individual.

The transport layer

TLS is not limited to any transport layer and can be used above any transport layer, as long as it is a reliable one. DTLS can be used over reliable and unreliable transport layers. GnuTLS supports TCP and UDP layers transparently using the Berkeley sockets API. However, any transport layer can be used by providing callbacks for GnuTLS to access the transport layer (for details see Setting up the transport layer).

The TLS record protocol

The record protocol is the secure communications provider. Its purpose is to encrypt, authenticate and —optionally— compress packets. The record layer functions can be called at any time after the handshake process is finished, when there is need to receive or send data. In DTLS however, due to re-transmission timers used in the handshake out-of-order handshake data might be received for some time (maximum 60 seconds) after the handshake process is finished.

The functions to access the record protocol are limited to send and receive functions, which might, given the importance of this protocol in TLS, seem awkward. This is because the record protocol’s parameters are all set by the handshake protocol. The record protocol initially starts with NULL parameters, which means no encryption, and no MAC is used. Encryption and authentication begin just after the handshake protocol has finished.

Encryption algorithms used in the record layer

Confidentiality in the record layer is achieved by using symmetric block encryption algorithms like 3DES, AES or stream algorithms like ARCFOUR_128. Ciphers are encryption algorithms that use a single, secret, key to encrypt and decrypt data. Block algorithms in CBC mode also provide protection against statistical analysis of the data. Thus, if you’re using the TLS protocol, a random number of blocks will be appended to data, to prevent eavesdroppers from guessing the actual data size.

The supported in GnuTLS ciphers and MAC algorithms are shown in tab:ciphers and tab:macs.

Algorithm

Description

3DES_CBC

This is the DES block cipher algorithm used with triple encryption (EDE). Has 64 bits block size and is used in CBC mode.

ARCFOUR_128

ARCFOUR_128 is a compatible algorithm with RSA’s RC4 algorithm, which is considered to be a trade secret. It is a fast cipher but considered weak today.

ARCFOUR_40

This is the ARCFOUR cipher fed with a 40 bit key, which is considered weak.

AES_CBC

AES or RIJNDAEL is the block cipher algorithm that replaces the old DES algorithm. Has 128 bits block size and is used in CBC mode.

AES_GCM

This is the AES algorithm in the authenticated encryption GCM mode. This mode combines message authentication and encryption and can be extremely fast on CPUs that support hardware acceleration.

CAMELLIA_CBC

This is an 128-bit block cipher developed by Mitsubishi and NTT. It is one of the approved ciphers of the European NESSIE and Japanese CRYPTREC projects.

Algorithm

Description

MAC_MD5

This is an HMAC based on MD5 a cryptographic hash algorithm designed by Ron Rivest. Outputs 128 bits of data.

MAC_SHA1

An HMAC based on the SHA1 cryptographic hash algorithm designed by NSA. Outputs 160 bits of data.

MAC_SHA256

An HMAC based on SHA256. Outputs 256 bits of data.

MAC_AEAD

This indicates that an authenticated encryption algorithm, such as GCM, is in use.

Compression algorithms used in the record layer

The TLS record layer also supports compression. The algorithms implemented in GnuTLS can be found in the table below. The included algorithms perform really good when text, or other compressible data are to be transferred, but offer nothing on already compressed data, such as compressed images, zipped archives etc. These compression algorithms, may be useful in high bandwidth TLS tunnels, and in cases where network usage has to be minimized. It should be noted however that compression increases latency.

The record layer compression in GnuTLS is implemented based on [RFC3749]. The supported algorithms are shown below.

GNUTLS_COMP_UNKNOWN

Unknown compression method.

GNUTLS_COMP_NULL

The NULL compression method (no compression).

GNUTLS_COMP_DEFLATE

The DEFLATE compression method from zlib.

GNUTLS_COMP_ZLIB

Same as GNUTLS_COMP_DEFLATE .

Weaknesses and countermeasures

Some weaknesses that may affect the security of the record layer have been found in TLS 1.0 protocol. These weaknesses can be exploited by active attackers, and exploit the facts that

TLS has separate alerts for “decryption_failed” and “bad_record_mac”

The decryption failure reason can be detected by timing the response time.

The IV for CBC encrypted packets is the last block of the previous encrypted packet.

Those weaknesses were solved in TLS 1.1 [RFC4346] which is implemented in GnuTLS. For this reason we suggest to always negotiate the highest supported TLS version with the peer[4]. For a detailed discussion of the issues see the archives of the TLS Working Group mailing list and [CBCATT].

On record padding

The TLS protocol allows for random padding of records in CBC ciphers, to prevent statistical analysis based on the length of exchanged messages (see [RFC5246] section 6.2.3.2). GnuTLS appears to be one of few implementation that take advantage of this text, and pad records by a random length.

The TLS implementation in the Symbian operating system, frequently used by Nokia and Sony-Ericsson mobile phones, cannot handle non-minimal record padding. What happens when one of these clients handshake with a GnuTLS server is that the client will fail to compute the correct MAC for the record. The client sends a TLS alert (bad_record_mac) and disconnects. Typically this will result in error messages such as ’A TLS fatal alert has been received’, ’Bad record MAC’, or both, on the GnuTLS server side.

GnuTLS implements a work around for this problem. However, it has to be enabled specifically. It can be enabled by using gnutls_record_disable_padding, or gnutls_priority_set with the %COMPAT priority string (see Priority Strings).

If you implement an application that have a configuration file, we recommend that you make it possible for users or administrators to specify a GnuTLS protocol priority string, which is used by your application via gnutls_priority_set. To allow the best flexibility, make it possible to have a different priority string for different incoming IP addresses.

[4] If this is not possible then please consult Interoperability.

The TLS alert protocol

The alert protocol is there to allow signals to be sent between peers. These signals are mostly used to inform the peer about the cause of a protocol failure. Some of these signals are used internally by the protocol and the application protocol does not have to cope with them (e.g. GNUTLS_A_CLOSE_NOTIFY), and others refer to the application protocol solely (e.g. GNUTLS_A_USER_CANCELLED). An alert signal includes a level indication which may be either fatal or warning. Fatal alerts always terminate the current connection, and prevent future re-negotiations using the current session ID. All alert messages are summarized in the table below.

The alert messages are protected by the record protocol, thus the information that is included does not leak. You must take extreme care for the alert information not to leak to a possible attacker, via public log files etc.

Alert

ID

Description

GNUTLS_A_CLOSE_NOTIFY

0

Close notify

GNUTLS_A_UNEXPECTED_MESSAGE

10

Unexpected message

GNUTLS_A_BAD_RECORD_MAC

20

Bad record MAC

GNUTLS_A_DECRYPTION_FAILED

21

Decryption failed

GNUTLS_A_RECORD_OVERFLOW

22

Record overflow

GNUTLS_A_DECOMPRESSION_FAILURE

30

Decompression failed

GNUTLS_A_HANDSHAKE_FAILURE

40

Handshake failed

GNUTLS_A_SSL3_NO_CERTIFICATE

41

No certificate (SSL 3.0)

GNUTLS_A_BAD_CERTIFICATE

42

Certificate is bad

GNUTLS_A_UNSUPPORTED_CERTIFICATE

43

Certificate is not supported

GNUTLS_A_CERTIFICATE_REVOKED

44

Certificate was revoked

GNUTLS_A_CERTIFICATE_EXPIRED

45

Certificate is expired

GNUTLS_A_CERTIFICATE_UNKNOWN

46

Unknown certificate

GNUTLS_A_ILLEGAL_PARAMETER

47

Illegal parameter

GNUTLS_A_UNKNOWN_CA

48

CA is unknown

GNUTLS_A_ACCESS_DENIED

49

Access was denied

GNUTLS_A_DECODE_ERROR

50

Decode error

GNUTLS_A_DECRYPT_ERROR

51

Decrypt error

GNUTLS_A_EXPORT_RESTRICTION

60

Export restriction

GNUTLS_A_PROTOCOL_VERSION

70

Error in protocol version

GNUTLS_A_INSUFFICIENT_SECURITY

71

Insufficient security

GNUTLS_A_INTERNAL_ERROR

80

Internal error

GNUTLS_A_USER_CANCELED

90

User canceled

GNUTLS_A_NO_RENEGOTIATION

100

No renegotiation is allowed

GNUTLS_A_UNSUPPORTED_EXTENSION

110

An unsupported extension was sent

GNUTLS_A_CERTIFICATE_UNOBTAINABLE

111

Could not retrieve the specified certificate

GNUTLS_A_UNRECOGNIZED_NAME

112

The server name sent was not recognized

GNUTLS_A_UNKNOWN_PSK_IDENTITY

115

The SRP/PSK username is missing or not known

The TLS handshake protocol

The handshake protocol is responsible for the ciphersuite negotiation, the initial key exchange, and the authentication of the two peers. This is fully controlled by the application layer, thus your program has to set up the required parameters. The main handshake function is gnutls_handshake. In the next paragraphs we elaborate on the handshake protocol, i.e., the ciphersuite negotiation.

TLS ciphersuites

The handshake protocol of TLS negotiates cipher suites of a special form illustrated by the TLS_DHE_RSA_WITH_3DES_CBC_SHA cipher suite name. A typical cipher suite contains these parameters:

The key exchange algorithm. DHE_RSA in the example.

The Symmetric encryption algorithm and mode 3DES_CBC in this example.

The MAC[5] algorithm used for authentication. MAC_SHA is used in the above example.

The cipher suite negotiated in the handshake protocol will affect the record protocol, by enabling encryption and data authentication. Note that you should not over rely on TLS to negotiate the strongest available cipher suite. Do not enable ciphers and algorithms that you consider weak.

All the supported ciphersuites are listed in ciphersuites.

Authentication

The key exchange algorithms of the TLS protocol offer authentication, which is a prerequisite for a secure connection. The available authentication methods in GnuTLS follow.

Certificate authentication: Authenticated key exchange using public key infrastructure and certificates (X.509 or OpenPGP).

SRP authentication: Authenticated key exchange using a password.

PSK authentication: Authenticated key exchange using a pre-shared key.

Anonymous authentication: Key exchange without peer authentication.

Client authentication

In the case of ciphersuites that use certificate authentication, the authentication of the client is optional in TLS. A server may request a certificate from the client using the gnutls_certificate_server_set_request function. We elaborate in Certificate credentials.

Resuming sessions

The TLS handshake process performs expensive calculations and a busy server might easily be put under load. To reduce the load, session resumption may be used. This is a feature of the TLS protocol which allows a client to connect to a server after a successful handshake, without the expensive calculations. This is achieved by re-using the previously established keys, meaning the server needs to store the state of established connections (unless session tickets are used – Session tickets).

Session resumption is an integral part of GnuTLS, and Session resumption and ex:resume-client illustrate typical uses of it.

[5] MAC stands for Message Authentication Code. It can be described as a keyed hash algorithm. See RFC2104.

TLS extensions

A number of extensions to the TLS protocol have been proposed mainly in [TLSEXT]. The extensions supported in GnuTLS are:

Maximum fragment length negotiation

Server name indication

Session tickets

Safe Renegotiation

and they will be discussed in the subsections that follow.

Maximum fragment length negotiation

This extension allows a TLS implementation to negotiate a smaller value for record packet maximum length. This extension may be useful to clients with constrained capabilities. The functions shown below can be used to control this extension.

gnutls_record_get_max_size

gnutls_record_set_max_size

Server name indication

A common problem in HTTPS servers is the fact that the TLS protocol is not aware of the hostname that a client connects to, when the handshake procedure begins. For that reason the TLS server has no way to know which certificate to send.

This extension solves that problem within the TLS protocol, and allows a client to send the HTTP hostname before the handshake begins within the first handshake packet. The functions gnutls_server_name_set and gnutls_server_name_get can be used to enable this extension, or to retrieve the name sent by a client.

gnutls_server_name_set

gnutls_server_name_get

Session tickets

To resume a TLS session the server normally store session parameters. This complicates deployment, and could be avoiding by delegating the storage to the client. Because session parameters are sensitive they are encrypted and authenticated with a key only known to the server and then sent to the client. The Session Tickets in RFC 5077 [TLSTKT], describe this idea, which is implemented in GnuTLS.

Safe renegotiation

TLS gives the option to two communicating parties to renegotiate and update their security parameters. One useful example of this feature was for a client to initially connect using anonymous negotiation to a server, and the renegotiate using some authenticated ciphersuite. This occurred to avoid having the client sending its credentials in the clear.

However this renegotiation, as initially designed would not ensure that the party one is renegotiating is the same as the one in the initial negotiation. For example one server could forward all renegotiation traffic to an other server who will see this traffic as an initial negotiation attempt.

This might be seen as a valid design decision, but it seems it was not widely known or understood, thus today some application protocols the TLS renegotiation feature in a manner that enables a malicious server to insert content of his choice in the beginning of a TLS session.

The most prominent vulnerability was with HTTPS. There servers request a renegotiation to enforce an anonymous user to use a certificate in order to access certain parts of a web site. The attack works by having the attacker simulate a client and connect to a server, with server-only authentication, and send some data intended to cause harm. The server will then require renegotiation from him in order to perform the request. When the proper client attempts to contact the server, the attacker hijacks that connection and forwards traffic to the initial server that requested renegotiation. The attacker will not be able to read the data exchanged between the client and the server. However, the server will (incorrectly) assume that the initial request sent by the attacker was sent by the now authenticated client. The result is a prefix plain-text injection attack.

The above is just one example. Other vulnerabilities exists that do not rely on the TLS renegotiation to change the client’s authenticated status (either TLS or application layer).

While fixing these application protocols and implementations would be one natural reaction, an extension to TLS has been designed that cryptographically binds together any renegotiated handshakes with the initial negotiation. When the extension is used, the attack is detected and the session can be terminated. The extension is specified in [RFC5746].

GnuTLS supports the safe renegotiation extension. The default behavior is as follows. Clients will attempt to negotiate the safe renegotiation extension when talking to servers. Servers will accept the extension when presented by clients. Clients and servers will permit an initial handshake to complete even when the other side does not support the safe renegotiation extension. Clients and servers will refuse renegotiation attempts when the extension has not been negotiated.

Note that permitting clients to connect to servers when the safe renegotiation extension is not enabled, is open up for attacks. Changing this default behavior would prevent interoperability against the majority of deployed servers out there. We will reconsider this default behavior in the future when more servers have been upgraded. Note that it is easy to configure clients to always require the safe renegotiation extension from servers.

To modify the default behavior, we have introduced some new priority strings (see Priority Strings). The %UNSAFE_RENEGOTIATION priority string permits (re-)handshakes even when the safe renegotiation extension was not negotiated. The default behavior is %PARTIAL_RENEGOTIATION that will prevent renegotiation with clients and servers not supporting the extension. This is secure for servers but leaves clients vulnerable to some attacks, but this is a trade-off between security and compatibility with old servers. The %SAFE_RENEGOTIATION priority string makes clients and servers require the extension for every handshake. The latter is the most secure option for clients, at the cost of not being able to connect to legacy servers. Servers will also deny clients that do not support the extension from connecting.

It is possible to disable use of the extension completely, in both clients and servers, by using the %DISABLE_SAFE_RENEGOTIATION priority string however we strongly recommend you to only do this for debugging and test purposes.

The default values if the flags above are not specified are:

Server:

%PARTIAL_RENEGOTIATION

Client:

%PARTIAL_RENEGOTIATION

For applications we have introduced a new API related to safe renegotiation. The gnutls_safe_renegotiation_status function is used to check if the extension has been negotiated on a session, and can be used both by clients and servers.

How to use TLS in application protocols

This chapter is intended to provide some hints on how to use the TLS over simple custom made application protocols. The discussion below mainly refers to the TCP/IP transport layer but may be extended to other ones too.

Separate ports

Traditionally SSL was used in application protocols by assigning a new port number for the secure services. That way two separate ports were assigned, one for the non secure sessions, and one for the secured ones. This has the benefit that if a user requests a secure session then the client will try to connect to the secure port and fail otherwise. The only possible attack with this method is a denial of service one. The most famous example of this method is the famous “HTTP over TLS” or HTTPS protocol [RFC2818].

Despite its wide use, this method is not as good as it seems. This approach starts the TLS Handshake procedure just after the client connects on the —so called— secure port. That way the TLS protocol does not know anything about the client, and popular methods like the host advertising in HTTP do not work[6]. There is no way for the client to say “I connected to YYY server” before the Handshake starts, so the server cannot possibly know which certificate to use.

Other than that it requires two separate ports to run a single service, which is unnecessary complication. Due to the fact that there is a limitation on the available privileged ports, this approach was soon obsoleted.

Upward negotiation

Other application protocols[7] use a different approach to enable the secure layer. They use something often called as the “TLS upgrade” method. This method is quite tricky but it is more flexible. The idea is to extend the application protocol to have a “STARTTLS” request, whose purpose it to start the TLS protocols just after the client requests it. This approach does not require any extra port to be reserved. There is even an extension to HTTP protocol to support that method [RFC2817].

The tricky part, in this method, is that the “STARTTLS” request is sent in the clear, thus is vulnerable to modifications. A typical attack is to modify the messages in a way that the client is fooled and thinks that the server does not have the “STARTTLS” capability. See a typical conversation of a hypothetical protocol:

(client connects to the server)

CLIENT: HELLO I’M MR. XXX

SERVER: NICE TO MEET YOU XXX

CLIENT: PLEASE START TLS

SERVER: OK

*** TLS STARTS

CLIENT: HERE ARE SOME CONFIDENTIAL DATA

And see an example of a conversation where someone is acting in between:

(client connects to the server)

CLIENT: HELLO I’M MR. XXX

SERVER: NICE TO MEET YOU XXX

CLIENT: PLEASE START TLS

(here someone inserts this message)

SERVER: SORRY I DON’T HAVE THIS CAPABILITY

CLIENT: HERE ARE SOME CONFIDENTIAL DATA

As you can see above the client was fooled, and was dummy enough to send the confidential data in the clear.

How to avoid the above attack? As you may have already noticed this one is easy to avoid. The client has to ask the user before it connects whether the user requests TLS or not. If the user answered that he certainly wants the secure layer the last conversation should be:

(client connects to the server)

CLIENT: HELLO I’M MR. XXX

SERVER: NICE TO MEET YOU XXX

CLIENT: PLEASE START TLS

(here someone inserts this message)

SERVER: SORRY I DON’T HAVE THIS CAPABILITY

CLIENT: BYE

(the client notifies the user that the secure connection was not possible)

This method, if implemented properly, is far better than the traditional method, and the security properties remain the same, since only denial of service is possible. The benefit is that the server may request additional data before the TLS Handshake protocol starts, in order to send the correct certificate, use the correct password file, or anything else!

[6] See also the Server Name Indication extension on serverind.

[7] See LDAP, IMAP etc.

On SSL 2 and older protocols

One of the initial decisions in the GnuTLS development was to implement the known security protocols for the transport layer. Initially TLS 1.0 was implemented since it was the latest at that time, and was considered to be the most advanced in security properties. Later the SSL 3.0 protocol was implemented since it is still the only protocol supported by several servers and there are no serious security vulnerabilities known.

One question that may arise is why we didn’t implement SSL 2.0 in the library. There are several reasons, most important being that it has serious security flaws, unacceptable for a modern security library. Other than that, this protocol is barely used by anyone these days since it has been deprecated since 1996. The security problems in SSL 2.0 include:

Message integrity compromised. The SSLv2 message authentication uses the MD5 function, and is insecure.

Man-in-the-middle attack. There is no protection of the handshake in SSLv2, which permits a man-in-the-middle attack.

Truncation attack. SSLv2 relies on TCP FIN to close the session, so the attacker can forge a TCP FIN, and the peer cannot tell if it was a legitimate end of data or not.

Weak message integrity for export ciphers. The cryptographic keys in SSLv2 are used for both message authentication and encryption, so if weak encryption schemes are negotiated (say 40-bit keys) the message authentication code use the same weak key, which isn’t necessary.

Other protocols such as Microsoft’s PCT 1 and PCT 2 were not implemented because they were also abandoned and deprecated by SSL 3.0 and later TLS 1.0.

Chapter 4. Certificate authentication

The most known authentication method of TLS are certificates. The PKIX [PKIX] public key infrastructure is daily used by anyone using a browser today. GnuTLS supports both X.509 certificates [PKIX] and OpenPGP certificates using a common API.

The key exchange algorithms supported by certificate authentication are shown in tab:key-exchange.

Key exchange

Description

RSA

The RSA algorithm is used to encrypt a key and send it to the peer. The certificate must allow the key to be used for encryption.

RSA_EXPORT

The RSA algorithm is used to encrypt a key and send it to the peer. In the EXPORT algorithm, the server signs temporary RSA parameters of 512 bits — which are considered weak — and sends them to the client.

DHE_RSA

The RSA algorithm is used to sign ephemeral Diffie-Hellman parameters which are sent to the peer. The key in the certificate must allow the key to be used for signing. Note that key exchange algorithms which use ephemeral Diffie-Hellman parameters, offer perfect forward secrecy. That means that even if the private key used for signing is compromised, it cannot be used to reveal past session data.

ECDHE_RSA

The RSA algorithm is used to sign ephemeral elliptic curve Diffie-Hellman parameters which are sent to the peer. The key in the certificate must allow the key to be used for signing. It also offers perfect forward secrecy. That means that even if the private key used for signing is compromised, it cannot be used to reveal past session data.

DHE_DSS

The DSA algorithm is used to sign ephemeral Diffie-Hellman parameters which are sent to the peer. The certificate must contain DSA parameters to use this key exchange algorithm. DSA is the algorithm of the Digital Signature Standard (DSS).

ECDHE_ECDSA

The Elliptic curve DSA algorithm is used to sign ephemeral elliptic curve Diffie-Hellman parameters which are sent to the peer. The certificate must contain ECDSA parameters to use this key exchange algorithm.

X.509 certificates

The X.509 protocols rely on a hierarchical trust model. In this trust model Certification Authorities (CAs) are used to certify entities. Usually more than one certification authorities exist, and certification authorities may certify other authorities to issue certificates as well, following a hierarchical model.

One needs to trust one or more CAs for his secure communications. In that case only the certificates issued by the trusted authorities are acceptable. The framework is illustrated on fig:x509.

X.509 certificate structure

An X.509 certificate usually contains information about the certificate holder, the signer, a unique serial number, expiration dates and some other fields [PKIX] as shown in tab:x509.

Field

Description

version

The field that indicates the version of the certificate.

serialNumber

This field holds a unique serial number per certificate.

signature

The issuing authority’s signature.

issuer

Holds the issuer’s distinguished name.

validity

The activation and expiration dates.

subject

The subject’s distinguished name of the certificate.

extensions

The extensions are fields only present in version 3 certificates.

The certificate’s subject or issuer name is not just a single string. It is a Distinguished name and in the ASN.1 notation is a sequence of several object identifiers with their corresponding values. Some of available OIDs to be used in an X.509 distinguished name are defined in gnutls/x509.h.

The Version field in a certificate has values either 1 or 3 for version 3 certificates. Version 1 certificates do not support the extensions field so it is not possible to distinguish a CA from a person, thus their usage should be avoided.

The validity dates are there to indicate the date that the specific certificate was activated and the date the certificate’s key would be considered invalid.

Certificate extensions are there to include information about the certificate’s subject that did not fit in the typical certificate fields. Those may be e-mail addresses, flags that indicate whether the belongs to a CA etc. All the supported X.509 version 3 extensions are shown in tab:x509-ext.

Extension

OID

Description

Subject key id

2.5.29.14

An identifier of the key of the subject.

Authority key id

2.5.29.35

An identifier of the authority’s key used to sign the certificate.

Subject alternative name

2.5.29.17

Alternative names to subject’s distinguished name.

Key usage

2.5.29.15

Constraints the key’s usage of the certificate.

Extended key usage

2.5.29.37

Constraints the purpose of the certificate.

Basic constraints

2.5.29.19

Indicates whether this is a CA certificate or not, and specify the maximum path lengths of certificate chains.

CRL distribution points

2.5.29.31

This extension is set by the CA, in order to inform about the issued CRLs.

Proxy Certification Information

1.3.6.1.5.5.7.1.14

Proxy Certificates includes this extension that contains the OID of the proxy policy language used, and can specify limits on the maximum lengths of proxy chains. Proxy Certificates are specified in [RFC3820].

In GnuTLS the X.509 certificate structures are handled using the gnutls_x509_crt_t type and the corresponding private keys with the gnutls_x509_privkey_t type. All the available functions for X.509 certificate handling have their prototypes in gnutls/x509.h. An example program to demonstrate the X.509 parsing capabilities can be found at ex:x509-info.

X.509 distinguished names

The “subject” of an X.509 certificate is not described by a single name, but rather with a distinguished name. This in X.509 terminology is a list of strings each associated an object identifier. To make things simple GnuTLS provides gnutls_x509_crt_get_dn which follows the rules in [RFC4514] and returns a single string. Access to each string by individual object identifiers can be accessed using gnutls_x509_crt_get_dn_by_oid.

gnutls_x509_crt_get_dn

gnutls_x509_crt_get_dn_by_oid

gnutls_x509_crt_get_dn_oid

The more powerful gnutls_x509_crt_get_subject and gnutls_x509_dn_get_rdn_ava provide efficient access to the contents of the distinguished name structure.

gnutls_x509_crt_get_subject

gnutls_x509_dn_get_rdn_ava

Similar functions exist to access the distinguished name of the issuer of the certificate.

gnutls_x509_crt_get_issuer_dn

gnutls_x509_crt_get_issuer_dn_by_oid

gnutls_x509_crt_get_issuer_dn_oid

gnutls_x509_crt_get_issuer

Verifying X.509 certificate paths

Verifying certificate paths is important in X.509 authentication. For this purpose the following functions are provided.

gnutls_x509_trust_list_add_cas

gnutls_x509_trust_list_add_named_crt

gnutls_x509_trust_list_add_crls

gnutls_x509_trust_list_verify_crt

gnutls_x509_trust_list_verify_named_crt

The verification function will verify a given certificate chain against a list of certificate authorities and certificate revocation lists, and output a bit-wise OR of elements of the gnutls_certificate_status_t enumeration shown in gnutls_certificate_status_t.

GNUTLS_CERT_INVALID

The certificate is not signed by one of the known authorities or the signature is invalid.

GNUTLS_CERT_REVOKED

Certificate is revoked by its authority. In X.509 this will be set only if CRLs are checked.

GNUTLS_CERT_SIGNER_NOT_FOUND

The certificate’s issuer is not known. This is the case if the issue is not included in the trusted certificate list. not found.

GNUTLS_CERT_SIGNER_NOT_CA

The certificateâs signer was not a CA. This may happen if this was a version 1 certificate, which is common with some CAs, or a version 3 certificate without the basic constrains extension.

GNUTLS_CERT_INSECURE_ALGORITHM

The certificate was signed using an insecure algorithm such as MD2 or MD5. These algorithms have been broken and should not be trusted.

GNUTLS_CERT_NOT_ACTIVATED

The certificate is not yet activated.

GNUTLS_CERT_EXPIRED

The certificate has expired.

An example of certificate verification is shown in ex:verify2. It is also possible to have a set of certificates that are trusted for a particular server but not to authorize other certificates. This purpose is served by the functions gnutls_x509_trust_list_add_named_crt and gnutls_x509_trust_list_verify_named_crt.

Verifying a certificate in the context of TLS session

When operating in the context of a TLS session, if the trusted certificate authority list has been set via the gnutls_certificate_set_x509_trust_file and gnutls_certificate_set_x509_crl_file, it is not required to setup a trusted list as above. The function gnutls_certificate_verify_peers2 may then be used to verify the peer’s certificate chain.

There is also the possibility to pass some input to the verification functions in the form of flags. For gnutls_x509_trust_list_verify_crt the flags are passed straightforward, but gnutls_certificate_verify_peers2 depends on the flags set by calling gnutls_certificate_set_verify_flags. All the available flags are part of the enumeration gnutls_certificate_verify_flags shown in gnutls_certificate_verify_flags.

GNUTLS_VERIFY_DISABLE_CA_SIGN

If set a signer does not have to be a certificate authority. This flag should normaly be disabled, unless you know what this means.

GNUTLS_VERIFY_ALLOW_X509_V1_CA_CRT

Allow trusted CA certiï¬cates with version 1. This is safer than GNUTLS_VERIFY_ALLOW_ANY_X509_V1_CA_CRT , and should be used instead. That way only signers in your trusted list will be allowed to have certiï¬cates of version 1. This is the default.

GNUTLS_VERIFY_DO_NOT_ALLOW_SAME

If a certificate is not signed by anyone trusted but exists in the trusted CA list do not treat it as trusted.

GNUTLS_VERIFY_ALLOW_ANY_X509_V1_CA_CRT

Allow CA certificates that have version 1 (both root and intermediate). This might be dangerous since those haven’t the basicConstraints extension. Must be used in combination with GNUTLS_VERIFY_ALLOW_X509_V1_CA_CRT .

GNUTLS_VERIFY_ALLOW_SIGN_RSA_MD2

Allow certificates to be signed using the broken MD2 algorithm.

GNUTLS_VERIFY_ALLOW_SIGN_RSA_MD5

Allow certificates to be signed using the broken MD5 algorithm.

GNUTLS_VERIFY_DISABLE_TIME_CHECKS

Disable checking of activation and expiration validity periods of certificate chains. Don’t set this unless you understand the security implications.

GNUTLS_VERIFY_DISABLE_TRUSTED_TIME_CHECKS

If set a signer in the trusted list is never checked for expiration or activation.

GNUTLS_VERIFY_DO_NOT_ALLOW_X509_V1_CA_CRT

Do not allow trusted CA certificates that have version 1. This option is to be used to deprecate all certificates of version 1.

GNUTLS_VERIFY_DISABLE_CRL_CHECKS

Disable checking for validity using certificate revocation lists.

Although the verification of a certificate path indicates that the certificate is signed by trusted authority, does not reveal anything about the peer’s identity. It is required to verify if the certificate’s owner is the one you expect. For more information consult [RFC2818] and section ex:verify for an example.

Verifying a certificate using trust on first use authentication

It is possible to use a trust on first use (similar to SSH) authentication method in GnuTLS. That is the concept used by the SSH programs, where the public key of the peer is not verified, or verified in an out-of-bound way, but subsequent connections to the same peer require the public key to remain the same. Such a system in combination with the typical CA verification of a certificate, and OCSP revocation checks, can help to provide multiple factor verification, where a single point of failure is not enough to compromise the system. For example a server compromise may be detected using OCSP, and a CA compromise can be detected using the trust on first use method. Such a hybrid system with X.509 and trust on first use authentication is shown in Simple client example with SSH-style certificate verification.

gnutls_verify_stored_pubkey

gnutls_store_pubkey

In addition to the above the gnutls_store_commitment can be used to implement a key-pinning architecture as in [KEYPIN]. This provides a way for web server to commit on a public key that is not yet active.

gnutls_store_commitment

The storage and verification functions may be used with the default text file based back-end, or another back-end may be specified. That should contain storage and retrieval functions and specified as below.

gnutls_tdb_init

gnutls_tdb_deinit

gnutls_tdb_set_verify_func

gnutls_tdb_set_store_func

gnutls_tdb_set_store_commitment_func

OpenPGP certificates

The OpenPGP key authentication relies on a distributed trust model, called the “web of trust”. The “web of trust” uses a decentralized system of trusted introducers, which are the same as a CA. OpenPGP allows anyone to sign anyone else’s public key. When Alice signs Bob’s key, she is introducing Bob’s key to anyone who trusts Alice. If someone trusts Alice to introduce keys, then Alice is a trusted introducer in the mind of that observer. For example in fig:openpgp, David trusts Alice to be an introducer and Alice signed Bob’s key thus Dave trusts Bob’s key to be the real one.

There are some key points that are important in that model. In the example Alice has to sign Bob’s key, only if she is sure that the key belongs to Bob. Otherwise she may also make Dave falsely believe that this is Bob’s key. Dave has also the responsibility to know who to trust. This model is similar to real life relations.

Just see how Charlie behaves in the previous example. Although he has signed Bob’s key - because he knows, somehow, that it belongs to Bob - he does not trust Bob to be an introducer. Charlie decided to trust only Kevin, for some reason. A reason could be that Bob is lazy enough, and signs other people’s keys without being sure that they belong to the actual owner.

OpenPGP certificate structure

In GnuTLS the OpenPGP key structures [RFC2440] are handled using the gnutls_openpgp_crt_t type and the corresponding private keys with the gnutls_openpgp_privkey_t type. All the prototypes for the key handling functions can be found at gnutls/openpgp.h.

Verifying an OpenPGP certificate

The verification functions of OpenPGP keys, included in GnuTLS, are simple ones, and do not use the features of the “web of trust”. For that reason, if the verification needs are complex, the assistance of external tools like GnuPG and GPGME[8] is recommended.

In GnuTLS there is a verification function for OpenPGP certificates, the gnutls_openpgp_crt_verify_ring. This checks an OpenPGP key against a given set of public keys (keyring) and returns the key status. The key verification status is the same as in X.509 certificates, although the meaning and interpretation are different. For example an OpenPGP key may be valid, if the self signature is ok, even if no signers were found. The meaning of verification status flags is the same as in the X.509 certificates (see gnutls_certificate_verify_flags).

gnutls_openpgp_crt_verify_ring

gnutls_openpgp_crt_verify_self

Verifying a certificate in the context of a TLS session

Similarly with X.509 certificates, one needs to specify the OpenPGP keyring file in the credentials structure. The certificates in this file will be used by gnutls_certificate_verify_peers2 to verify the signatures in the certificate sent by the peer.

gnutls_certificate_set_openpgp_keyring_file

[8] http://www.gnupg.org/related_software/gpgme/

Digital signatures

In this section we will provide some information about digital signatures, how they work, and give the rationale for disabling some of the algorithms used.

Digital signatures work by using somebody’s secret key to sign some arbitrary data. Then anybody else could use the public key of that person to verify the signature. Since the data may be arbitrary it is not suitable input to a cryptographic digital signature algorithm. For this reason and also for performance cryptographic hash algorithms are used to preprocess the input to the signature algorithm. This works as long as it is difficult enough to generate two different messages with the same hash algorithm output. In that case the same signature could be used as a proof for both messages. Nobody wants to sign an innocent message of donating 1 € to Greenpeace and find out that he donated 1.000.000 € to Bad Inc.

For a hash algorithm to be called cryptographic the following three requirements must hold:

Preimage resistance. That means the algorithm must be one way and given the output of the hash function H(x), it is impossible to calculate x.

2nd preimage resistance. That means that given a pair x,y with y=H(x) it is impossible to calculate an x' such that y=H(x').

Collision resistance. That means that it is impossible to calculate random x and x' such H(x')=H(x).

The last two requirements in the list are the most important in digital signatures. These protect against somebody who would like to generate two messages with the same hash output. When an algorithm is considered broken usually it means that the Collision resistance of the algorithm is less than brute force. Using the birthday paradox the brute force attack takes 2^{((hash size) / 2)} operations. Today colliding certificates using the MD5 hash algorithm have been generated as shown in [WEGER].

There has been cryptographic results for the SHA-1 hash algorithms as well, although they are not yet critical. Before 2004, MD5 had a presumed collision strength of 2^{64}, but it has been showed to have a collision strength well under 2^{50}. As of November 2005, it is believed that SHA-1’s collision strength is around 2^{63}. We consider this sufficiently hard so that we still support SHA-1. We anticipate that SHA-256/386/512 will be used in publicly-distributed certificates in the future. When 2^{63} can be considered too weak compared to the computer power available sometime in the future, SHA-1 will be disabled as well. The collision attacks on SHA-1 may also get better, given the new interest in tools for creating them.

Trading security for interoperability

If you connect to a server and use GnuTLS’ functions to verify the certificate chain, and get a GNUTLS_CERT_INSECURE_ALGORITHM validation error (see Verifying X.509 certificate paths), it means that somewhere in the certificate chain there is a certificate signed using RSA-MD2 or RSA-MD5. These two digital signature algorithms are considered broken, so GnuTLS fails verifying the certificate. In some situations, it may be useful to be able to verify the certificate chain anyway, assuming an attacker did not utilize the fact that these signatures algorithms are broken. This section will give help on how to achieve that.

It is important to know that you do not have to enable any of the flags discussed here to be able to use trusted root CA certificates self-signed using RSA-MD2 or RSA-MD5. The certificates in the trusted list are considered trusted irrespective of the signature.

If you are using gnutls_certificate_verify_peers2 to verify the certificate chain, you can call gnutls_certificate_set_verify_flags with the flags:

GNUTLS_VERIFY_ALLOW_SIGN_RSA_MD2

GNUTLS_VERIFY_ALLOW_SIGN_RSA_MD5

as in the following example:

  gnutls_certificate_set_verify_flags (x509cred,
                                       GNUTLS_VERIFY_ALLOW_SIGN_RSA_MD5);

This will tell the verifier algorithm to enable RSA-MD5 when verifying the certificates.

If you are using gnutls_x509_crt_verify or gnutls_x509_crt_list_verify, you can pass the GNUTLS_VERIFY_ALLOW_SIGN_RSA_MD5 parameter directly in the flags parameter.

If you are using these flags, it may also be a good idea to warn the user when verification failure occur for this reason. The simplest is to not use the flags by default, and only fall back to using them after warning the user. If you wish to inspect the certificate chain yourself, you can use gnutls_certificate_get_peers to extract the raw server’s certificate chain, gnutls_x509_crt_list_import to parse each of the certificates, and then gnutls_x509_crt_get_signature_algorithm to find out the signing algorithm used for each certificate. If any of the intermediary certificates are using GNUTLS_SIGN_RSA_MD2 or GNUTLS_SIGN_RSA_MD5, you could present a warning.

Chapter 5. Shared-key and anonymous authentication

In addition to certificate authentication, the TLS protocol may be used with password, shared-key and anonymous authentication methods. The rest of this chapter discusses details of these methods.

SRP authentication

Authentication using SRP

GnuTLS supports authentication via the Secure Remote Password or SRP protocol (see [RFC2945,TOMSRP] for a description). The SRP key exchange is an extension to the TLS protocol, and it provides an authenticated with a password key exchange. The peers can be identified using a single password, or there can be combinations where the client is authenticated using SRP and the server using a certificate.

The advantage of SRP authentication, over other proposed secure password authentication schemes, is that SRP is not susceptible to off-line dictionary attacks. Moreover, SRP does not require the server to hold the user’s password. This kind of protection is similar to the one used traditionally in the UNIX /etc/passwd file, where the contents of this file did not cause harm to the system security if they were revealed. The SRP needs instead of the plain password something called a verifier, which is calculated using the user’s password, and if stolen cannot be used to impersonate the user.

Typical conventions in SRP are a password file, called tpasswd that holds the SRP verifiers (encoded passwords) and another file, tpasswd.conf, which holds the allowed SRP parameters. The included in GnuTLS helper follow those conventions. The srptool program, discussed in the next section is a tool to manipulate the SRP parameters.

The implementation in GnuTLS is based on [TLSSRP]. The supported key exchange methods are shown below.

SRP:

Authentication using the SRP protocol.

SRP_DSS:

Client authentication using the SRP protocol. Server is authenticated using a certificate with DSA parameters.

SRP_RSA:

Client authentication using the SRP protocol. Server is authenticated using a certificate with RSA parameters.

gnutls_srp_verifier

gnutls_srp_base64_encode

gnutls_srp_base64_decode

Invoking srptool

Simple program that emulates the programs in the Stanford SRP (Secure Remote Password) libraries using GnuTLS. It is intended for use in places where you don’t expect SRP authentication to be the used for system users.

In brief, to use SRP you need to create two files. These are the password file that holds the users and the verifiers associated with them and the configuration file to hold the group parameters (called tpasswd.conf).

This section was generated by AutoGen, using the agtexi-cmd template and the option descriptions for the srptool program. This software is released under the GNU General Public License, version 3 or later.

srptool usage (-h)

This is the automatically generated usage text for srptool:

srptool - GnuTLS SRP tool - Ver. @VERSION@
USAGE:  srptool [ -<flag> [<val>] | --<name>[{=| }<val>] ]...

   -d, --debug=num            Enable debugging.
                                - It must be in the range:
                                  0 to 9999
   -i, --index                specify the index of the group parameters in tpasswd.conf to use.
   -u, --username=str         specify a username
   -p, --passwd=str           specify a password file.
   -s, --salt=num             specify salt size.
       --verify               just verify the password.
   -v, --passwd-conf=str      specify a password conf file.
       --create-conf=str      Generate a password configuration file.
   -v, --version[=arg]        Output version information and exit
   -h, --help                 Display extended usage information and exit
   -!, --more-help            Extended usage information passed thru pager

Options are specified by doubled hyphens and their name or by a single
hyphen and the flag character.

Simple program that emulates the programs in the Stanford SRP (Secure
Remote Password) libraries using GnuTLS.  It is intended for use in
places where you don't expect SRP authentication to be the used for
system users.

In  brief,  to use SRP you need to create two files. These are the
password file that holds the users and the verifiers associated with
them  and  the configuration file to hold the group parameters (called
tpasswd.conf).

please send bug reports to:  bug-gnutls@gnu.org

create-conf option

This is the “generate a password configuration file.” option. This generates a password configuration file (tpasswd.conf) containing the required for TLS parameters.

debug option (-d)

This is the “enable debugging.” option. Specifies the debug level.

index option (-i)

This is the “specify the index of the group parameters in tpasswd.conf to use.” option.

passwd option (-p)

This is the “specify a password file.” option.

passwd-conf option (-v)

This is the “specify a password conf file.” option. Specify a filename or a PKCS #11 URL to read the CAs from.

salt option (-s)

This is the “specify salt size.” option.

username option (-u)

This is the “specify a username” option.

verify option

This is the “just verify the password.” option. Verifies the password provided against the password file.

srptool exit status

One of the following exit values will be returned:

‘0’

Successful program execution.

‘1’

The operation failed or the command syntax was not valid.

srptool See Also

gnutls-cli-debug (1), gnutls-serv (1), srptool (1), psktool (1), certtool (1)

srptool Examples

To create tpasswd.conf which holds the g and n values for SRP protocol (generator and a large prime), run:

$ srptool --create-conf /etc/tpasswd.conf

This command will create /etc/tpasswd and will add user ’test’ (you will also be prompted for a password). Verifiers are stored by default in the way libsrp expects.

$ srptool --passwd /etc/tpasswd --passwd-conf /etc/tpasswd.conf -u test

This command will check against a password. If the password matches the one in /etc/tpasswd you will get an ok.

$ srptool --passwd /etc/tpasswd --passwd\-conf /etc/tpasswd.conf --verify -u test

PSK authentication

Authentication using PSK

Authentication using Pre-shared keys is a method to authenticate using usernames and binary keys. This protocol avoids making use of public key infrastructure and expensive calculations, thus it is suitable for constraint clients.

The implementation in GnuTLS is based on [TLSPSK]. The supported PSK key exchange methods are:

PSK:

Authentication using the PSK protocol.

DHE-PSK:

Authentication using the PSK protocol and Diffie-Hellman key exchange. This method offers perfect forward secrecy.

ECDHE-PSK:

Authentication using the PSK protocol and Elliptic curve Diffie-Hellman key exchange. This method offers perfect forward secrecy.

Helper functions to generate and maintain PSK keys are also included in GnuTLS.

gnutls_key_generate

gnutls_hex_encode

gnutls_hex_decode

Invoking psktool

Program that generates random keys for use with TLS-PSK. The keys are stored in hexadecimal format in a key file.

This section was generated by AutoGen, using the agtexi-cmd template and the option descriptions for the psktool program. This software is released under the GNU General Public License, version 3 or later.

psktool usage (-h)

This is the automatically generated usage text for psktool:

psktool - GnuTLS PSK tool - Ver. @VERSION@
USAGE:  psktool [ -<flag> [<val>] | --<name>[{=| }<val>] ]...

   -d, --debug=num            Enable debugging.
                                - It must be in the range:
                                  0 to 9999
   -s, --keysize=num          specify the key size in bytes
                                - It must be in the range:
                                  0 to 512
   -u, --username=str         specify a username
   -p, --passwd=str           specify a password file.
   -v, --version[=arg]        Output version information and exit
   -h, --help                 Display extended usage information and exit
   -!, --more-help            Extended usage information passed thru pager

Options are specified by doubled hyphens and their name or by a single
hyphen and the flag character.

Program  that generates random keys for use with TLS-PSK. The keys are
stored in hexadecimal format in a key file.

please send bug reports to:  bug-gnutls@gnu.org

debug option (-d)

This is the “enable debugging.” option. Specifies the debug level.

keysize option (-s)

This is the “specify the key size in bytes” option.

passwd option (-p)

This is the “specify a password file.” option.

username option (-u)

This is the “specify a username” option.

psktool exit status

One of the following exit values will be returned:

‘0’

Successful program execution.

‘1’

The operation failed or the command syntax was not valid.

psktool See Also

gnutls-cli-debug (1), gnutls-serv (1), srptool (1), certtool (1)

psktool Examples

To add a user ’psk_identity’ in passwd.psk for use with GnuTLS run:

$ ./psktool -u psk_identity -p passwd.psk
Generating a random key for user 'psk_identity'
Key stored to passwd.psk
$ cat psks.txt
psk_identity:88f3824b3e5659f52d00e959bacab954b6540344
$

This command will create passwd.psk if it does not exist and will add user ’psk_identity’ (you will also be prompted for a password).

Anonymous authentication

The anonymous key exchange offers encryption without any indication of the peer’s identity. This kind of authentication is vulnerable to a man in the middle attack, but can be used even if there is no prior communication or shared trusted parties with the peer. Moreover it is useful when complete anonymity is required. Unless in one of the above cases, do not use anonymous authentication.

The available key exchange algorithms for anonymous authentication are shown below.

ANON_DH:

This algorithm exchanges Diffie-Hellman parameters.

ANON_ECDH:

This algorithm exchanges elliptic curve Diffie-Hellman parameters. It is more efficient than ANON_DH on equivalent security levels.

Chapter 6. More on certificate authentication

Certificates are not the only structures involved in a public key infrastructure. Several other structures that are used for certificate requests, encrypted private keys, revocation lists, GnuTLS abstract key structures, etc., are discussed in this chapter.

PKCS #10 certificate requests

A certificate request is a structure, which contain information about an applicant of a certificate service. It usually contains a private key, a distinguished name and secondary data such as a challenge password. GnuTLS supports the requests defined in PKCS #10 [RFC2986]. Other formats of certificate requests are not currently supported.

A certificate request can be generated by associating it with a private key, setting the subject’s information and finally self signing it. The last step ensures that the requester is in possession of the private key.

gnutls_x509_crq_set_version

gnutls_x509_crq_set_dn_by_oid

gnutls_x509_crq_set_key_usage

gnutls_x509_crq_set_key_purpose_oid

gnutls_x509_crq_set_basic_constraints

The gnutls_x509_crq_set_key and gnutls_x509_crq_sign2 functions associate the request with a private key and sign it. If a request is to be signed with a key residing in a PKCS #11 token it is recommended to use the signing functions shown in Abstract key types.

gnutls_x509_crq_set_key

gnutls_x509_crq_sign2

The following example is about generating a certificate request, and a private key. A certificate request can be later be processed by a CA which should return a signed certificate.

/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <gnutls/gnutls.h>
#include <gnutls/x509.h>
#include <gnutls/abstract.h>
#include <time.h>

/* This example will generate a private key and a certificate
 * request.
 */

int
main (void)
{
  gnutls_x509_crq_t crq;
  gnutls_x509_privkey_t key;
  unsigned char buffer[10 * 1024];
  size_t buffer_size = sizeof (buffer);
  unsigned int bits;

  gnutls_global_init ();

  /* Initialize an empty certificate request, and
   * an empty private key.
   */
  gnutls_x509_crq_init (&crq);

  gnutls_x509_privkey_init (&key);

  /* Generate an RSA key of moderate security.
   */
  bits = gnutls_sec_param_to_pk_bits (GNUTLS_PK_RSA, GNUTLS_SEC_PARAM_NORMAL);
  gnutls_x509_privkey_generate (key, GNUTLS_PK_RSA, bits, 0);

  /* Add stuff to the distinguished name
   */
  gnutls_x509_crq_set_dn_by_oid (crq, GNUTLS_OID_X520_COUNTRY_NAME,
                                 0, "GR", 2);

  gnutls_x509_crq_set_dn_by_oid (crq, GNUTLS_OID_X520_COMMON_NAME,
                                 0, "Nikos", strlen ("Nikos"));

  /* Set the request version.
   */
  gnutls_x509_crq_set_version (crq, 1);

  /* Set a challenge password.
   */
  gnutls_x509_crq_set_challenge_password (crq, "something to remember here");

  /* Associate the request with the private key
   */
  gnutls_x509_crq_set_key (crq, key);

  /* Self sign the certificate request.
   */
  gnutls_x509_crq_sign2 (crq, key, GNUTLS_DIG_SHA1, 0);

  /* Export the PEM encoded certificate request, and
   * display it.
   */
  gnutls_x509_crq_export (crq, GNUTLS_X509_FMT_PEM, buffer, &buffer_size);

  printf ("Certificate Request: \n%s", buffer);

  /* Export the PEM encoded private key, and
   * display it.
   */
  buffer_size = sizeof (buffer);
  gnutls_x509_privkey_export (key, GNUTLS_X509_FMT_PEM, buffer, &buffer_size);

  printf ("\n\nPrivate key: \n%s", buffer);

  gnutls_x509_crq_deinit (crq);
  gnutls_x509_privkey_deinit (key);

  return 0;

}

PKIX certificate revocation lists

A certificate revocation list (CRL) is a structure issued by an authority periodically containing a list of revoked certificates serial numbers. The CRL structure is signed with the issuing authorities’ keys. A typical CRL contains the fields as shown in tab:crl. Certificate revocation lists are used to complement the expiration date of a certificate, in order to account for other reasons of revocation, such as compromised keys, etc.

A certificate request can be generated by associating it with a private key, setting the subject’s information and finally self signing it. The last step ensures that the requester is in possession of the private key. Each CRL is valid for limited amount of time and is required to provide, except for the current issuing time, also the issuing time of the next update.

Field

Description

version

The field that indicates the version of the CRL structure.

signature

A signature by the issuing authority.

issuer

Holds the issuer’s distinguished name.

thisUpdate

The issuing time of the revocation list.

nextUpdate

The issuing time of the revocation list that will update that one.

revokedCertificates

List of revoked certificates serial numbers.

extensions

Optional CRL structure extensions.

gnutls_x509_crl_set_version

gnutls_x509_crl_set_crt_serial

gnutls_x509_crl_set_crt

gnutls_x509_crl_set_next_update

gnutls_x509_crl_set_this_update

The gnutls_x509_crl_sign2 and gnutls_x509_crl_privkey_sign functions sign the revocation list with a private key. The latter function can be used to sign with a key residing in a PKCS #11 token.

gnutls_x509_crl_sign2

gnutls_x509_crl_privkey_sign

Few extensions on the CRL structure are supported, including the CRL number extension and the authority key identifier.

gnutls_x509_crl_set_number

gnutls_x509_crl_set_authority_key_id

OCSP certificate status checking

Certificates may be revoked before their expiration time has been reached. There are several reasons for revoking certificates, but a typical situation is when the private key associated with a certificate has been compromised. Traditionally, Certificate Revocation Lists (CRLs) have been used by application to implement revocation checking, however, several problems with CRLs have been identified [RIVESTCRL].

The Online Certificate Status Protocol, or OCSP [RFC2560], is a widely implemented protocol to perform certificate revocation status checking. An application that wish to verify the identity of a peer will verify the certificate against a set of trusted certificates and then check whether the certificate is listed in a CRL and/or perform an OCSP check for the certificate.

Before performing the OCSP query, the application will need to figure out the address of the OCSP server. The OCSP server address can be provided by the local user in manual configuration or may be stored in the certificate that is being checked. The latter is due to an extension field called the Authority Information Access (AIA) which may hold the location of the OCSP responder in the access method called id-ad-ocsp. The following function extracts this information from a certificate.

gnutls_x509_crt_get_authority_info_access

There are several functions in GnuTLS for creating and manipulating OCSP requests and responses. The general idea is that a client application create an OCSP request object, store some information about the certificate to check in the request, and then export the request in DER format. The request will then need to be sent to the OCSP responder, which needs to be done by the application (GnuTLS does not send and receive OCSP packets). Normally an OCSP response is received that the application will need to import into an OCSP response object. The digital signature in the OCSP response needs to be verified against a set of trust anchors before the information in the response can be trusted.

The ASN.1 structure of OCSP requests are briefly as follows. It is useful to review the structures to get an understanding of which fields are modified by GnuTLS functions.

OCSPRequest     ::=     SEQUENCE {
    tbsRequest                  TBSRequest,
    optionalSignature   [0]     EXPLICIT Signature OPTIONAL }

TBSRequest      ::=     SEQUENCE {
    version             [0]     EXPLICIT Version DEFAULT v1,
    requestorName       [1]     EXPLICIT GeneralName OPTIONAL,
    requestList                 SEQUENCE OF Request,
    requestExtensions   [2]     EXPLICIT Extensions OPTIONAL }

Request         ::=     SEQUENCE {
    reqCert                     CertID,
    singleRequestExtensions     [0] EXPLICIT Extensions OPTIONAL }

CertID          ::=     SEQUENCE {
    hashAlgorithm       AlgorithmIdentifier,
    issuerNameHash      OCTET STRING, -- Hash of Issuer's DN
    issuerKeyHash       OCTET STRING, -- Hash of Issuers public key
    serialNumber        CertificateSerialNumber }

The basic functions to initialize, import, export and deallocate OCSP requests are the following.

gnutls_ocsp_req_init

gnutls_ocsp_req_deinit

gnutls_ocsp_req_import

gnutls_ocsp_req_export

gnutls_ocsp_req_print

There are two interfaces for setting the identity of a certificate in a OCSP request, the first being a low-level function when you have the issuer name hash, issuer key hash, and certificate serial number in binary form. The second is usually more useful if you have the certificate (and its issuer) in a gnutls_x509_crt_t type. There is also a function to extract this information from an OCSP request.

gnutls_ocsp_req_add_cert_id

gnutls_ocsp_req_add_cert

gnutls_ocsp_req_get_cert_id

Each OCSP request may contain a number of extensions. Extensions are identified by an Object Identifier (OID) and an opaque data buffer whose syntax and semantics is implied by the OID.

gnutls_ocsp_req_get_extension

gnutls_ocsp_req_set_extension

A common OCSP Request extension is the nonce extension (OID 1.3.6.1.5.5.7.48.1.2), which is used to avoid replay attacks of earlier recorded OCSP responses. The nonce extension carries a value that is intended to be sufficiently random and unique so that an attacker will not be able to give a stale response for the same nonce.

gnutls_ocsp_req_get_nonce

gnutls_ocsp_req_set_nonce

gnutls_ocsp_req_randomize_nonce

The OCSP response structures is a bit more complex than the request. The important ASN.1 structure is as follows. In practice, all OCSP responses contain a Basic OCSP response sub-structure.

OCSPResponse ::= SEQUENCE {
   responseStatus         OCSPResponseStatus,
   responseBytes          [0] EXPLICIT ResponseBytes OPTIONAL }

OCSPResponseStatus ::= ENUMERATED {
    successful            (0),  --Response has valid confirmations
    malformedRequest      (1),  --Illegal confirmation request
    internalError         (2),  --Internal error in issuer
    tryLater              (3),  --Try again later
                                --(4) is not used
    sigRequired           (5),  --Must sign the request
    unauthorized          (6)   --Request unauthorized }

ResponseBytes ::=       SEQUENCE {
    responseType   OBJECT IDENTIFIER,
    response       OCTET STRING }

id-pkix-ocsp-basic     OBJECT IDENTIFIER ::= { id-pkix-ocsp 1 }

BasicOCSPResponse       ::= SEQUENCE {
   tbsResponseData      ResponseData,
   signatureAlgorithm   AlgorithmIdentifier,
   signature            BIT STRING,
   certs                [0] EXPLICIT SEQUENCE OF Certificate OPTIONAL }

ResponseData ::= SEQUENCE {
   version              [0] EXPLICIT Version DEFAULT v1,
   responderID              ResponderID,
   producedAt               GeneralizedTime,
   responses                SEQUENCE OF SingleResponse,
   responseExtensions   [1] EXPLICIT Extensions OPTIONAL }

ResponderID ::= CHOICE {
   byName               [1] Name,
   byKey                [2] KeyHash }

KeyHash ::= OCTET STRING -- SHA-1 hash of responder's public key
(excluding the tag and length fields)

SingleResponse ::= SEQUENCE {
   certID                       CertID,
   certStatus                   CertStatus,
   thisUpdate                   GeneralizedTime,
   nextUpdate         [0]       EXPLICIT GeneralizedTime OPTIONAL,
   singleExtensions   [1]       EXPLICIT Extensions OPTIONAL }

CertStatus ::= CHOICE {
    good        [0]     IMPLICIT NULL,
    revoked     [1]     IMPLICIT RevokedInfo,
    unknown     [2]     IMPLICIT UnknownInfo }

RevokedInfo ::= SEQUENCE {
    revocationTime              GeneralizedTime,
    revocationReason    [0]     EXPLICIT CRLReason OPTIONAL }

We provide basic functions for initialization, importing, exporting and deallocating OCSP responses. The Basic OCSP Response structure is automatically parsed when an OCSP Response is imported.

gnutls_ocsp_resp_init

gnutls_ocsp_resp_deinit

gnutls_ocsp_resp_import

gnutls_ocsp_resp_export

gnutls_ocsp_resp_print

The OCSP response needs to be verified against some set of trust anchors before it can be relied upon.

gnutls_ocsp_resp_verify

gnutls_ocsp_resp_verify_direct

Managing encrypted keys

Transferring or storing private keys in plain might not be a good idea. Any access on the keys becomes a fatal compromise. Storing the keys in hardware security modules (see Smart cards and HSMs) could solve the storage problem but it is not always practical or efficient enough. This section describes alternative ways that involve encryption of the private keys to store and transfer.

There are two alternatives to use for key encryption, PKCS #8 and #12 methods of private key encryption. The PKCS #8 method only allows encryption of the private key, whilst the PKCS #12 method allows in addition the bundling of other data into the structure. That could be bundling together the certificate as well as the trusted CA certificate.

PKCS #8 structures

PKCS #8 keys can be imported and exported as normal private keys using the functions below. An addition to the normal import functions, are a password and a flags argument. The flags can be any element of the gnutls_pkcs_encrypt_flags_t enumeration. Note however, that GnuTLS only supports the PKCS #5 PBES2 encryption scheme. Keys encrypted with the obsolete PBES1 scheme cannot be decrypted.

gnutls_x509_privkey_import_pkcs8

gnutls_x509_privkey_export_pkcs8

GNUTLS_PKCS_PLAIN

Unencrypted private key.

GNUTLS_PKCS8_PLAIN

Same as GNUTLS_PKCS_PLAIN .

GNUTLS_PKCS_USE_PKCS12_3DES

PKCS-12 3DES.

GNUTLS_PKCS8_USE_PKCS12_3DES

Same as GNUTLS_PKCS_USE_PKCS12_3DES .

GNUTLS_PKCS_USE_PKCS12_ARCFOUR

PKCS-12 ARCFOUR.

GNUTLS_PKCS8_USE_PKCS12_ARCFOUR

Same as GNUTLS_PKCS_USE_PKCS12_ARCFOUR .

GNUTLS_PKCS_USE_PKCS12_RC2_40

PKCS-12 RC2-40.

GNUTLS_PKCS8_USE_PKCS12_RC2_40

Same as GNUTLS_PKCS_USE_PKCS12_RC2_40 .

GNUTLS_PKCS_USE_PBES2_3DES

PBES2 3DES.

GNUTLS_PKCS_USE_PBES2_AES_128

PBES2 AES-128.

GNUTLS_PKCS_USE_PBES2_AES_192

PBES2 AES-192.

GNUTLS_PKCS_USE_PBES2_AES_256

PBES2 AES-256.

PKCS #12 structures

A PKCS #12 structure [PKCS12] usually contains a user’s private keys and certificates. It is commonly used in browsers to export and import the user’s identities.

In GnuTLS the PKCS #12 structures are handled using the gnutls_pkcs12_t type. This is an abstract type that may hold several gnutls_pkcs12_bag_t types. The bag types are the holders of the actual data, which may be certificates, private keys or encrypted data. A bag of type encrypted should be decrypted in order for its data to be accessed.

The following functions are available to read a PKCS #12 structure.

gnutls_pkcs12_get_bag

gnutls_pkcs12_verify_mac

gnutls_pkcs12_bag_decrypt

gnutls_pkcs12_bag_get_count

gnutls_pkcs12_bag_get_data

gnutls_pkcs12_bag_get_key_id

gnutls_pkcs12_bag_get_friendly_name

The functions below are used to generate a PKCS #12 structure. An example of their usage is also shown.

gnutls_pkcs12_set_bag

gnutls_pkcs12_bag_encrypt

gnutls_pkcs12_generate_mac

gnutls_pkcs12_bag_set_data

gnutls_pkcs12_bag_set_crl

gnutls_pkcs12_bag_set_crt

gnutls_pkcs12_bag_set_key_id

gnutls_pkcs12_bag_set_friendly_name

/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <gnutls/gnutls.h>
#include <gnutls/pkcs12.h>

#include "examples.h"

#define OUTFILE "out.p12"

/* This function will write a pkcs12 structure into a file.
 * cert: is a DER encoded certificate
 * pkcs8_key: is a PKCS #8 encrypted key (note that this must be
 *  encrypted using a PKCS #12 cipher, or some browsers will crash)
 * password: is the password used to encrypt the PKCS #12 packet.
 */
int
write_pkcs12 (const gnutls_datum_t * cert,
              const gnutls_datum_t * pkcs8_key, const char *password)
{
  gnutls_pkcs12_t pkcs12;
  int ret, bag_index;
  gnutls_pkcs12_bag_t bag, key_bag;
  char pkcs12_struct[10 * 1024];
  size_t pkcs12_struct_size;
  FILE *fd;

  /* A good idea might be to use gnutls_x509_privkey_get_key_id()
   * to obtain a unique ID.
   */
  gnutls_datum_t key_id = { (void *) "\x00\x00\x07", 3 };

  gnutls_global_init ();

  /* Firstly we create two helper bags, which hold the certificate,
   * and the (encrypted) key.
   */

  gnutls_pkcs12_bag_init (&bag);
  gnutls_pkcs12_bag_init (&key_bag);

  ret = gnutls_pkcs12_bag_set_data (bag, GNUTLS_BAG_CERTIFICATE, cert);
  if (ret < 0)
    {
      fprintf (stderr, "ret: %s\n", gnutls_strerror (ret));
      return 1;
    }

  /* ret now holds the bag's index.
   */
  bag_index = ret;

  /* Associate a friendly name with the given certificate. Used
   * by browsers.
   */
  gnutls_pkcs12_bag_set_friendly_name (bag, bag_index, "My name");

  /* Associate the certificate with the key using a unique key
   * ID.
   */
  gnutls_pkcs12_bag_set_key_id (bag, bag_index, &key_id);

  /* use weak encryption for the certificate.
   */
  gnutls_pkcs12_bag_encrypt (bag, password, GNUTLS_PKCS_USE_PKCS12_RC2_40);

  /* Now the key.
   */

  ret = gnutls_pkcs12_bag_set_data (key_bag,
                                    GNUTLS_BAG_PKCS8_ENCRYPTED_KEY,
                                    pkcs8_key);
  if (ret < 0)
    {
      fprintf (stderr, "ret: %s\n", gnutls_strerror (ret));
      return 1;
    }

  /* Note that since the PKCS #8 key is already encrypted we don't
   * bother encrypting that bag.
   */
  bag_index = ret;

  gnutls_pkcs12_bag_set_friendly_name (key_bag, bag_index, "My name");

  gnutls_pkcs12_bag_set_key_id (key_bag, bag_index, &key_id);

  /* The bags were filled. Now create the PKCS #12 structure.
   */
  gnutls_pkcs12_init (&pkcs12);

  /* Insert the two bags in the PKCS #12 structure.
   */

  gnutls_pkcs12_set_bag (pkcs12, bag);
  gnutls_pkcs12_set_bag (pkcs12, key_bag);

  /* Generate a message authentication code for the PKCS #12
   * structure.
   */
  gnutls_pkcs12_generate_mac (pkcs12, password);

  pkcs12_struct_size = sizeof (pkcs12_struct);
  ret =
    gnutls_pkcs12_export (pkcs12, GNUTLS_X509_FMT_DER, pkcs12_struct,
                          &pkcs12_struct_size);
  if (ret < 0)
    {
      fprintf (stderr, "ret: %s\n", gnutls_strerror (ret));
      return 1;
    }

  fd = fopen (OUTFILE, "w");
  if (fd == NULL)
    {
      fprintf (stderr, "cannot open file\n");
      return 1;
    }
  fwrite (pkcs12_struct, 1, pkcs12_struct_size, fd);
  fclose (fd);

  gnutls_pkcs12_bag_deinit (bag);
  gnutls_pkcs12_bag_deinit (key_bag);
  gnutls_pkcs12_deinit (pkcs12);

  return 0;
}

Invoking certtool

Tool to parse and generate X.509 certificates, requests and private keys. It can be used interactively or non interactively by specifying the template command line option.

This section was generated by AutoGen, using the agtexi-cmd template and the option descriptions for the certtool program. This software is released under the GNU General Public License, version 3 or later.

certtool usage (-h)

This is the automatically generated usage text for certtool:

certtool - GnuTLS PKCS #11 tool - Ver. @VERSION@
USAGE:  certtool [ -<flag> [<val>] | --<name>[{=| }<val>] ]...

   -d, --debug=num            Enable debugging.
                                - It must be in the range:
                                  0 to 9999
       --infile=file          Input file
                                - file must pre-exist
       --outfile=str          Output file
   -s, --generate-self-signed  Generate a self-signed certificate
   -c, --generate-certificate  Generate a signed certificate
       --generate-proxy       Generates a proxy certificate
       --generate-crl         Generate a CRL
   -u, --update-certificate   Update a signed certificate
   -p, --generate-privkey     Generate a private key
   -q, --generate-request     Generate a PKCS #10 certificate request
   -e, --verify-chain         Verify a PEM encoded certificate chain.
       --verify               Verify a PEM encoded certificate chain using a trusted list.
                                - requires these options:
                                load-ca-certificate
       --verify-crl           Verify a CRL using a trusted list.
                                - requires these options:
                                load-ca-certificate
       --generate-dh-params   Generate PKCS #3 encoded Diffie-Hellman parameters.
       --get-dh-params        Get the included PKCS #3 encoded Diffie-Hellman parameters.
       --dh-info              Print information PKCS #3 encoded Diffie-Hellman parameters
       --load-privkey=str     Loads a private key file
       --load-pubkey=str      Loads a public key file
       --load-request=file    Loads a certificate request file
                                - file must pre-exist
       --load-certificate=str Loads a certificate file
       --load-ca-privkey=str  Loads the certificate authority's private key file
       --load-ca-certificate=str Loads the certificate authority's certificate file
       --password=str         Password to use
   -i, --certificate-info     Print information on the given certificate
       --certificate-pubkey   Print certificate's public key
       --pgp-certificate-info  Print information on the given OpenPGP certificate
       --pgp-ring-info        Print information on the given OpenPGP keyring structure
   -l, --crl-info             Print information on the given CRL structure
       --crq-info             Print information on the given certificate request
       --no-crq-extensions    Do not use extensions in certificate requests
       --p12-info             Print information on a PKCS #12 structure
       --p7-info              Print information on a PKCS #7 structure
       --smime-to-p7          Convert S/MIME to PKCS #7 structure
   -k, --key-info             Print information on a private key
       --pgp-key-info         Print information on an OpenPGP private key
       --pubkey-info          Print information on a public key
       --v1                   Generate an X.509 version 1 certificate (with no extensions)
       --to-p12               Generate a PKCS #12 structure
                                - requires these options:
                                load-certificate
                                load-privkey
       --to-p8                Generate a PKCS #8 structure
   -8, --pkcs8                Use PKCS #8 format for private keys
       --rsa                  Generate RSA key
       --dsa                  Generate DSA key
       --ecc                  Generate ECC (ECDSA) key
       --hash=str             Hash algorithm to use for signing.
       --inder                Use DER format for input certificates and private keys.
                                - disabled as --no-inder
       --inraw                This is an alias for 'inder'
       --outder               Use DER format for output certificates and private keys
                                - disabled as --no-outder
       --outraw               This is an alias for 'outder'
       --bits=num             Specify the number of bits for key generate
       --sec-param=str        Specify the security level [low, legacy, normal, high, ultra].
       --disable-quick-random  No effect
       --template=file        Template file to use for non-interactive operation
                                - file must pre-exist
       --pkcs-cipher=str      Cipher to use for PKCS #8 and #12 operations
   -v, --version[=arg]        Output version information and exit
   -h, --help                 Display extended usage information and exit
   -!, --more-help            Extended usage information passed thru pager

Options are specified by doubled hyphens and their name or by a single
hyphen and the flag character.

Tool to parse and generate X.509 certificates, requests and private keys.
It can be used interactively or non interactively by specifying the
template command line option.

please send bug reports to:  bug-gnutls@gnu.org

bits option

This is the “specify the number of bits for key generate” option.

certificate-info option (-i)

This is the “print information on the given certificate” option.

certificate-pubkey option

This is the “print certificate’s public key” option.

crl-info option (-l)

This is the “print information on the given crl structure” option.

crq-info option

This is the “print information on the given certificate request” option.

debug option (-d)

This is the “enable debugging.” option. Specifies the debug level.

dh-info option

This is the “print information pkcs #3 encoded diffie-hellman parameters” option.

disable-quick-random option

This is the “no effect” option.

dsa option

This is the “generate dsa key” option.

ecc option

This is the “generate ecc (ecdsa) key” option.

generate-certificate option (-c)

This is the “generate a signed certificate” option.

generate-crl option

This is the “generate a crl” option.

generate-dh-params option

This is the “generate pkcs #3 encoded diffie-hellman parameters.” option.

generate-privkey option (-p)

This is the “generate a private key” option.

generate-proxy option

This is the “generates a proxy certificate” option.

generate-request option (-q)

This is the “generate a pkcs #10 certificate request” option.

generate-self-signed option (-s)

This is the “generate a self-signed certificate” option.

get-dh-params option

This is the “get the included pkcs #3 encoded diffie-hellman parameters.” option. Returns stored DH parameters in GnuTLS. Those parameters are used in the SRP protocol. The parameters returned by fresh generation are more efficient since GnuTLS 3.0.9.

hash option

This is the “hash algorithm to use for signing.” option. Available hash functions are SHA1, RMD160, SHA256, SHA384, SHA512.

inder option

This is the “use der format for input certificates and private keys.” option. The input files will be assumed to be in DER or RAW format. Unlike options that in PEM input would allow multiple input data (e.g. multiple certificates), when reading in DER format a single data structure is read.

infile option

This is the “input file” option.

inraw option

This is an alias for the inder option, see the inder documentation.

key-info option (-k)

This is the “print information on a private key” option.

load-ca-certificate option

This is the “loads the certificate authority’s certificate file” option. This can be either a file or a PKCS #11 URL

load-ca-privkey option

This is the “loads the certificate authority’s private key file” option. This can be either a file or a PKCS #11 URL

load-certificate option

This is the “loads a certificate file” option. This can be either a file or a PKCS #11 URL

load-privkey option

This is the “loads a private key file” option. This can be either a file or a PKCS #11 URL

load-pubkey option

This is the “loads a public key file” option. This can be either a file or a PKCS #11 URL

load-request option

This is the “loads a certificate request file” option.

no-crq-extensions option

This is the “do not use extensions in certificate requests” option.

outder option

This is the “use der format for output certificates and private keys” option. The output will be in DER or RAW format.

outfile option

This is the “output file” option.

outraw option

This is an alias for the outder option, see the outder documentation.

p12-info option

This is the “print information on a pkcs #12 structure” option.

p7-info option

This is the “print information on a pkcs #7 structure” option.

password option

This is the “password to use” option.

pgp-certificate-info option

This is the “print information on the given openpgp certificate” option.

pgp-key-info option

This is the “print information on an openpgp private key” option.

pgp-ring-info option

This is the “print information on the given openpgp keyring structure” option.

pkcs-cipher option

This is the “cipher to use for pkcs #8 and #12 operations” option. Cipher may be one of 3des, 3des-pkcs12, aes-128, aes-192, aes-256, rc2-40, arcfour.

pkcs8 option (-8)

This is the “use pkcs #8 format for private keys” option.

pubkey-info option

This is the “print information on a public key” option.

rsa option

This is the “generate rsa key” option.

sec-param option

This is the “specify the security level [low, legacy, normal, high, ultra].” option. This is alternative to the bits option.

smime-to-p7 option

This is the “convert s/mime to pkcs #7 structure” option.

template option

This is the “template file to use for non-interactive operation” option.

to-p12 option

This is the “generate a pkcs #12 structure” option.

This option has some usage constraints. It:

must appear in combination with the following options: load-certificate, load-privkey.

It requires a certificate, a private key and possibly a CA certificate to be specified.

to-p8 option

This is the “generate a pkcs #8 structure” option.

update-certificate option (-u)

This is the “update a signed certificate” option.

v1 option

This is the “generate an x.509 version 1 certificate (with no extensions)” option.

verify option

This is the “verify a pem encoded certificate chain using a trusted list.” option.

This option has some usage constraints. It:

must appear in combination with the following options: load-ca-certificate.

The trusted certificate list must be loaded with –load-ca-certificate.

verify-chain option (-e)

This is the “verify a pem encoded certificate chain.” option. The last certificate in the chain must be a self signed one.

verify-crl option

This is the “verify a crl using a trusted list.” option.

This option has some usage constraints. It:

must appear in combination with the following options: load-ca-certificate.

The trusted certificate list must be loaded with –load-ca-certificate.

certtool exit status

One of the following exit values will be returned:

‘0’

Successful program execution.

‘1’

The operation failed or the command syntax was not valid.

certtool See Also

p11tool (1)

certtool Examples

Generating private keys

To create an RSA private key, run:

$ certtool --generate-privkey --outfile key.pem --rsa

To create a DSA or elliptic curves (ECDSA) private key use the above command combined with ’dsa’ or ’ecc’ options.

Generating certificate requests

To create a certificate request (needed when the certificate is issued by another party), run:

certtool --generate-request --load-privkey key.pem \
   --outfile request.pem

If the private key is stored in a smart card you can generate a request by specifying the private key object URL.

$ ./certtool --generate-request --load-privkey "pkcs11:..." \
  --load-pubkey "pkcs11:..." --outfile request.pem

Generating a self-signed certificate

To create a self signed certificate, use the command:

$ certtool --generate-privkey --outfile ca-key.pem
$ certtool --generate-self-signed --load-privkey ca-key.pem \
   --outfile ca-cert.pem

Note that a self-signed certificate usually belongs to a certificate authority, that signs other certificates.

Generating a certificate

To generate a certificate using the previous request, use the command:

$ certtool --generate-certificate --load-request request.pem \
   --outfile cert.pem --load-ca-certificate ca-cert.pem \
   --load-ca-privkey ca-key.pem

To generate a certificate using the private key only, use the command:

$ certtool --generate-certificate --load-privkey key.pem \
   --outfile cert.pem --load-ca-certificate ca-cert.pem \
   --load-ca-privkey ca-key.pem

Certificate information

To view the certificate information, use:

$ certtool --certificate-info --infile cert.pem

PKCS #12 structure generation

To generate a PKCS #12 structure using the previous key and certificate, use the command:

$ certtool --load-certificate cert.pem --load-privkey key.pem \
   --to-p12 --outder --outfile key.p12

Some tools (reportedly web browsers) have problems with that file because it does not contain the CA certificate for the certificate. To work around that problem in the tool, you can use the –load-ca-certificate parameter as follows:

$ certtool --load-ca-certificate ca.pem \
  --load-certificate cert.pem --load-privkey key.pem \
  --to-p12 --outder --outfile key.p12

Diffie-Hellman parameter generation

To generate parameters for Diffie-Hellman key exchange, use the command:

$ certtool --generate-dh-params --outfile dh.pem --sec-param normal

Proxy certificate generation

Proxy certificate can be used to delegate your credential to a temporary, typically short-lived, certificate. To create one from the previously created certificate, first create a temporary key and then generate a proxy certificate for it, using the commands:

$ certtool --generate-privkey > proxy-key.pem
$ certtool --generate-proxy --load-ca-privkey key.pem \
  --load-privkey proxy-key.pem --load-certificate cert.pem \
  --outfile proxy-cert.pem

Certificate revocation list generation

To create an empty Certificate Revocation List (CRL) do:

$ certtool --generate-crl --load-ca-privkey x509-ca-key.pem \
           --load-ca-certificate x509-ca.pem

To create a CRL that contains some revoked certificates, place the certificates in a file and use --load-certificate as follows:

$ certtool --generate-crl --load-ca-privkey x509-ca-key.pem \
  --load-ca-certificate x509-ca.pem --load-certificate revoked-certs.pem

To verify a Certificate Revocation List (CRL) do:

$ certtool --verify-crl --load-ca-certificate x509-ca.pem < crl.pem

certtool Files

Certtool’s template file format

A template file can be used to avoid the interactive questions of certtool. Initially create a file named ’cert.cfg’ that contains the information about the certificate. The template can be used as below:

$ certtool --generate-certificate cert.pem --load-privkey key.pem  \
   --template cert.cfg \
   --load-ca-certificate ca-cert.pem --load-ca-privkey ca-key.pem

An example certtool template file that can be used to generate a certificate request or a self signed certificate follows.

# X.509 Certificate options
#
# DN options

# The organization of the subject.
organization = "Koko inc."

# The organizational unit of the subject.
unit = "sleeping dept."

# The locality of the subject.
# locality =

# The state of the certificate owner.
state = "Attiki"

# The country of the subject. Two letter code.
country = GR

# The common name of the certificate owner.
cn = "Cindy Lauper"

# A user id of the certificate owner.
#uid = "clauper"

# Set domain components
#dc = "name"
#dc = "domain"

# If the supported DN OIDs are not adequate you can set
# any OID here.
# For example set the X.520 Title and the X.520 Pseudonym
# by using OID and string pairs.
#dn_oid = 2.5.4.12 Dr.
#dn_oid = 2.5.4.65 jackal

# This is deprecated and should not be used in new
# certificates.
# pkcs9_email = "none@none.org"

# The serial number of the certificate
serial = 007

# In how many days, counting from today, this certificate will expire.
expiration_days = 700

# X.509 v3 extensions

# A dnsname in case of a WWW server.
#dns_name = "www.none.org"
#dns_name = "www.morethanone.org"

# An IP address in case of a server.
#ip_address = "192.168.1.1"

# An email in case of a person
email = "none@none.org"

# Challenge password used in certificate requests
challenge_passwd = 123456

# An URL that has CRLs (certificate revocation lists)
# available. Needed in CA certificates.
#crl_dist_points = "http://www.getcrl.crl/getcrl/"

# Whether this is a CA certificate or not
#ca

# for microsoft smart card logon
# key_purpose_oid = 1.3.6.1.4.1.311.20.2.2

### Other predefined key purpose OIDs

# Whether this certificate will be used for a TLS client
#tls_www_client

# Whether this certificate will be used for a TLS server
#tls_www_server

# Whether this certificate will be used to sign data (needed
# in TLS DHE ciphersuites).
signing_key

# Whether this certificate will be used to encrypt data (needed
# in TLS RSA ciphersuites). Note that it is preferred to use different
# keys for encryption and signing.
#encryption_key

# Whether this key will be used to sign other certificates.
#cert_signing_key

# Whether this key will be used to sign CRLs.
#crl_signing_key

# Whether this key will be used to sign code.
#code_signing_key

# Whether this key will be used to sign OCSP data.
#ocsp_signing_key

# Whether this key will be used for time stamping.
#time_stamping_key

# Whether this key will be used for IPsec IKE operations.
#ipsec_ike_key

### end of key purpose OIDs

# When generating a certificate from a certificate
# request, then honor the extensions stored in the request
# and store them in the real certificate.
#honor_crq_extensions

# Path length contraint. Sets the maximum number of
# certificates that can be used to certify this certificate.
# (i.e. the certificate chain length)
#path_len = -1
#path_len = 2

# OCSP URI
# ocsp_uri = http://my.ocsp.server/ocsp

# CA issuers URI
# ca_issuers_uri = http://my.ca.issuer

# Options for proxy certificates
# proxy_policy_language = 1.3.6.1.5.5.7.21.1

# Options for generating a CRL

# next CRL update will be in 43 days (wow)
#crl_next_update = 43

# this is the 5th CRL by this CA
#crl_number = 5

Invoking ocsptool

Ocsptool is a program that can parse and print information about OCSP requests/responses, generate requests and verify responses.

This section was generated by AutoGen, using the agtexi-cmd template and the option descriptions for the ocsptool program. This software is released under the GNU General Public License, version 3 or later.

ocsptool usage (-h)

This is the automatically generated usage text for ocsptool:

ocsptool - GnuTLS OCSP tool - Ver. @VERSION@
USAGE:  ocsptool [ -<flag> [<val>] | --<name>[{=| }<val>] ]...

   -d, --debug=num            Enable debugging.
                                - It must be in the range:
                                  0 to 9999
   -V, --verbose              More verbose output
                                - may appear multiple times
       --infile=file          Input file
                                - file must pre-exist
       --outfile=str          Output file
       --ask[=arg]            Ask an OCSP/HTTP server on a certificate validity
                                - requires these options:
                                load-cert
                                load-issuer
   -e, --verify-response      Verify response
   -i, --request-info         Print information on a OCSP request
   -j, --response-info        Print information on a OCSP response
   -q, --generate-request     Generate an OCSP request
       --nonce                Don't add nonce to OCSP request
                                - disabled as --no-nonce
       --load-issuer=file     Read issuer certificate from file
                                - file must pre-exist
       --load-cert=file       Read certificate to check from file
                                - file must pre-exist
       --load-trust=file      Read OCSP trust anchors from file
                                - prohibits these options:
                                load-signer
                                - file must pre-exist
       --load-signer=file     Read OCSP response signer from file
                                - prohibits these options:
                                load-trust
                                - file must pre-exist
       --inder                Use DER format for input certificates and private keys
                                - disabled as --no-inder
   -Q, --load-request=file    Read DER encoded OCSP request from file
                                - file must pre-exist
   -S, --load-response=file   Read DER encoded OCSP response from file
                                - file must pre-exist
   -v, --version[=arg]        Output version information and exit
   -h, --help                 Display extended usage information and exit
   -!, --more-help            Extended usage information passed thru pager

Options are specified by doubled hyphens and their name or by a single
hyphen and the flag character.

Ocsptool is a program that can parse and print information about OCSP
requests/responses, generate requests and verify responses.

please send bug reports to:  bug-gnutls@gnu.org

ask option

This is the “ask an ocsp/http server on a certificate validity” option.

This option has some usage constraints. It:

must appear in combination with the following options: load-cert, load-issuer.

Connects to the specified HTTP OCSP server and queries on the validity of the loaded certificate.

debug option (-d)

This is the “enable debugging.” option. Specifies the debug level.

generate-request option (-q)

This is the “generate an ocsp request” option.

inder option

This is the “use der format for input certificates and private keys” option.

infile option

This is the “input file” option.

load-cert option

This is the “read certificate to check from file” option.

load-issuer option

This is the “read issuer certificate from file” option.

load-request option (-Q)

This is the “read der encoded ocsp request from file” option.

load-response option (-S)

This is the “read der encoded ocsp response from file” option.

load-signer option

This is the “read ocsp response signer from file” option.

This option has some usage constraints. It:

must not appear in combination with any of the following options: load-trust.

load-trust option

This is the “read ocsp trust anchors from file” option.

This option has some usage constraints. It:

must not appear in combination with any of the following options: load-signer.

nonce option

This is the “don’t add nonce to ocsp request” option.

outfile option

This is the “output file” option.

request-info option (-i)

This is the “print information on a ocsp request” option.

response-info option (-j)

This is the “print information on a ocsp response” option.

verbose option (-V)

This is the “more verbose output” option.

This option has some usage constraints. It:

may appear an unlimited number of times.

verify-response option (-e)

This is the “verify response” option.

ocsptool exit status

One of the following exit values will be returned:

‘0’

Successful program execution.

‘1’

The operation failed or the command syntax was not valid.

ocsptool See Also

certtool (1)

ocsptool Examples

Print information about an OCSP request

To parse an OCSP request and print information about the content, the -i or --request-info parameter may be used as follows. The -Q parameter specify the name of the file containing the OCSP request, and it should contain the OCSP request in binary DER format.

$ ocsptool -i -Q ocsp-request.der

The input file may also be sent to standard input like this:

$ cat ocsp-request.der | ocsptool --request-info

Print information about an OCSP response

Similar to parsing OCSP requests, OCSP responses can be parsed using the -j or --response-info as follows.

$ ocsptool -j -Q ocsp-response.der
$ cat ocsp-response.der | ocsptool --response-info

Generate an OCSP request

The -q or --generate-request parameters are used to generate an OCSP request. By default the OCSP request is written to standard output in binary DER format, but can be stored in a file using --outfile. To generate an OCSP request the issuer of the certificate to check needs to be specified with --load-issuer and the certificate to check with --load-cert. By default PEM format is used for these files, although --inder can be used to specify that the input files are in DER format.

$ ocsptool -q --load-issuer issuer.pem --load-cert client.pem \
           --outfile ocsp-request.der

When generating OCSP requests, the tool will add an OCSP extension containing a nonce. This behaviour can be disabled by specifying --no-nonce.

Verify signature in OCSP response

To verify the signature in an OCSP response the -e or --verify-response parameter is used. The tool will read an OCSP response in DER format from standard input, or from the file specified by --load-response. The OCSP response is verified against a set of trust anchors, which are specified using --load-trust. The trust anchors are concatenated certificates in PEM format. The certificate that signed the OCSP response needs to be in the set of trust anchors, or the issuer of the signer certificate needs to be in the set of trust anchors and the OCSP Extended Key Usage bit has to be asserted in the signer certificate.

$ ocsptool -e --load-trust issuer.pem \
           --load-response ocsp-response.der

The tool will print status of verification.

Verify signature in OCSP response against given certificate

It is possible to override the normal trust logic if you know that a certain certificate is supposed to have signed the OCSP response, and you want to use it to check the signature. This is achieved using --load-signer instead of --load-trust. This will load one certificate and it will be used to verify the signature in the OCSP response. It will not check the Extended Key Usage bit.

$ ocsptool -e --load-signer ocsp-signer.pem \
           --load-response ocsp-response.der

This approach is normally only relevant in two situations. The first is when the OCSP response does not contain a copy of the signer certificate, so the --load-trust code would fail. The second is if you want to avoid the indirect mode where the OCSP response signer certificate is signed by a trust anchor.

Real-world example

Here is an example of how to generate an OCSP request for a certificate and to verify the response. For illustration we’ll use the blog.josefsson.org host, which (as of writing) uses a certificate from CACert. First we’ll use gnutls-cli to get a copy of the server certificate chain. The server is not required to send this information, but this particular one is configured to do so.

$ echo | gnutls-cli -p 443 blog.josefsson.org --print-cert > chain.pem

Use a text editor on chain.pem to create three files for each separate certificates, called cert.pem for the first certificate for the domain itself, secondly issuer.pem for the intermediate certificate and root.pem for the final root certificate.

The domain certificate normally contains a pointer to where the OCSP responder is located, in the Authority Information Access Information extension. For example, from certtool -i < cert.pem there is this information:

Authority Information Access Information (not critical):
Access Method: 1.3.6.1.5.5.7.48.1 (id-ad-ocsp)
Access Location URI: http://ocsp.CAcert.org/

This means the CA support OCSP queries over HTTP. We are now ready to create a OCSP request for the certificate.

$ ocsptool --ask ocsp.CAcert.org --load-issuer issuer.pem \
           --load-cert cert.pem --outfile ocsp-response.der

The request is sent via HTTP to the OCSP server address specified. If the address is ommited ocsptool will use the address stored in the certificate.

Smart cards and HSMs

In this section we present the smart-card and hardware security module (HSM) support in GnuTLS using PKCS #11 [PKCS11]. Hardware security modules and smart cards provide a way to store private keys and perform operations on them without exposing them. This decouples cryptographic keys from the applications that use them and provide an additional security layer against cryptographic key extraction. Since this can also be achieved in software components such as in Gnome keyring, we will use the term security module to describe any cryptographic key separation subsystem.

PKCS #11 is plugin API allowing applications to access cryptographic operations on a security module, as well as to objects residing on it. PKCS #11 modules exist for hardware tokens such as smart cards[9], the trusted platform module (TPM)[10] as well as for software modules like Gnome Keyring. The objects residing on a security module may be certificates, public keys, private keys or secret keys. Of those certificates and public/private key pairs can be used with GnuTLS. PKCS #11’s main advantage is that it allows operations on private key objects such as decryption and signing without exposing the key.

Moreover PKCS #11 can be (ab)used to allow all applications in the same operating system to access shared cryptographic keys and certificates in a uniform way, as in fig:pkcs11-vision. That way applications could load their trusted certificate list, as well as user certificates from a common PKCS #11 module. Such a provider exists in the Gnome system, being the Gnome Keyring.

Initialization

To allow all the GnuTLS applications to access PKCS #11 tokens you can use a configuration per module, stored in /etc/pkcs11/modules/. These are the configuration files of p11-kit[11]. For example a file that will load the OpenSC module, could be named /etc/pkcs11/modules/opensc and contain the following:

module: /usr/lib/opensc-pkcs11.so

If you use this file, then there is no need for other initialization in GnuTLS, except for the PIN and token functions. Those allow retrieving a PIN when accessing a protected object, such as a private key, as well as probe the user to insert the token. All the initialization functions are below.

gnutls_pkcs11_init

gnutls_pkcs11_set_token_function

gnutls_pkcs11_set_pin_function

gnutls_pkcs11_add_provider

Note that due to limitations of PKCS #11 there are issues when multiple libraries are sharing a module. To avoid this problem GnuTLS uses p11-kit that provides a middleware to control access to resources over the multiple users.

Moreover PKCS #11 modules must be reinitialized on the child processes after a fork. GnuTLS provides gnutls_pkcs11_reinit to be called for this purpose.

gnutls_pkcs11_reinit

Reading objects

All PKCS #11 objects are referenced by GnuTLS functions by URLs as described in [PKCS11URI]. This allows for a consistent naming of objects across systems and applications in the same system. For example a public key on a smart card may be referenced as:

pkcs11:token=Nikos;serial=307521161601031;model=PKCS%2315; \
manufacturer=EnterSafe;object=test1;objecttype=public;\
id=32f153f3e37990b08624141077ca5dec2d15faed

while the smart card itself can be referenced as:

pkcs11:token=Nikos;serial=307521161601031;model=PKCS%2315;manufacturer=EnterSafe

Objects stored in a PKCS #11 token can be extracted if they are not marked as sensitive. Usually only private keys are marked as sensitive and cannot be extracted, while certificates and other data can be retrieved. The functions that can be used to access objects are shown below.

gnutls_pkcs11_obj_import_url

gnutls_pkcs11_obj_export_url

gnutls_pkcs11_obj_get_info

gnutls_x509_crt_import_pkcs11

gnutls_x509_crt_import_pkcs11_url

gnutls_x509_crt_list_import_pkcs11

Properties of the physical token can also be accessed and altered with GnuTLS. For example data in a token can be erased (initialized), PIN can be altered, etc.

gnutls_pkcs11_token_init

gnutls_pkcs11_token_get_url

gnutls_pkcs11_token_get_info

gnutls_pkcs11_token_get_flags

gnutls_pkcs11_token_set_pin

The following examples demonstrate the usage of the API. The first example will list all available PKCS #11 tokens in a system and the latter will list all certificates in a token that have a corresponding private key.

int i;
char* url;

gnutls_global_init();

for (i=0;;i++)
  {
    ret = gnutls_pkcs11_token_get_url(i, &url);
    if (ret == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE)
      break;

    if (ret < 0)
      exit(1);

    fprintf(stdout, "Token[%d]: URL: %s\n", i, url);
    gnutls_free(url);
  }
gnutls_global_deinit();

/* This example code is placed in the public domain. */

#include <config.h>
#include <gnutls/gnutls.h>
#include <gnutls/pkcs11.h>
#include <stdio.h>
#include <stdlib.h>

#define URL "pkcs11:URL"

int
main (int argc, char** argv)
{
  gnutls_pkcs11_obj_t *obj_list;
  gnutls_x509_crt_t xcrt;
  unsigned int obj_list_size = 0;
  gnutls_datum_t cinfo;
  int ret;
  unsigned int i;

  obj_list_size = 0;
  ret = gnutls_pkcs11_obj_list_import_url (NULL, &obj_list_size, URL,
                                       GNUTLS_PKCS11_OBJ_ATTR_CRT_WITH_PRIVKEY,
                                       0);
  if (ret < 0 && ret != GNUTLS_E_SHORT_MEMORY_BUFFER)
    return -1;

/* no error checking from now on */
  obj_list = malloc (sizeof (*obj_list) * obj_list_size);

  gnutls_pkcs11_obj_list_import_url (obj_list, &obj_list_size, URL,
                                     GNUTLS_PKCS11_OBJ_ATTR_CRT_WITH_PRIVKEY,
                                     0);

/* now all certificates are in obj_list */
  for (i = 0; i < obj_list_size; i++)
    {

      gnutls_x509_crt_init (&xcrt);

      gnutls_x509_crt_import_pkcs11 (xcrt, obj_list[i]);

      gnutls_x509_crt_print (xcrt, GNUTLS_CRT_PRINT_FULL, &cinfo);

      fprintf (stdout, "cert[%d]:\n %s\n\n", i, cinfo.data);

      gnutls_free (cinfo.data);
      gnutls_x509_crt_deinit (xcrt);
    }

  return 0;
}

Writing objects

With GnuTLS you can copy existing private keys and certificates to a token. Note that when copying private keys it is recommended to mark them as sensitive using the GNUTLS_PKCS11_OBJ_FLAG_MARK_SENSITIVE to prevent its extraction. An object can be marked as private using the flag GNUTLS_PKCS11_OBJ_FLAG_MARK_PRIVATE, to require PIN to be entered before accessing the object (for operations or otherwise).

gnutls_pkcs11_copy_x509_privkey

gnutls_pkcs11_copy_x509_crt

gnutls_pkcs11_delete_url

Using a PKCS #11 token with TLS

It is possible to use a PKCS #11 token to a TLS session, as shown in ex:pkcs11-client. In addition the following functions can be used to load PKCS #11 key and certificates by specifying a PKCS #11 URL instead of a filename.

gnutls_certificate_set_x509_trust_file

gnutls_certificate_set_x509_key_file

Invoking p11tool

Program that allows handling data from PKCS #11 smart cards and security modules.

To use PKCS #11 tokens with gnutls the configuration file /etc/gnutls/pkcs11.conf has to exist and contain a number of lines of the form ’load=/usr/lib/opensc-pkcs11.so’.

This section was generated by AutoGen, using the agtexi-cmd template and the option descriptions for the p11tool program. This software is released under the GNU General Public License, version 3 or later.

p11tool usage (-h)

This is the automatically generated usage text for p11tool:

p11tool - GnuTLS PKCS #11 tool - Ver. @VERSION@
USAGE:  p11tool [ -<flag> [<val>] | --<name>[{=| }<val>] ]... [url]

   -d, --debug=num            Enable debugging.
                                - It must be in the range:
                                  0 to 9999
       --outfile=str          Output file
       --list-tokens          List all available tokens
       --export               Export the object specified by the URL
       --list-mechanisms      List all available mechanisms in a token
       --list-all             List all available objects in a token
       --list-all-certs       List all available certificates in a token
       --list-certs           List all certificates that have an associated private key
       --list-all-privkeys    List all available private keys in a token
       --list-all-trusted     List all available certificates marked as trusted
       --initialize           Initializes a PKCS #11 token
       --write                Writes the loaded objects to a PKCS #11 token
       --delete               Deletes the objects matching the PKCS #11 URL
       --generate-rsa         Generate an RSA private-public key pair
       --generate-dsa         Generate an RSA private-public key pair
       --generate-ecc         Generate an RSA private-public key pair
       --label=str            Sets a label for the write operation
       --trusted              Marks the object to be written as trusted
                                - disabled as --no-trusted
       --private              Marks the object to be written as private
                                - disabled as --no-private
                                - enabled by default
       --login                Force login to token
                                - disabled as --no-login
       --detailed-url         Print detailed URLs
                                - disabled as --no-detailed-url
       --secret-key=str       Provide a hex encoded secret key
       --load-privkey=file    Private key file to use
                                - file must pre-exist
       --load-pubkey=file     Public key file to use
                                - file must pre-exist
       --load-certificate=file Certificate file to use
                                - file must pre-exist
   -8, --pkcs8                Use PKCS #8 format for private keys
       --bits=num             Specify the number of bits for key generate
       --sec-param=str        Specify the security level
       --inder                Use DER/RAW format for input
                                - disabled as --no-inder
       --inraw                This is an alias for 'inder'
       --provider=file        Specify the PKCS #11 provider library
                                - file must pre-exist
   -v, --version[=arg]        Output version information and exit
   -h, --help                 Display extended usage information and exit
   -!, --more-help            Extended usage information passed thru pager

Options are specified by doubled hyphens and their name or by a single
hyphen and the flag character.
Operands and options may be intermixed.  They will be reordered.

Program that allows handling data from PKCS #11 smart cards and security
modules.

To use PKCS #11 tokens with gnutls the configuration file
/etc/gnutls/pkcs11.conf has to exist and contain a number of lines of
the form 'load=/usr/lib/opensc-pkcs11.so'.

please send bug reports to:  bug-gnutls@gnu.org

bits option

This is the “specify the number of bits for key generate” option.

debug option (-d)

This is the “enable debugging.” option. Specifies the debug level.

delete option

This is the “deletes the objects matching the pkcs #11 url” option.

detailed-url option

This is the “print detailed urls” option.

export option

This is the “export the object specified by the url” option.

generate-dsa option

This is the “generate an rsa private-public key pair” option. Generates an RSA private-public key pair on the specified token.

generate-ecc option

This is the “generate an rsa private-public key pair” option. Generates an RSA private-public key pair on the specified token.

generate-rsa option

This is the “generate an rsa private-public key pair” option. Generates an RSA private-public key pair on the specified token.

inder option

This is the “use der/raw format for input” option. Use DER/RAW format for input certificates and private keys.

initialize option

This is the “initializes a pkcs #11 token” option.

inraw option

This is an alias for the inder option, see the inder documentation.

label option

This is the “sets a label for the write operation” option.

list-all option

This is the “list all available objects in a token” option.

list-all-certs option

This is the “list all available certificates in a token” option.

list-all-privkeys option

This is the “list all available private keys in a token” option.

list-all-trusted option

This is the “list all available certificates marked as trusted” option.

list-certs option

This is the “list all certificates that have an associated private key” option.

list-mechanisms option

This is the “list all available mechanisms in a token” option.

list-tokens option

This is the “list all available tokens” option.

load-certificate option

This is the “certificate file to use” option.

load-privkey option

This is the “private key file to use” option.

load-pubkey option

This is the “public key file to use” option.

login option

This is the “force login to token” option.

outfile option

This is the “output file” option.

pkcs8 option (-8)

This is the “use pkcs #8 format for private keys” option.

private option

This is the “marks the object to be written as private” option.

This option has some usage constraints. It:

is enabled by default.

The written object will require a PIN to be used.

provider option

This is the “specify the pkcs #11 provider library” option. This will override the default options in /etc/gnutls/pkcs11.conf

sec-param option

This is the “specify the security level” option. This is alternative to the bits option. Available options are [low, legacy, normal, high, ultra].

secret-key option

This is the “provide a hex encoded secret key” option.

trusted option

This is the “marks the object to be written as trusted” option.

write option

This is the “writes the loaded objects to a pkcs #11 token” option. It can be used to write private keys, certificates or secret keys to a token.

p11tool exit status

One of the following exit values will be returned:

‘0’

Successful program execution.

‘1’

The operation failed or the command syntax was not valid.

p11tool See Also

certtool (1)

p11tool Examples

To view all tokens in your system use:

$ p11tool --list-tokens

To view all objects in a token use:

$ p11tool --login --list-all "pkcs11:TOKEN-URL"

To store a private key and a certificate in a token run:

$ p11tool --login --write "pkcs11:URL" --load-privkey key.pem \
          --label "Mykey"
$ p11tool --login --write "pkcs11:URL" --load-certificate cert.pem \
          --label "Mykey"

Note that some tokens require the same label to be used for the certificate and its corresponding private key.

[9] http://www.opensc-project.org

[10] http://trousers.sourceforge.net/

[11] http://p11-glue.freedesktop.org/

Abstract key types

Since there are many forms of a public or private keys supported by GnuTLS such as X.509, OpenPGP, or PKCS #11 it is desirable to allow common operations on them. For these reasons the abstract gnutls_privkey_t and gnutls_pubkey_t were introduced in gnutls/abstract.h header. Those types are initialized using a specific type of key and then can be used to perform operations in an abstract way. For example in order to sign an X.509 certificate with a key that resides in a token the following steps must be used.

#inlude <gnutls/abstract.h>
#inlude <gnutls/pkcs11.h>

void sign_cert( gnutls_x509_crt_t to_be_signed)
{
gnutls_pkcs11_privkey_t ca_key;
gnutls_x509_crt_t ca_cert;
gnutls_privkey_t abs_key;

  /* load the PKCS #11 key and certificates */
  gnutls_pkcs11_privkey_init(&ca_key);
  gnutls_pkcs11_privkey_import_url(ca_key, key_url);

  gnutls_x509_crt_init(&ca_cert);
  gnutls_x509_crt_import_pkcs11_url(&ca_cert, cert_url);

  /* initialize the abstract key */
  gnutls_privkey_init(&abs_key);
  gnutls_privkey_import_pkcs11(abs_key, ca_key);

  /* sign the certificate to be signed */
  gnutls_x509_crt_privkey_sign(to_be_signed, ca_cert, ca_key,
                               GNUTLS_DIG_SHA256, 0);
}

Public keys

An abstract gnutls_pubkey_t can be initialized using the functions below. It can be imported through an existing structure like gnutls_x509_crt_t, or through an ASN.1 encoding of the X.509 SubjectPublicKeyInfo sequence.

gnutls_pubkey_import_x509

gnutls_pubkey_import_openpgp

gnutls_pubkey_import_pkcs11

gnutls_pubkey_import_pkcs11_url

gnutls_pubkey_import_privkey

gnutls_pubkey_import

gnutls_pubkey_export

Additional functions are available that will return information over a public key.

gnutls_pubkey_get_pk_algorithm

gnutls_pubkey_get_preferred_hash_algorithm

gnutls_pubkey_get_key_id

Private keys

An abstract gnutls_privkey_t can be initialized using the functions below. It can be imported through an existing structure like gnutls_x509_privkey_t, but unlike public keys it cannot be exported. That is to allow abstraction over PKCS #11 keys that are not extractable.

gnutls_privkey_import_x509

gnutls_privkey_import_openpgp

gnutls_privkey_import_pkcs11

gnutls_privkey_get_pk_algorithm

gnutls_privkey_get_type

In order to support cryptographic operations using an external API, the following function is provided. This allows for a simple extensibility API without resorting to PKCS #11.

gnutls_privkey_import_ext

Operations

The abstract key types can be used to access signing and signature verification operations with the underlying keys.

gnutls_pubkey_verify_data2

gnutls_pubkey_verify_hash

gnutls_pubkey_encrypt_data

gnutls_privkey_sign_data

gnutls_privkey_sign_hash

gnutls_privkey_decrypt_data

Signing existing structures, such as certificates, CRLs, or certificate requests, as well as associating public keys with structures is also possible using the key abstractions.

gnutls_x509_crq_set_pubkey

gnutls_x509_crt_set_pubkey

gnutls_x509_crt_privkey_sign

gnutls_x509_crl_privkey_sign

gnutls_x509_crq_privkey_sign

Chapter 7. How to use GnuTLS in applications

Introduction

General idea

A brief description of how GnuTLS works internally is shown at fig:gnutls-design. This section may become more clear after having read the rest of this section. As shown in the figure, there is a read-only global state that is initialized once by the global initialization function. This global structure, among others, contains the memory allocation functions used, and structures needed for the ASN.1 parser. This structure is never modified by any GnuTLS function, except for the deinitialization function which frees all allocated memory and is called after the program has permanently finished using GnuTLS.

The credentials structures are used by the authentication methods, such as certificate authentication. They store certificates, privates keys, and other information that is needed to prove the identity to the peer, and/or verify the indentity of the peer. The information stored in the credentials structures is initialized once and then can be shared by many TLS sessions.

A GnuTLS session contains all the required information to handle one secure connection. The session communicates with the peers using the provided functions of the transport layer. Every session has a unique session ID shared with the peer.

Since TLS sessions can be resumed, servers need a database back-end to hold the session’s parameters. Every GnuTLS session after a successful handshake calls the appropriate back-end function (see resume) to store the newly negotiated session. The session database is examined by the server just after having received the client hello[12], and if the session ID sent by the client, matches a stored session, the stored session will be retrieved, and the new session will be a resumed one, and will share the same session ID with the previous one.

Error handling

In GnuTLS most functions return an integer type as a result. In almost all cases a zero or a positive number means success, and a negative number indicates failure, or a situation that some action has to be taken. Thus negative error codes may be fatal or not.

Fatal errors terminate the connection immediately and further sends and receives will be disallowed. Such an example is GNUTLS_E_DECRYPTION_FAILED. Non-fatal errors may warn about something, i.e., a warning alert was received, or indicate the some action has to be taken. This is the case with the error code GNUTLS_E_REHANDSHAKE returned by gnutls_record_recv. This error code indicates that the server requests a re-handshake. The client may ignore this request, or may reply with an alert. You can test if an error code is a fatal one by using the gnutls_error_is_fatal.

If any non fatal errors, that require an action, are to be returned by a function, these error codes will be documented in the function’s reference. See Error codes, for a description of the available error codes.

Debugging and auditing

In many cases things may not go as expected and further information, to assist debugging, from GnuTLS is desired. Those are the cases where the gnutls_global_set_log_level and gnutls_global_set_log_function are to be used. Those will print verbose information on the GnuTLS functions internal flow.

gnutls_global_set_log_level

gnutls_global_set_log_function

When debugging is not required, important issues, such as detected attacks on the protocol still need to be logged. This is provided by the logging function set by gnutls_global_set_audit_log_function. The provided function will receive an message and the corresponding TLS session. The session information might be used to derive IP addresses or other information about the peer involved.

gnutls_global_set_audit_log_function

Thread safety

The GnuTLS library is thread safe by design, meaning that objects of the library such as TLS sessions, can be safely divided across threads as long as a single thread accesses a single object. This is sufficient to support a server which handles several sessions per thread. If, however, an object needs to be shared across threads then access must be protected with a mutex. Read-only access to objects, for example the credentials holding structures, is also thread-safe.

The random generator of the cryptographic back-end, is not thread safe and requires mutex locks which are setup by GnuTLS. Applications can either call gnutls_global_init which will initialize the default operating system provided locks (i.e. pthreads on GNU/Linux and CriticalSection on Windows), or manually specify the locking system using the function gnutls_global_set_mutex before calling gnutls_global_init. Setting mutexes manually is recommended only for applications that have full control of the underlying libraries. If this is not the case, the use of the operating system defaults is recommended. An example of non-native thread usage is shown below.

#include <gnutls/gnutls.h>

int main()
{
   /* When the system mutexes are not to be used
    * gnutls_global_set_mutex() must be called explicitly
    */
   gnutls_global_set_mutex (mutex_init, mutex_deinit,
                            mutex_lock, mutex_unlock);
   gnutls_global_init();
}

gnutls_global_set_mutex

Callback functions

There are several cases where GnuTLS may need out of band input from your program. This is now implemented using some callback functions, which your program is expected to register.

An example of this type of functions are the push and pull callbacks which are used to specify the functions that will retrieve and send data to the transport layer.

gnutls_transport_set_push_function

gnutls_transport_set_pull_function

Other callback functions may require more complicated input and data to be allocated. Such an example is gnutls_srp_set_server_credentials_function. All callbacks should allocate and free memory using gnutls_malloc and gnutls_free.

[12] The first message in a TLS handshake

Preparation

To use GnuTLS, you have to perform some changes to your sources and your build system. The necessary changes are explained in the following subsections.

Headers

All the data types and functions of the GnuTLS library are defined in the header file gnutls/gnutls.h. This must be included in all programs that make use of the GnuTLS library.

Initialization

GnuTLS must be initialized before it can be used. The library is initialized by calling gnutls_global_init. The resources allocated by the initialization process can be released if the application no longer has a need to call GnuTLS functions, this is done by calling gnutls_global_deinit.

In order to take advantage of the internationalization features in GnuTLS, such as translated error messages, the application must set the current locale using setlocale before initializing GnuTLS.

Version check

It is often desirable to check that the version of ‘gnutls’ used is indeed one which fits all requirements. Even with binary compatibility new features may have been introduced but due to problem with the dynamic linker an old version is actually used. So you may want to check that the version is okay right after program start-up. See the function gnutls_check_version.

Building the source

If you want to compile a source file including the gnutls/gnutls.h header file, you must make sure that the compiler can find it in the directory hierarchy. This is accomplished by adding the path to the directory in which the header file is located to the compilers include file search path (via the -I option).

However, the path to the include file is determined at the time the source is configured. To solve this problem, the library uses the external package pkg-config that knows the path to the include file and other configuration options. The options that need to be added to the compiler invocation at compile time are output by the --cflags option to pkg-config gnutls. The following example shows how it can be used at the command line:

gcc -c foo.c `pkg-config gnutls --cflags`

Adding the output of ‘pkg-config gnutls --cflags’ to the compilers command line will ensure that the compiler can find the gnutls/gnutls.h header file.

A similar problem occurs when linking the program with the library. Again, the compiler has to find the library files. For this to work, the path to the library files has to be added to the library search path (via the -L option). For this, the option --libs to pkg-config gnutls can be used. For convenience, this option also outputs all other options that are required to link the program with the library (for instance, the ‘-ltasn1’ option). The example shows how to link foo.o with the library to a program foo.

gcc -o foo foo.o `pkg-config gnutls --libs`

Of course you can also combine both examples to a single command by specifying both options to pkg-config:

gcc -o foo foo.c `pkg-config gnutls --cflags --libs`

When a program uses the GNU autoconf system, then the following line or similar can be used to detect the presence of GnuTLS.

PKG_CHECK_MODULES([LIBGNUTLS], [gnutls >= 3.0.0])

AC_SUBST([LIBGNUTLS_CFLAGS])
AC_SUBST([LIBGNUTLS_LIBS])

Session initialization

In the previous sections we have discussed the global initialization required for GnuTLS as well as the initialization required for each authentication method’s credentials (see Authentication). In this section we elaborate on the TLS or DTLS session initiation. Each session is initialized using gnutls_init which among others is used to specify the type of the connection (server or client), and the underlying protocol type, i.e., datagram (UDP) or reliable (TCP).

gnutls_init

After the session initialization details on the allowed ciphersuites and protocol versions should be set using the priority functions such as gnutls_priority_set_direct. We elaborate on them in Priority Strings. The credentials used for the key exchange method, such as certificates or usernames and passwords should also be associated with the session current session using gnutls_credentials_set.

gnutls_credentials_set

Associating the credentials

Each authentication method is associated with a key exchange method, and a credentials type. The contents of the credentials is method-dependent, e.g. certificates for certificate authentication and should be initialized and associated with a session (see gnutls_credentials_set). A mapping of the key exchange methods with the credential types is shown in tab:key-exchange-cred.

Authentication method

Key exchange

Client credentials

Server credentials

Certificate

KX_RSA, KX_DHE_RSA, KX_DHE_DSS, KX_ECDHE_RSA, KX_ECDHE_ECDSA, KX_RSA_EXPORT

CRD_CERTIFICATE

CRD_CERTIFICATE

Password and certificate

KX_SRP_RSA, KX_SRP_DSS

CRD_SRP

CRD_CERTIFICATE, CRD_SRP

Password

KX_SRP

CRD_SRP

CRD_SRP

Anonymous

KX_ANON_DH, KX_ANON_ECDH

CRD_ANON

CRD_ANON

Pre-shared key

KX_PSK, KX_DHE_PSK, KX_ECDHE_PSK

CRD_PSK

CRD_PSK

Certificates

Server certificate authentication

When using certificates the server is required to have at least one certificate and private key pair. Clients may not hold such a pair, but a server could require it. In this section we discuss general issues applying to both client and server certificates. The next section will elaborate on issues arising from client authentication only.

gnutls_certificate_allocate_credentials

gnutls_certificate_free_credentials

After the credentials structures are initialized, the certificate and key pair must be loaded. This occurs before any TLS session is initialized, and the same structures are reused for multiple sessions. Depending on the certificate type different loading functions are available, as shown below. For X.509 certificates, the functions will accept and use a certificate chain that leads to a trusted authority. The certificate chain must be ordered in such way that every certificate certifies the one before it. The trusted authority’s certificate need not to be included since the peer should possess it already.

gnutls_certificate_set_x509_key_mem

gnutls_certificate_set_x509_key

gnutls_certificate_set_x509_key_file

gnutls_certificate_set_openpgp_key_mem

gnutls_certificate_set_openpgp_key

gnutls_certificate_set_openpgp_key_file

gnutls_certificate_set_key

If multiple certificates are used with the functions above each client’s request will be served with the certificate that matches the requested name (see Server name indication).

As an alternative to loading from files or buffers, a callback may be used for the server or the client to specify the certificate and the key at the handshake time. In that case a certificate should be selected according the peer’s signature algorithm preferences. To get those preferences use gnutls_sign_algorithm_get_requested. Both functions are shown below.

gnutls_certificate_set_retrieve_function

gnutls_sign_algorithm_get_requested

The functions above do not handle the requested server name automatically. A server would need to check the name requested by the client using gnutls_server_name_get, and serve the appropriate certificate.

In a handshake, the negotiated cipher suite depends on the certificate’s parameters, so some key exchange methods might not be available with all certificates. GnuTLS will disable ciphersuites that are not compatible with the key, or the enabled authentication methods. For example keys marked as sign-only, will not be able to access the plain RSA ciphersuites, that require decryption. It is not recommended to use RSA keys for both signing and encryption. If possible use a different key for the DHE-RSA which uses signing and RSA that requires decryption. All the key exchange methods shown in tab:key-exchange are available in certificate authentication.

Client certificate authentication

If a certificate is to be requested from the client during the handshake, the server will send a certificate request message. This behavior is controlled gnutls_certificate_server_set_request. The request contains a list of the acceptable by the server certificate signers. This list is constructed using the trusted certificate authorities of the server. In cases where the server supports a large number of certificate authorities it makes sense not to advertise all of the names to save bandwidth. That can be controlled using the function gnutls_certificate_send_x509_rdn_sequence. This however will have the side-effect of not restricting the client to certificates signed by server’s acceptable signers.

gnutls_certificate_server_set_request

gnutls_certificate_send_x509_rdn_sequence

Client or server certificate verification

Certificate verification is possible by loading the trusted authorities into the credentials structure by using the following functions, applicable to X.509 and OpenPGP certificates.

gnutls_certificate_set_x509_trust_file

gnutls_certificate_set_openpgp_keyring_file

The peer’s certificate is not automatically verified and one should call gnutls_certificate_verify_peers2 after a successful handshake to verify the certificate’s signature. Alternative the verification can occur during the handshake by using gnutls_certificate_set_verify_function.

In order to report a detailed verification output, an alternative way has to be used. For that, one should call gnutls_certificate_get_peers to obtain the raw certificate of the peer and verify it using the functions discussed in X.509 certificates.

gnutls_certificate_verify_peers2

gnutls_certificate_set_verify_function

SRP

The initialization functions in SRP credentials differ between client and server. Clients supporting SRP should set the username and password prior to connection, to the credentials structure. Alternatively gnutls_srp_set_client_credentials_function may be used instead, to specify a callback function that should return the SRP username and password. The callback is called once during the TLS handshake.

gnutls_srp_allocate_server_credentials

gnutls_srp_allocate_client_credentials

gnutls_srp_free_server_credentials

gnutls_srp_free_client_credentials

gnutls_srp_set_client_credentials

gnutls_srp_set_client_credentials_function

In server side the default behavior of GnuTLS is to read the usernames and SRP verifiers from password files. These password file format is compatible the with the Stanford srp libraries format. If a different password file format is to be used, then gnutls_srp_set_server_credentials_function should be called, to set an appropriate callback.

gnutls_srp_set_server_credentials_file

gnutls_srp_set_server_credentials_function

PSK

The initialization functions in PSK credentials differ between client and server.

gnutls_psk_allocate_server_credentials

gnutls_psk_allocate_client_credentials

gnutls_psk_free_server_credentials

gnutls_psk_free_client_credentials

Clients supporting PSK should supply the username and key before a TLS session is established. Alternatively gnutls_psk_set_client_credentials_function can be used to specify a callback function. This has the advantage that the callback will be called only if PSK has been negotiated.

gnutls_psk_set_client_credentials

gnutls_psk_set_client_credentials_function

In server side the default behavior of GnuTLS is to read the usernames and PSK keys from a password file. The password file should contain usernames and keys in hexadecimal format. The name of the password file can be stored to the credentials structure by calling gnutls_psk_set_server_credentials_file. If a different password file format is to be used, then a callback should be set instead by gnutls_psk_set_server_credentials_function.

The server can help the client chose a suitable username and password, by sending a hint. Note that there is no common profile for the PSK hint and applications are discouraged to use it. A server, may specify the hint by calling gnutls_psk_set_server_credentials_hint. The client can retrieve the hint, for example in the callback function, using gnutls_psk_client_get_hint.

gnutls_psk_set_server_credentials_file

gnutls_psk_set_server_credentials_function

gnutls_psk_set_server_credentials_hint

gnutls_psk_client_get_hint

Anonymous

The key exchange methods for anonymous authentication might require Diffie-Hellman parameters to be generated by the server and associated with an anonymous credentials structure. Check Parameter generation for more information. The initialization functions for the credentials are shown below.

gnutls_anon_allocate_server_credentials

gnutls_anon_allocate_client_credentials

gnutls_anon_free_server_credentials

gnutls_anon_free_client_credentials

Setting up the transport layer

The next step is to setup the underlying transport layer details. The Berkeley sockets are implicitly used by GnuTLS, thus a call to gnutls_transport_set_ptr2 would be sufficient to specify the socket descriptor.

gnutls_transport_set_ptr2

gnutls_transport_set_ptr

If however another transport layer than TCP is selected, then the following functions have to be specified.

gnutls_transport_set_push_function

gnutls_transport_set_vec_push_function

gnutls_transport_set_pull_function

The functions above accept a callback function which should return the number of bytes written, or -1 on error and should set errno appropriately. In some environments, setting errno is unreliable. For example Windows have several errno variables in different CRTs, or in other systems it may be a non thread-local variable. If this is a concern to you, call gnutls_transport_set_errno with the intended errno value instead of setting errno directly.

gnutls_transport_set_errno

GnuTLS currently only interprets the EINTR and EAGAIN errno values and returns the corresponding GnuTLS error codes:

GNUTLS_E_INTERRUPTED

GNUTLS_E_AGAIN

The EINTR and EAGAIN values are returned by interrupted system calls, or when non blocking IO is used. All GnuTLS functions can be resumed (called again), if any of the above error codes is returned.

In the case of DTLS it is also desirable to override the generic transport functions with functions that emulate the operation of recvfrom and sendto. In addition DTLS requires timers during the receive of a handshake message, set using the gnutls_transport_set_pull_timeout_function function. To check the retransmission timers the function gnutls_dtls_get_timeout is provided, which returns the time remaining until the next retransmission, or better the time until gnutls_handshake should be called again.

gnutls_transport_set_pull_timeout_function

gnutls_dtls_get_timeout

Asynchronous operation

GnuTLS can be used with asynchronous socket or event-driven programming. The approach is similar to using Berkeley sockets under such an environment. The blocking, due to network interaction, calls such as gnutls_handshake, gnutls_record_recv, can be set to non-blocking by setting the underlying sockets to non-blocking. If other push and pull functions are setup, then they should behave the same way as recv and send when used in a non-blocking way, i.e., set errno to EAGAIN. Since, during a TLS protocol session GnuTLS does not block except for network interaction, the non blocking EAGAIN errno will be propagated and GnuTLS functions will return the GNUTLS_E_AGAIN error code. Such calls can be resumed the same way as a system call would. The only exception is gnutls_record_send, which if interrupted subsequent calls need not to include the data to be sent (can be called with NULL argument).

The select system call can also be used in combination with the GnuTLS functions. select allows monitoring of sockets and notifies on them being ready for reading or writing data. Note however that this system call cannot notify on data present in GnuTLS read buffers, it is only applicable to the kernel sockets API. Thus if you are using it for reading from a GnuTLS session, make sure that any cached data are read completely. That can be achieved by checking there are no data waiting to be read (using gnutls_record_check_pending), either before the select system call, or after a call to gnutls_record_recv. GnuTLS does not keep a write buffer, thus when writing no additional actions are required.

In the DTLS, however, GnuTLS may block due to retransmission timers required by the protocol. To prevent those timers from blocking a DTLS handshake, the gnutls_init should be called with the GNUTLS_NONBLOCK flag (see Session initialization).

DTLS sessions

Because datagram TLS can operate over connections where the peer of a server cannot be reliably verified, functionality is available to prevent denial of service attacks. GnuTLS requires a server to generate a secret key that is used to sign a cookie[13]. That cookie is sent to the client using gnutls_dtls_cookie_send, and the client must reply using the correct cookie. The server side should verify the initial message sent by client using gnutls_dtls_cookie_verify. If successful the session should be initialized and associated with the cookie using gnutls_dtls_prestate_set, before proceeding to the handshake.

gnutls_key_generate

gnutls_dtls_cookie_send

gnutls_dtls_cookie_verify

gnutls_dtls_prestate_set

Note that the above apply to server side only and they are not mandatory to be used. Not using them, however, allows denial of service attacks. The client side cookie handling is part of gnutls_handshake.

Datagrams are typically restricted by a maximum transfer unit (MTU). For that both client and server side should set the correct maximum transfer unit for the layer underneath GnuTLS. This will allow proper fragmentation of DTLS messages and prevent messages from being silently discarded by the transport layer. The “correct” maximum transfer unit can be obtained through a path MTU discovery mechanism [RFC4821].

gnutls_dtls_set_mtu

gnutls_dtls_get_mtu

gnutls_dtls_get_data_mtu

[13] A key of 128 bits or 16 bytes should be sufficient for this purpose.

TLS handshake

Once a session has been initialized and a network connection has been set up, TLS and DTLS protocols perform a handshake. The handshake is the actual key exchange.

gnutls_handshake

The handshake process doesn’t ensure the verification of the peer’s identity. When certificates are in use, this can be done, either after the handshake is complete, or during the handshake if gnutls_certificate_set_verify_function has been used. In both cases the gnutls_certificate_verify_peers2 function can be used to verify the peer’s certificate (see Certificate authentication for more information).

gnutls_certificate_verify_peers2

Data transfer and termination

Once the handshake is complete and peer’s identity has been verified data can be exchanged. The available functions resemble the POSIX recv and send functions. It is suggested to use gnutls_error_is_fatal to check whether the error codes returned by these functions are fatal for the protocol or can be ignored.

gnutls_record_send

gnutls_record_recv

gnutls_error_is_fatal

Although, in the TLS protocol the receive function can be called at any time, when DTLS is used the GnuTLS receive functions must be called once a message is available for reading, even if no data are expected. This is because in DTLS various (internal) actions may be required due to retransmission timers. Moreover, an extended receive function is shown below, which allows the extraction of the message’s sequence number. Due to the unreliable nature of the protocol, this field allows distinguishing out-of-order messages.

gnutls_record_recv_seq

The gnutls_record_check_pending helper function is available to allow checking whether data are available to be read in a GnuTLS session buffers. Note that this function complements but does not replace select, i.e., gnutls_record_check_pending reports no data to be read, select should be called to check for data in the network buffers.

gnutls_record_check_pending

gnutls_record_get_direction

Once a TLS or DTLS session is no longer needed, it is recommended to use gnutls_bye to terminate the session. That way the peer is notified securely about the intention of termination, which allows distinguishing it from a malicious connection termination. A session can be deinitialized with the gnutls_deinit function.

gnutls_bye

gnutls_deinit

Handling alerts

During a TLS connection alert messages may be exchanged by the two peers. Those messages may be fatal, meaning the connection must be terminated afterwards, or warning when something needs to be reported to the peer, but without interrupting the session. The error codes GNUTLS_E_WARNING_ALERT_RECEIVED or GNUTLS_E_FATAL_ALERT_RECEIVED signal those alerts when received, and may be returned by all GnuTLS functions that receive data from the peer, being gnutls_handshake and gnutls_record_recv. Alerts messages may be sent to the peer using gnutls_alert_send.

gnutls_alert_get

gnutls_alert_send

gnutls_error_to_alert

gnutls_alert_get_name

Priority strings

In order to specify cipher suite preferences on a TLS session there are priority functions that accept a string specifying the enabled for the handshake algorithms. That string may contain a single initial keyword such as in tab:prio-keywords and may be followed by additional algorithm or special keywords.

gnutls_priority_set_direct

gnutls_priority_set

Keyword

Description

PERFORMANCE

All the known to be secure ciphersuites are enabled, limited to 128 bit ciphers and sorted by terms of speed performance. The message authenticity security level is of 64 bits or more.

NORMAL

Means all the known to be secure ciphersuites. The ciphers are sorted by security margin, although the 256-bit ciphers are included as a fallback only. The message authenticity security level is of 64 bits or more.

SECURE128

Means all known to be secure ciphersuites that offer a security level 128-bit or more and a message authenticity security level of 80 bits or more.

SECURE192

Means all the known to be secure ciphersuites that offer a security level 192-bit or more and a message authenticity security level of 128 bits or more.

SECURE256

Currently alias for SECURE192.

SUITEB128

Means all the NSA Suite B cryptography (RFC5430) ciphersuites with an 128 bit security level.

SUITEB192

Means all the NSA Suite B cryptography (RFC5430) ciphersuites with an 192 bit security level.

EXPORT

Means all ciphersuites are enabled, including the low-security 40 bit ciphers.

NONE

Means nothing is enabled. This disables even protocols and compression methods. It should be followed by the algorithms to be enabled.

Unless the initial keyword is "NONE" the defaults (in preference order) are for TLS protocols TLS 1.2, TLS1.1, TLS1.0, SSL3.0; for compression NULL; for certificate types X.509. In key exchange algorithms when in NORMAL or SECURE levels the perfect forward secrecy algorithms take precedence of the other protocols. In all cases all the supported key exchange algorithms are enabled[14].

Note that the SECURE levels distinguish between overall security level and message authenticity security level. That is because the message authenticity security level requires the adversary to break the algorithms at real-time during the protocol run, whilst the overall security level refers to off-line adversaries (e.g. adversaries breaking the ciphertext years after it was captured).

The NONE keyword, if used, must followed by keywords specifying the algorithms and protocols to be enabled. The other initial keywords may be followed by such keywords. The order with which every algorithm or protocol is specified is significant. Algorithms specified before others will take precedence. The supported algorithms and protocols are shown in tab:prio-algorithms. To avoid collisions in order to specify a compression algorithm in the priority string you have to prefix it with "COMP-", protocol versions with "VERS-", signature algorithms with "SIGN-" and certificate types with "CTYPE-". All other algorithms don’t need a prefix. Each specified keyword can be prefixed with any of the following characters.

’!’ or ’-’

appended with an algorithm will remove this algorithm.

"+"

appended with an algorithm will add this algorithm.

Type

Keywords

Ciphers

AES-128-CBC, AES-256-CBC, AES-128-GCM, CAMELLIA-128-CBC, CAMELLIA-256-CBC, ARCFOUR-128, 3DES-CBC ARCFOUR-40. Catch all name is CIPHER-ALL which will add all the algorithms from NORMAL priority.

Key exchange

RSA, DHE-RSA, DHE-DSS, SRP, SRP-RSA, SRP-DSS, PSK, DHE-PSK, ECDHE-RSA, ANON-ECDH, ANON-DH, RSA-EXPORT. The Catch all name is KX-ALL which will add all the algorithms from NORMAL priority.

MAC

MD5, SHA1, SHA256, AEAD (used with GCM ciphers only). All algorithms from NORMAL priority can be accessed with MAC-ALL.

Compression algorithms

COMP-NULL, COMP-DEFLATE. Catch all is COMP-ALL.

TLS versions

VERS-SSL3.0, VERS-TLS1.0, VERS-TLS1.1, VERS-TLS1.2, VERS-DTLS1.0. Catch all is VERS-TLS-ALL.

Signature algorithms

SIGN-RSA-SHA1, SIGN-RSA-SHA224, SIGN-RSA-SHA256, SIGN-RSA-SHA384, SIGN-RSA-SHA512, SIGN-DSA-SHA1, SIGN-DSA-SHA224, SIGN-DSA-SHA256, SIGN-RSA-MD5. Catch all is SIGN-ALL. This is only valid for TLS 1.2 and later.

Elliptic curves

CURVE-SECP192R1, CURVE-SECP224R1, CURVE-SECP256R1, CURVE-SECP384R1, CURVE-SECP521R1. Catch all is CURVE-ALL.

Note that the DHE key exchange methods are generally slower[15] than their elliptic curves counterpart (ECDHE). Moreover the plain Diffie-Hellman key exchange requires parameters to be generated and associated with a credentials structure by the server (see Parameter generation).

The available special keywords are shown in tab:prio-special.

Keyword

Description

%COMPAT

will enable compatibility mode. It might mean that violations of the protocols are allowed as long as maximum compatibility with problematic clients and servers is achieved. More specifically this string would disable TLS record random padding and tolerate packets over the maximum allowed TLS record.

%NO_EXTENSIONS

will prevent the sending of any TLS extensions in client side. Note that TLS 1.2 requires extensions to be used, as well as safe renegotiation thus this option must be used with care.

%SERVER_PRECEDENCE

The ciphersuite will be selected according to server priorities and not the client’s.

%DISABLE_SAFE_RENEGOTIATION

will disable safe renegotiation completely. Do not use unless you know what you are doing. Testing purposes only.

%UNSAFE_RENEGOTIATION

will allow handshakes and re-handshakes without the safe renegotiation extension. Note that for clients this mode is insecure (you may be under attack), and for servers it will allow insecure clients to connect (which could be fooled by an attacker). Do not use unless you know what you are doing and want maximum compatibility.

%PARTIAL_RENEGOTIATION

will allow initial handshakes to proceed, but not re-handshakes. This leaves the client vulnerable to attack, and servers will be compatible with non-upgraded clients for initial handshakes. This is currently the default for clients and servers, for compatibility reasons.

%SAFE_RENEGOTIATION

will enforce safe renegotiation. Clients and servers will refuse to talk to an insecure peer. Currently this causes interoperability problems, but is required for full protection.

%SSL3_RECORD_VERSION

will use SSL3.0 record version in client hello. This is the default.

%LATEST_RECORD_VERSION

will use the latest TLS version record version in client hello.

%VERIFY_ALLOW_SIGN_RSA_MD5

will allow RSA-MD5 signatures in certificate chains.

%VERIFY_ALLOW_X509_V1_CA_CRT

will allow V1 CAs in chains.

Finally the ciphersuites enabled by any priority string can be listed using the gnutls-cli application (see gnutls-cli Invocation), or by using the priority functions as in Listing the ciphersuites in a priority string.

Example priority strings are:

The default priority without the HMAC-MD5:
    "NORMAL:-MD5"

Specifying RSA with AES-128-CBC:
    "NONE:+VERS-TLS-ALL:+MAC-ALL:+RSA:+AES-128-CBC:+SIGN-ALL:+COMP-NULL"

Specifying the defaults except ARCFOUR-128:
    "NORMAL:-ARCFOUR-128"

Enabling the 128-bit secure ciphers, while disabling SSL 3.0 and
enabling compression:
    "SECURE128:-VERS-SSL3.0:+COMP-DEFLATE"

[14] Except for the RSA-EXPORT which is only enabled in EXPORT level.

[15] It depends on the group used. Primes with lesser bits are always faster, but also easier to break. See Selecting cryptographic key sizes for the acceptable security levels.

Advanced and other topics

Session resumption

Client side

To reduce time and roundtrips spent in a handshake the client can request session resumption from a server that previously shared a session with. For that the client has to retrieve and store the session parameters. Before establishing a new session to the same server the parameters must be re-associated with the GnuTLS session using gnutls_session_set_data.

gnutls_session_get_data

gnutls_session_get_id

gnutls_session_set_data

Keep in mind that sessions will be expired after some time, depending on the server, and a server may choose not to resume a session even when requested to. The expiration is to prevent temporal session keys from becoming long-term keys. Also note that as a client you must enable, using the priority functions, at least the algorithms used in the last session.

It is highly recommended for clients to enable the session ticket extension using gnutls_session_ticket_enable_client in order to allow resumption with servers that do not store any state.

gnutls_session_ticket_enable_client

gnutls_session_is_resumed

Server side

In order to support resumption a server can store the session security parameters in a local database or by using session tickets (see Session tickets) to delegate storage to the client. Because session tickets might not be supported by all clients, servers could combine the two methods.

A storing server needs to specify callback functions to store, retrieve and delete session data. These can be registered with the functions below. The stored sessions in the database can be checked using gnutls_db_check_entry for expiration.

gnutls_db_set_retrieve_function

gnutls_db_set_store_function

gnutls_db_set_ptr

gnutls_db_set_remove_function

gnutls_db_check_entry

A server utilizing tickets should generate ticket encryption and authentication keys using gnutls_session_ticket_key_generate. Those keys should be associated with the GnuTLS session using gnutls_session_ticket_enable_server.

gnutls_session_ticket_enable_server

gnutls_session_ticket_key_generate

gnutls_session_resumption_requested

A server enabling both session tickets and a storage for session data would use session tickets when clients support it and the storage otherwise.

Parameter generation

Several TLS ciphersuites require additional parameters that need to be generated or provided by the application. The Diffie-Hellman based ciphersuites (ANON-DH or DHE), require the group parameters to be provided. Those can either be be generated on the fly using gnutls_dh_params_generate2 or imported from pregenerated data using gnutls_dh_params_import_pkcs3. The parameters can be used in a TLS session by calling gnutls_certificate_set_dh_params or gnutls_anon_set_server_dh_params for anonymous sessions.

gnutls_dh_params_generate2

gnutls_dh_params_import_pkcs3

gnutls_certificate_set_dh_params

gnutls_anon_set_server_dh_params

Due to the time-consuming calculations required for the generation of Diffie-Hellman parameters we suggest against performing generation of them within an application. The certtool tool can be used to generate or export known safe values that can be stored in code or in a configuration file to provide the ability to replace. We also recommend the usage of gnutls_sec_param_to_pk_bits (see Selecting cryptographic key sizes) to determine the bit size of the generated parameters.

Note that the information stored in the generated PKCS #3 structure changed with GnuTLS 3.0.9. Since that version the privateValueLength member of the structure is set, allowing the server utilizing the parameters to use keys of the size of the security parameter. This provides better performance in key exchange.

The ciphersuites that involve the RSA-EXPORT key exchange require additional parameters. Those ciphersuites are rarely used today because they are by design insecure, thus if you have no requirement for them, the rest of this section can be skipped. The RSA-EXPORT key exchange requires 512-bit RSA keys to be generated. It is recommended those parameters to be refreshed (regenerated) in short intervals. The following functions can be used for these parameters.

gnutls_rsa_params_generate2

gnutls_certificate_set_rsa_export_params

gnutls_rsa_params_import_pkcs1

gnutls_rsa_params_export_pkcs1

To allow renewal of the parameters within an application without accessing the credentials, which are a shared structure, an alternative interface is available using a callback function.

gnutls_certificate_set_params_function

Keying material exporters

The TLS PRF can be used by other protocols to derive keys based on the TLS master secret. The API to use is gnutls_prf. The function needs to be provided with the label in the parameter label, and the extra data to mix in the extra parameter. Depending on whether you want to mix in the client or server random data first, you can set the server_random_first parameter.

For example, after establishing a TLS session using gnutls_handshake, you can invoke the TLS PRF with this call:

#define MYLABEL "EXPORTER-FOO"
#define MYCONTEXT "some context data"
char out[32];
rc = gnutls_prf (session, strlen (MYLABEL), MYLABEL, 0,
                 strlen (MYCONTEXT), MYCONTEXT, 32, out);

If you don’t want to mix in the client/server random, there is a low-level TLS PRF interface called gnutls_prf_raw.

Channel bindings

In user authentication protocols (e.g., EAP or SASL mechanisms) it is useful to have a unique string that identifies the secure channel that is used, to bind together the user authentication with the secure channel. This can protect against man-in-the-middle attacks in some situations. That unique string is called a “channel binding”. For background and discussion see [RFC5056].

In GnuTLS you can extract a channel binding using the gnutls_session_channel_binding function. Currently only the type GNUTLS_CB_TLS_UNIQUE is supported, which corresponds to the tls-unique channel binding for TLS defined in [RFC5929].

The following example describes how to print the channel binding data. Note that it must be run after a successful TLS handshake.

{
  gnutls_datum_t cb;
  int rc;

  rc = gnutls_session_channel_binding (session,
                                       GNUTLS_CB_TLS_UNIQUE,
                                       &cb);
  if (rc)
    fprintf (stderr, "Channel binding error: %s\n",
             gnutls_strerror (rc));
  else
    {
      size_t i;
      printf ("- Channel binding 'tls-unique': ");
      for (i = 0; i < cb.size; i++)
        printf ("%02x", cb.data[i]);
      printf ("\n");
    }
}

Interoperability

The TLS protocols support many ciphersuites, extensions and version numbers. As a result, few implementations are not able to properly interoperate once faced with extensions or version protocols they do not support and understand. The TLS protocol allows for a graceful downgrade to the commonly supported options, but practice shows it is not always implemented correctly.

Because there is no way to achieve maximum interoperability with broken peers without sacrificing security, GnuTLS ignores such peers by default. This might not be acceptable in cases where maximum compatibility is required. Thus we allow enabling compatibility with broken peers using priority strings (see Priority Strings). A conservative priority string that would disable certain TLS protocol options that are known to cause compatibility problems, is shown below.

NORMAL:%COMPAT

For broken peers that do not tolerate TLS version numbers over TLS 1.0 another priority string is:

NORMAL:-VERS-TLS-ALL:+VERS-TLS1.0:+VERS-SSL3.0:%COMPAT

This priority string will in addition to above, only enable SSL 3.0 and TLS 1.0 as protocols. Note however that there are known attacks against those protocol versions, especially over the CBC-mode ciphersuites. To mitigate them another priority string that only allows the stream cipher ARCFOUR is below.

NORMAL:-VERS-TLS-ALL:+VERS-TLS1.0:+VERS-SSL3.0:-CIPHER-ALL:+ARCFOUR-128:%COMPAT

Compatibility with the OpenSSL library

To ease GnuTLS’ integration with existing applications, a compatibility layer with the OpenSSL library is included in the gnutls-openssl library. This compatibility layer is not complete and it is not intended to completely re-implement the OpenSSL API with GnuTLS. It only provides limited source-level compatibility.

The prototypes for the compatibility functions are in the gnutls/openssl.h header file. The limitations imposed by the compatibility layer include:

Error handling is not thread safe.

Using the cryptographic library

GnuTLS is not a low-level cryptographic library, i.e., it does not provide access to basic cryptographic primitives. However it abstracts the internal cryptographic back-end (see Cryptographic Backend), providing symmetric crypto, hash and HMAC algorithms, as well access to the random number generation.

Symmetric cryptography

The available functions to access symmetric crypto algorithms operations are shown below. The supported algorithms are the algorithms required by the TLS protocol. They are listed in tab:ciphers.

gnutls_cipher_init

gnutls_cipher_encrypt2

gnutls_cipher_decrypt2

gnutls_cipher_set_iv

gnutls_cipher_deinit

In order to support authenticated encryption with associated data (AEAD) algorithms the following functions are provided to set the associated data and retrieve the authentication tag.

gnutls_cipher_add_auth

gnutls_cipher_tag

Hash and HMAC functions

The available operations to access hash functions and hash-MAC (HMAC) algorithms are shown below. HMAC algorithms provided keyed hash functionality. They supported HMAC algorithms are listed in tab:macs.

gnutls_hmac_init

gnutls_hmac

gnutls_hmac_output

gnutls_hmac_deinit

gnutls_hmac_get_len

gnutls_hmac_fast

The available functions to access hash functions are shown below. The supported hash functions are the same as the HMAC algorithms.

gnutls_hash_init

gnutls_hash

gnutls_hash_output

gnutls_hash_deinit

gnutls_hash_get_len

gnutls_hash_fast

Random number generation

Access to the random number generator is provided using the gnutls_rnd function. It allows obtaining random data of various levels.

GNUTLS_RND_NONCE

Non-predictable random number. Fatal in parts of session if broken, i.e., vulnerable to statistical analysis.

GNUTLS_RND_RANDOM

Pseudo-random cryptographic random number. Fatal in session if broken.

GNUTLS_RND_KEY

Fatal in many sessions if broken.

gnutls_rnd

Selecting cryptographic key sizes

Because many algorithms are involved in TLS, it is not easy to set a consistent security level. For this reason in tab:key-sizes we present some correspondence between key sizes of symmetric algorithms and public key algorithms based on [ECRYPT]. Those can be used to generate certificates with appropriate key sizes as well as select parameters for Diffie-Hellman and SRP authentication.

Security bits

RSA, DH and SRP parameter size

ECC key size

Security parameter

Description

80

1248

160

LOW

Very short term protection against agencies

96

1776

192

LEGACY

Legacy standard level

112

2432

224

NORMAL

Medium-term protection

128

3248

256

HIGH

Long term protection

256

15424

512

ULTRA

Foreseeable future

The first column provides a security parameter in a number of bits. This gives an indication of the number of combinations to be tried by an adversary to brute force a key. For example to test all possible keys in a 112 bit security parameter 2^{112} combinations have to be tried. For today’s technology this is infeasible. The next two columns correlate the security parameter with actual bit sizes of parameters for DH, RSA, SRP and ECC algorithms. A mapping to gnutls_sec_param_t value is given for each security parameter, on the next column, and finally a brief description of the level.

Note, however, that the values suggested here are nothing more than an educated guess that is valid today. There are no guarantees that an algorithm will remain unbreakable or that these values will remain constant in time. There could be scientific breakthroughs that cannot be predicted or total failure of the current public key systems by quantum computers. On the other hand though the cryptosystems used in TLS are selected in a conservative way and such catastrophic breakthroughs or failures are believed to be unlikely. The NIST publication SP 800-57 [NISTSP80057] contains a similar table.

When using GnuTLS and a decision on bit sizes for a public key algorithm is required, use of the following functions is recommended:

gnutls_sec_param_to_pk_bits

gnutls_pk_bits_to_sec_param

Those functions will convert a human understandable security parameter of gnutls_sec_param_t type, to a number of bits suitable for a public key algorithm.

Chapter 8. GnuTLS application examples

In this chapter several examples of real-world use cases are listed. The examples are simplified to promote readability and contain little or no error checking.

Client examples

This section contains examples of TLS and SSL clients, using GnuTLS. Note that some of the examples require functions implemented by another example.

Simple client example with anonymous authentication

The simplest client using TLS is the one that doesn’t do any authentication. This means no external certificates or passwords are needed to set up the connection. As could be expected, the connection is vulnerable to man-in-the-middle (active or redirection) attacks. However, the data are integrity protected and encrypted from passive eavesdroppers.

Note that the server must support anonymous authentication as well.

/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <gnutls/gnutls.h>

/* A very basic TLS client, with anonymous authentication.
 */

#define MAX_BUF 1024
#define MSG "GET / HTTP/1.0\r\n\r\n"

extern int tcp_connect (void);
extern void tcp_close (int sd);

int
main (void)
{
  int ret, sd, ii;
  gnutls_session_t session;
  char buffer[MAX_BUF + 1];
  gnutls_anon_client_credentials_t anoncred;
  /* Need to enable anonymous KX specifically. */

  gnutls_global_init ();

  gnutls_anon_allocate_client_credentials (&anoncred);

  /* Initialize TLS session
   */
  gnutls_init (&session, GNUTLS_CLIENT);

  /* Use default priorities */
  gnutls_priority_set_direct (session, "PERFORMANCE:+ANON-ECDH:+ANON-DH",
                              NULL);

  /* put the anonymous credentials to the current session
   */
  gnutls_credentials_set (session, GNUTLS_CRD_ANON, anoncred);

  /* connect to the peer
   */
  sd = tcp_connect ();

  gnutls_transport_set_ptr (session, (gnutls_transport_ptr_t) sd);

  /* Perform the TLS handshake
   */
  do
    {
      ret = gnutls_handshake (session);
    }
  while (ret < 0 && gnutls_error_is_fatal (ret) == 0);

  if (ret < 0)
    {
      fprintf (stderr, "*** Handshake failed\n");
      gnutls_perror (ret);
      goto end;
    }
  else
    {
      printf ("- Handshake was completed\n");
    }

  gnutls_record_send (session, MSG, strlen (MSG));

  ret = gnutls_record_recv (session, buffer, MAX_BUF);
  if (ret == 0)
    {
      printf ("- Peer has closed the TLS connection\n");
      goto end;
    }
  else if (ret < 0)
    {
      fprintf (stderr, "*** Error: %s\n", gnutls_strerror (ret));
      goto end;
    }

  printf ("- Received %d bytes: ", ret);
  for (ii = 0; ii < ret; ii++)
    {
      fputc (buffer[ii], stdout);
    }
  fputs ("\n", stdout);

  gnutls_bye (session, GNUTLS_SHUT_RDWR);

end:

  tcp_close (sd);

  gnutls_deinit (session);

  gnutls_anon_free_client_credentials (anoncred);

  gnutls_global_deinit ();

  return 0;
}

Simple client example with X.509 certificate support

Let’s assume now that we want to create a TCP client which communicates with servers that use X.509 or OpenPGP certificate authentication. The following client is a very simple TLS client, which uses the high level verification functions for certificates, but does not support session resumption.

/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <gnutls/gnutls.h>
#include <gnutls/x509.h>
#include "examples.h"

/* A very basic TLS client, with X.509 authentication and server certificate
 * verification. Note that error checking for missing files etc. is missing
 * for simplicity.
 */

#define MAX_BUF 1024
#define CAFILE "/etc/ssl/certs/ca-certificates.crt"
#define MSG "GET / HTTP/1.0\r\n\r\n"

extern int tcp_connect (void);
extern void tcp_close (int sd);
static int _verify_certificate_callback (gnutls_session_t session);

int main (void)
{
  int ret, sd, ii;
  gnutls_session_t session;
  char buffer[MAX_BUF + 1];
  const char *err;
  gnutls_certificate_credentials_t xcred;

  gnutls_global_init ();

  /* X509 stuff */
  gnutls_certificate_allocate_credentials (&xcred);

  /* sets the trusted cas file
   */
  gnutls_certificate_set_x509_trust_file (xcred, CAFILE, GNUTLS_X509_FMT_PEM);
  gnutls_certificate_set_verify_function (xcred, _verify_certificate_callback);

  /* If client holds a certificate it can be set using the following:
   *
     gnutls_certificate_set_x509_key_file (xcred,
                                           "cert.pem", "key.pem",
                                           GNUTLS_X509_FMT_PEM);
   */

  /* Initialize TLS session
   */
  gnutls_init (&session, GNUTLS_CLIENT);

  gnutls_session_set_ptr (session, (void *) "my_host_name");
  gnutls_server_name_set (session, GNUTLS_NAME_DNS, "my_host_name",
                          strlen("my_host_name"));

  /* Use default priorities */
  ret = gnutls_priority_set_direct (session, "NORMAL", &err);
  if (ret < 0)
    {
      if (ret == GNUTLS_E_INVALID_REQUEST)
        {
          fprintf (stderr, "Syntax error at: %s\n", err);
        }
      exit (1);
    }

  /* put the x509 credentials to the current session
   */
  gnutls_credentials_set (session, GNUTLS_CRD_CERTIFICATE, xcred);

  /* connect to the peer
   */
  sd = tcp_connect ();

  gnutls_transport_set_ptr (session, (gnutls_transport_ptr_t) sd);

  /* Perform the TLS handshake
   */
  do
    {
      ret = gnutls_handshake (session);
    }
  while (ret < 0 && gnutls_error_is_fatal (ret) == 0);

  if (ret < 0)
    {
      fprintf (stderr, "*** Handshake failed\n");
      gnutls_perror (ret);
      goto end;
    }
  else
    {
      printf ("- Handshake was completed\n");
    }

  gnutls_record_send (session, MSG, strlen (MSG));

  ret = gnutls_record_recv (session, buffer, MAX_BUF);
  if (ret == 0)
    {
      printf ("- Peer has closed the TLS connection\n");
      goto end;
    }
  else if (ret < 0)
    {
      fprintf (stderr, "*** Error: %s\n", gnutls_strerror (ret));
      goto end;
    }

  printf ("- Received %d bytes: ", ret);
  for (ii = 0; ii < ret; ii++)
    {
      fputc (buffer[ii], stdout);
    }
  fputs ("\n", stdout);

  gnutls_bye (session, GNUTLS_SHUT_RDWR);

end:

  tcp_close (sd);

  gnutls_deinit (session);

  gnutls_certificate_free_credentials (xcred);

  gnutls_global_deinit ();

  return 0;
}

/* This function will verify the peer's certificate, and check
 * if the hostname matches, as well as the activation, expiration dates.
 */
static int
_verify_certificate_callback (gnutls_session_t session)
{
  unsigned int status;
  const gnutls_datum_t *cert_list;
  unsigned int cert_list_size;
  int ret;
  gnutls_x509_crt_t cert;
  const char *hostname;

  /* read hostname */
  hostname = gnutls_session_get_ptr (session);

  /* This verification function uses the trusted CAs in the credentials
   * structure. So you must have installed one or more CA certificates.
   */
  ret = gnutls_certificate_verify_peers2 (session, &status);
  if (ret < 0)
    {
      printf ("Error\n");
      return GNUTLS_E_CERTIFICATE_ERROR;
    }

  if (status & GNUTLS_CERT_INVALID)
    printf ("The certificate is not trusted.\n");

  if (status & GNUTLS_CERT_SIGNER_NOT_FOUND)
    printf ("The certificate hasn't got a known issuer.\n");

  if (status & GNUTLS_CERT_REVOKED)
    printf ("The certificate has been revoked.\n");

  if (status & GNUTLS_CERT_EXPIRED)
    printf ("The certificate has expired\n");

  if (status & GNUTLS_CERT_NOT_ACTIVATED)
    printf ("The certificate is not yet activated\n");

  /* Up to here the process is the same for X.509 certificates and
   * OpenPGP keys. From now on X.509 certificates are assumed. This can
   * be easily extended to work with openpgp keys as well.
   */
  if (gnutls_certificate_type_get (session) != GNUTLS_CRT_X509)
    return GNUTLS_E_CERTIFICATE_ERROR;

  if (gnutls_x509_crt_init (&cert) < 0)
    {
      printf ("error in initialization\n");
      return GNUTLS_E_CERTIFICATE_ERROR;
    }

  cert_list = gnutls_certificate_get_peers (session, &cert_list_size);
  if (cert_list == NULL)
    {
      printf ("No certificate was found!\n");
      return GNUTLS_E_CERTIFICATE_ERROR;
    }

  /* This is not a real world example, since we only check the first
   * certificate in the given chain.
   */
  if (gnutls_x509_crt_import (cert, &cert_list[0], GNUTLS_X509_FMT_DER) < 0)
    {
      printf ("error parsing certificate\n");
      return GNUTLS_E_CERTIFICATE_ERROR;
    }

  if (!gnutls_x509_crt_check_hostname (cert, hostname))
    {
      printf ("The certificate's owner does not match hostname '%s'\n",
              hostname);
      return GNUTLS_E_CERTIFICATE_ERROR;
    }

  gnutls_x509_crt_deinit (cert);

  /* notify gnutls to continue handshake normally */
  return 0;
}

Simple client example with SSH-style certificate verification

This is an alternative verification function that will use the X.509 certificate authorities for verification, but also assume an trust on first use (SSH-like) authentication system. That is the user is prompted on unknown public keys and known public keys are considered trusted.

/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <gnutls/gnutls.h>
#include <gnutls/x509.h>
#include "examples.h"

/* This function will verify the peer's certificate, check
 * if the hostname matches. In addition it will perform an
 * SSH-style authentication, where ultimately trusted keys
 * are only the keys that have been seen before.
 */
int
_ssh_verify_certificate_callback (gnutls_session_t session)
{
  unsigned int status;
  const gnutls_datum_t *cert_list;
  unsigned int cert_list_size;
  int ret;
  gnutls_x509_crt_t cert;
  const char *hostname;

  /* read hostname */
  hostname = gnutls_session_get_ptr (session);

  /* This verification function uses the trusted CAs in the credentials
   * structure. So you must have installed one or more CA certificates.
   */
  ret = gnutls_certificate_verify_peers2 (session, &status);
  if (ret < 0)
    {
      printf ("Error\n");
      return GNUTLS_E_CERTIFICATE_ERROR;
    }

  if (status & GNUTLS_CERT_INVALID)
    printf ("The certificate is not trusted.\n");

  if (status & GNUTLS_CERT_SIGNER_NOT_FOUND)
    printf ("The certificate hasn't got a known issuer.\n");

  if (status & GNUTLS_CERT_REVOKED)
    printf ("The certificate has been revoked.\n");

  if (status & GNUTLS_CERT_EXPIRED)
    printf ("The certificate has expired\n");

  if (status & GNUTLS_CERT_NOT_ACTIVATED)
    printf ("The certificate is not yet activated\n");

  /* Up to here the process is the same for X.509 certificates and
   * OpenPGP keys. From now on X.509 certificates are assumed. This can
   * be easily extended to work with openpgp keys as well.
   */
  if (gnutls_certificate_type_get (session) != GNUTLS_CRT_X509)
    return GNUTLS_E_CERTIFICATE_ERROR;

  if (gnutls_x509_crt_init (&cert) < 0)
    {
      printf ("error in initialization\n");
      return GNUTLS_E_CERTIFICATE_ERROR;
    }

  cert_list = gnutls_certificate_get_peers (session, &cert_list_size);
  if (cert_list == NULL)
    {
      printf ("No certificate was found!\n");
      return GNUTLS_E_CERTIFICATE_ERROR;
    }

  /* This is not a real world example, since we only check the first
   * certificate in the given chain.
   */
  if (gnutls_x509_crt_import (cert, &cert_list[0], GNUTLS_X509_FMT_DER) < 0)
    {
      printf ("error parsing certificate\n");
      return GNUTLS_E_CERTIFICATE_ERROR;
    }

  if (!gnutls_x509_crt_check_hostname (cert, hostname))
    {
      printf ("The certificate's owner does not match hostname '%s'\n",
              hostname);
      status |= GNUTLS_CERT_INVALID;
    }

  gnutls_x509_crt_deinit (cert);

  /* service may be obtained alternatively using getservbyport() */
  ret = gnutls_verify_stored_pubkey(NULL, NULL, hostname, "https",
                                    GNUTLS_CRT_X509, &cert_list[0], 0);
  if (ret == GNUTLS_E_NO_CERTIFICATE_FOUND)
    {
      printf("Host %s is not known.", hostname);
      if (status == 0)
        printf("Its certificate is valid for %s.\n", hostname);

      /* the certificate must be printed and user must be asked on
       * whether it is trustworthy. --see gnutls_x509_crt_print() */

      /* if not trusted */
      return GNUTLS_E_CERTIFICATE_ERROR;
    }
  else if (ret == GNUTLS_E_CERTIFICATE_KEY_MISMATCH)
    {
      printf("Warning: host %s is known but has another key associated.", hostname);
      printf("It might be that the server has multiple keys, or you are under attack\n");
      if (status == 0)
        printf("Its certificate is valid for %s.\n", hostname);

      /* the certificate must be printed and user must be asked on
       * whether it is trustworthy. --see gnutls_x509_crt_print() */

      /* if not trusted */
      return GNUTLS_E_CERTIFICATE_ERROR;
    }
  else if (ret < 0)
    {
      printf("gnutls_verify_stored_pubkey: %s\n", gnutls_strerror(ret));
      return ret;
    }

  /* user trusts the key -> store it */
  if (ret != 0)
    {
      ret = gnutls_store_pubkey(NULL, NULL, hostname, "https",
                                GNUTLS_CRT_X509, &cert_list[0],
                                0, 0);
      if (ret < 0)
        printf("gnutls_store_pubkey: %s\n", gnutls_strerror(ret));
    }

  /* notify gnutls to continue handshake normally */
  return 0;
}

Simple datagram TLS client example

This is a client that uses UDP to connect to a server. This is the DTLS equivalent to the TLS example with X.509 certificates.

/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <gnutls/gnutls.h>
#include <gnutls/dtls.h>

/* A very basic Datagram TLS client, over UDP with X.509 authentication.
 */

#define MAX_BUF 1024
#define CAFILE "/etc/ssl/certs/ca-certificates.crt"
#define MSG "GET / HTTP/1.0\r\n\r\n"

extern int udp_connect (void);
extern void udp_close (int sd);
extern int verify_certificate_callback (gnutls_session_t session);

int
main (void)
{
  int ret, sd, ii;
  gnutls_session_t session;
  char buffer[MAX_BUF + 1];
  const char *err;
  gnutls_certificate_credentials_t xcred;

  gnutls_global_init ();

  /* X509 stuff */
  gnutls_certificate_allocate_credentials (&xcred);

  /* sets the trusted cas file */
  gnutls_certificate_set_x509_trust_file (xcred, CAFILE, GNUTLS_X509_FMT_PEM);
  gnutls_certificate_set_verify_function (xcred, verify_certificate_callback);

  /* Initialize TLS session */
  gnutls_init (&session, GNUTLS_CLIENT | GNUTLS_DATAGRAM);

  /* Use default priorities */
  ret = gnutls_priority_set_direct (session, "NORMAL", &err);
  if (ret < 0)
    {
      if (ret == GNUTLS_E_INVALID_REQUEST)
        {
          fprintf (stderr, "Syntax error at: %s\n", err);
        }
      exit (1);
    }

  /* put the x509 credentials to the current session */
  gnutls_credentials_set (session, GNUTLS_CRD_CERTIFICATE, xcred);
  gnutls_server_name_set (session, GNUTLS_NAME_DNS, "my_host_name",
                          strlen("my_host_name"));

  /* connect to the peer */
  sd = udp_connect ();

  gnutls_transport_set_ptr (session, (gnutls_transport_ptr_t) sd);

  /* set the connection MTU */
  gnutls_dtls_set_mtu (session, 1000);

  /* Perform the TLS handshake */
  do
    {
      ret = gnutls_handshake (session);
    }
  while (ret < 0 && gnutls_error_is_fatal (ret) == 0);

  if (ret < 0)
    {
      fprintf (stderr, "*** Handshake failed\n");
      gnutls_perror (ret);
      goto end;
    }
  else
    {
      printf ("- Handshake was completed\n");
    }

  gnutls_record_send (session, MSG, strlen (MSG));

  ret = gnutls_record_recv (session, buffer, MAX_BUF);
  if (ret == 0)
    {
      printf ("- Peer has closed the TLS connection\n");
      goto end;
    }
  else if (ret < 0)
    {
      fprintf (stderr, "*** Error: %s\n", gnutls_strerror (ret));
      goto end;
    }

  printf ("- Received %d bytes: ", ret);
  for (ii = 0; ii < ret; ii++)
    {
      fputc (buffer[ii], stdout);
    }
  fputs ("\n", stdout);

  /* It is suggested not to use GNUTLS_SHUT_RDWR in DTLS
   * connections because the peer's closure message might
   * be lost */
  gnutls_bye (session, GNUTLS_SHUT_WR);

end:

  udp_close (sd);

  gnutls_deinit (session);

  gnutls_certificate_free_credentials (xcred);

  gnutls_global_deinit ();

  return 0;
}

Obtaining session information

Most of the times it is desirable to know the security properties of the current established session. This includes the underlying ciphers and the protocols involved. That is the purpose of the following function. Note that this function will print meaningful values only if called after a successful gnutls_handshake.

/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <gnutls/gnutls.h>
#include <gnutls/x509.h>

#include "examples.h"

/* This function will print some details of the
 * given session.
 */
int
print_info (gnutls_session_t session)
{
  const char *tmp;
  gnutls_credentials_type_t cred;
  gnutls_kx_algorithm_t kx;
  int dhe, ecdh;

  dhe = ecdh = 0;

  /* print the key exchange's algorithm name
   */
  kx = gnutls_kx_get (session);
  tmp = gnutls_kx_get_name (kx);
  printf ("- Key Exchange: %s\n", tmp);

  /* Check the authentication type used and switch
   * to the appropriate.
   */
  cred = gnutls_auth_get_type (session);
  switch (cred)
    {
    case GNUTLS_CRD_IA:
      printf ("- TLS/IA session\n");
      break;

#ifdef ENABLE_SRP
    case GNUTLS_CRD_SRP:
      printf ("- SRP session with username %s\n",
              gnutls_srp_server_get_username (session));
      break;
#endif

    case GNUTLS_CRD_PSK:
      /* This returns NULL in server side.
       */
      if (gnutls_psk_client_get_hint (session) != NULL)
        printf ("- PSK authentication. PSK hint '%s'\n",
                gnutls_psk_client_get_hint (session));
      /* This returns NULL in client side.
       */
      if (gnutls_psk_server_get_username (session) != NULL)
        printf ("- PSK authentication. Connected as '%s'\n",
                gnutls_psk_server_get_username (session));

      if (kx == GNUTLS_KX_ECDHE_PSK)
        ecdh = 1;
      else if (kx == GNUTLS_KX_DHE_PSK)
        dhe = 1;
      break;

    case GNUTLS_CRD_ANON:      /* anonymous authentication */

      printf ("- Anonymous authentication.\n");
      if (kx == GNUTLS_KX_ANON_ECDH)
        ecdh = 1;
      else if (kx == GNUTLS_KX_ANON_DH)
        dhe = 1;
      break;

    case GNUTLS_CRD_CERTIFICATE:       /* certificate authentication */

      /* Check if we have been using ephemeral Diffie-Hellman.
       */
      if (kx == GNUTLS_KX_DHE_RSA || kx == GNUTLS_KX_DHE_DSS)
        dhe = 1;
      else if (kx == GNUTLS_KX_ECDHE_RSA || kx == GNUTLS_KX_ECDHE_ECDSA)
        ecdh = 1;

      /* if the certificate list is available, then
       * print some information about it.
       */
      print_x509_certificate_info (session);

    }                           /* switch */

  if (ecdh != 0)
    printf ("- Ephemeral ECDH using curve %s\n",
            gnutls_ecc_curve_get_name (gnutls_ecc_curve_get (session)));
  else if (dhe != 0)
    printf ("- Ephemeral DH using prime of %d bits\n",
            gnutls_dh_get_prime_bits (session));

  /* print the protocol's name (ie TLS 1.0)
   */
  tmp = gnutls_protocol_get_name (gnutls_protocol_get_version (session));
  printf ("- Protocol: %s\n", tmp);

  /* print the certificate type of the peer.
   * ie X.509
   */
  tmp =
    gnutls_certificate_type_get_name (gnutls_certificate_type_get (session));

  printf ("- Certificate Type: %s\n", tmp);

  /* print the compression algorithm (if any)
   */
  tmp = gnutls_compression_get_name (gnutls_compression_get (session));
  printf ("- Compression: %s\n", tmp);

  /* print the name of the cipher used.
   * ie 3DES.
   */
  tmp = gnutls_cipher_get_name (gnutls_cipher_get (session));
  printf ("- Cipher: %s\n", tmp);

  /* Print the MAC algorithms name.
   * ie SHA1
   */
  tmp = gnutls_mac_get_name (gnutls_mac_get (session));
  printf ("- MAC: %s\n", tmp);

  return 0;
}

Using a callback to select the certificate to use

There are cases where a client holds several certificate and key pairs, and may not want to load all of them in the credentials structure. The following example demonstrates the use of the certificate selection callback.

/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <gnutls/gnutls.h>
#include <gnutls/x509.h>
#include <gnutls/abstract.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

/* A TLS client that loads the certificate and key.
 */

#define MAX_BUF 1024
#define MSG "GET / HTTP/1.0\r\n\r\n"

#define CERT_FILE "cert.pem"
#define KEY_FILE "key.pem"
#define CAFILE "/etc/ssl/certs/ca-certificates.crt"

extern int tcp_connect (void);
extern void tcp_close (int sd);

static int
cert_callback (gnutls_session_t session,
               const gnutls_datum_t * req_ca_rdn, int nreqs,
               const gnutls_pk_algorithm_t * sign_algos,
               int sign_algos_length, gnutls_pcert_st ** pcert,
               unsigned int *pcert_length, gnutls_privkey_t * pkey);

gnutls_pcert_st crt;
gnutls_privkey_t key;

/* Helper functions to load a certificate and key
 * files into memory.
 */
static gnutls_datum_t
load_file (const char *file)
{
  FILE *f;
  gnutls_datum_t loaded_file = { NULL, 0 };
  long filelen;
  void *ptr;

  if (!(f = fopen (file, "r"))
      || fseek (f, 0, SEEK_END) != 0
      || (filelen = ftell (f)) < 0
      || fseek (f, 0, SEEK_SET) != 0
      || !(ptr = malloc ((size_t) filelen))
      || fread (ptr, 1, (size_t) filelen, f) < (size_t) filelen)
    {
      if (f)
        fclose (f);
      return loaded_file;
    }

  loaded_file.data = ptr;
  loaded_file.size = (unsigned int) filelen;
  return loaded_file;
}

static void
unload_file (gnutls_datum_t data)
{
  free (data.data);
}

/* Load the certificate and the private key.
 */
static void
load_keys (void)
{
  int ret;
  gnutls_datum_t data;
  gnutls_x509_privkey_t x509_key;

  data = load_file (CERT_FILE);
  if (data.data == NULL)
    {
      fprintf (stderr, "*** Error loading certificate file.\n");
      exit (1);
    }

  ret = gnutls_pcert_import_x509_raw (&crt, &data, GNUTLS_X509_FMT_PEM, 0);
  if (ret < 0)
    {
      fprintf (stderr, "*** Error loading certificate file: %s\n",
               gnutls_strerror (ret));
      exit (1);
    }

  unload_file (data);

  data = load_file (KEY_FILE);
  if (data.data == NULL)
    {
      fprintf (stderr, "*** Error loading key file.\n");
      exit (1);
    }

  gnutls_x509_privkey_init (&x509_key);

  ret = gnutls_x509_privkey_import (x509_key, &data, GNUTLS_X509_FMT_PEM);
  if (ret < 0)
    {
      fprintf (stderr, "*** Error loading key file: %s\n",
               gnutls_strerror (ret));
      exit (1);
    }

  gnutls_privkey_init (&key);

  ret =
    gnutls_privkey_import_x509 (key, x509_key,
                                GNUTLS_PRIVKEY_IMPORT_AUTO_RELEASE);
  if (ret < 0)
    {
      fprintf (stderr, "*** Error importing key: %s\n",
               gnutls_strerror (ret));
      exit (1);
    }

  unload_file (data);
}

int
main (void)
{
  int ret, sd, ii;
  gnutls_session_t session;
  gnutls_priority_t priorities_cache;
  char buffer[MAX_BUF + 1];
  gnutls_certificate_credentials_t xcred;
  /* Allow connections to servers that have OpenPGP keys as well.
   */

  gnutls_global_init ();

  load_keys ();

  /* X509 stuff */
  gnutls_certificate_allocate_credentials (&xcred);

  /* priorities */
  gnutls_priority_init (&priorities_cache, "NORMAL", NULL);

  /* sets the trusted cas file
   */
  gnutls_certificate_set_x509_trust_file (xcred, CAFILE, GNUTLS_X509_FMT_PEM);

  gnutls_certificate_set_retrieve_function2 (xcred, cert_callback);

  /* Initialize TLS session
   */
  gnutls_init (&session, GNUTLS_CLIENT);

  /* Use default priorities */
  gnutls_priority_set (session, priorities_cache);

  /* put the x509 credentials to the current session
   */
  gnutls_credentials_set (session, GNUTLS_CRD_CERTIFICATE, xcred);

  /* connect to the peer
   */
  sd = tcp_connect ();

  gnutls_transport_set_ptr (session, (gnutls_transport_ptr_t) sd);

  /* Perform the TLS handshake
   */
  ret = gnutls_handshake (session);

  if (ret < 0)
    {
      fprintf (stderr, "*** Handshake failed\n");
      gnutls_perror (ret);
      goto end;
    }
  else
    {
      printf ("- Handshake was completed\n");
    }

  gnutls_record_send (session, MSG, strlen (MSG));

  ret = gnutls_record_recv (session, buffer, MAX_BUF);
  if (ret == 0)
    {
      printf ("- Peer has closed the TLS connection\n");
      goto end;
    }
  else if (ret < 0)
    {
      fprintf (stderr, "*** Error: %s\n", gnutls_strerror (ret));
      goto end;
    }

  printf ("- Received %d bytes: ", ret);
  for (ii = 0; ii < ret; ii++)
    {
      fputc (buffer[ii], stdout);
    }
  fputs ("\n", stdout);

  gnutls_bye (session, GNUTLS_SHUT_RDWR);

end:

  tcp_close (sd);

  gnutls_deinit (session);

  gnutls_certificate_free_credentials (xcred);
  gnutls_priority_deinit (priorities_cache);

  gnutls_global_deinit ();

  return 0;
}

/* This callback should be associated with a session by calling
 * gnutls_certificate_client_set_retrieve_function( session, cert_callback),
 * before a handshake.
 */

static int
cert_callback (gnutls_session_t session,
               const gnutls_datum_t * req_ca_rdn, int nreqs,
               const gnutls_pk_algorithm_t * sign_algos,
               int sign_algos_length, gnutls_pcert_st ** pcert,
               unsigned int *pcert_length, gnutls_privkey_t * pkey)
{
  char issuer_dn[256];
  int i, ret;
  size_t len;
  gnutls_certificate_type_t type;

  /* Print the server's trusted CAs
   */
  if (nreqs > 0)
    printf ("- Server's trusted authorities:\n");
  else
    printf ("- Server did not send us any trusted authorities names.\n");

  /* print the names (if any) */
  for (i = 0; i < nreqs; i++)
    {
      len = sizeof (issuer_dn);
      ret = gnutls_x509_rdn_get (&req_ca_rdn[i], issuer_dn, &len);
      if (ret >= 0)
        {
          printf ("   [%d]: ", i);
          printf ("%s\n", issuer_dn);
        }
    }

  /* Select a certificate and return it.
   * The certificate must be of any of the "sign algorithms"
   * supported by the server.
   */
  type = gnutls_certificate_type_get (session);
  if (type == GNUTLS_CRT_X509)
    {
      *pcert_length = 1;
      *pcert = &crt;
      *pkey = key;
    }
  else
    {
      return -1;
    }

  return 0;

}

Verifying a certificate

An example is listed below which uses the high level verification functions to verify a given certificate list.

/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <gnutls/gnutls.h>
#include <gnutls/x509.h>

#include "examples.h"

/* All the available CRLs
 */
gnutls_x509_crl_t *crl_list;
int crl_list_size;

/* All the available trusted CAs
 */
gnutls_x509_crt_t *ca_list;
int ca_list_size;

static int print_details_func (gnutls_x509_crt_t cert,
                               gnutls_x509_crt_t issuer,
                               gnutls_x509_crl_t crl,
                               unsigned int verification_output);

/* This function will try to verify the peer's certificate chain, and
 * also check if the hostname matches.
 */
void
verify_certificate_chain (const char *hostname,
                          const gnutls_datum_t * cert_chain,
                          int cert_chain_length)
{
  int i;
  gnutls_x509_trust_list_t tlist;
  gnutls_x509_crt_t *cert;

  unsigned int output;

  /* Initialize the trusted certificate list. This should be done
   * once on initialization. gnutls_x509_crt_list_import2() and
   * gnutls_x509_crl_list_import2() can be used to load them.
   */
  gnutls_x509_trust_list_init (&tlist, 0);

  gnutls_x509_trust_list_add_cas (tlist, ca_list, ca_list_size, 0);
  gnutls_x509_trust_list_add_crls (tlist, crl_list, crl_list_size,
                                   GNUTLS_TL_VERIFY_CRL, 0);

  cert = malloc (sizeof (*cert) * cert_chain_length);

  /* Import all the certificates in the chain to
   * native certificate format.
   */
  for (i = 0; i < cert_chain_length; i++)
    {
      gnutls_x509_crt_init (&cert[i]);
      gnutls_x509_crt_import (cert[i], &cert_chain[i], GNUTLS_X509_FMT_DER);
    }

  gnutls_x509_trust_list_verify_named_crt (tlist, cert[0], hostname,
                                           strlen (hostname),
                                           GNUTLS_VERIFY_DISABLE_CRL_CHECKS,
                                           &output, print_details_func);

  /* if this certificate is not explicitly trusted verify against CAs
   */
  if (output != 0)
    {
      gnutls_x509_trust_list_verify_crt (tlist, cert, cert_chain_length, 0,
                                         &output, print_details_func);
    }

  if (output & GNUTLS_CERT_INVALID)
    {
      fprintf (stderr, "Not trusted");

      if (output & GNUTLS_CERT_SIGNER_NOT_FOUND)
        fprintf (stderr, ": no issuer was found");
      if (output & GNUTLS_CERT_SIGNER_NOT_CA)
        fprintf (stderr, ": issuer is not a CA");
      if (output & GNUTLS_CERT_NOT_ACTIVATED)
        fprintf (stderr, ": not yet activated\n");
      if (output & GNUTLS_CERT_EXPIRED)
        fprintf (stderr, ": expired\n");

      fprintf (stderr, "\n");
    }
  else
    fprintf (stderr, "Trusted\n");

  /* Check if the name in the first certificate matches our destination!
   */
  if (!gnutls_x509_crt_check_hostname (cert[0], hostname))
    {
      printf ("The certificate's owner does not match hostname '%s'\n",
              hostname);
    }

  gnutls_x509_trust_list_deinit (tlist, 1);

  return;
}

static int
print_details_func (gnutls_x509_crt_t cert,
                    gnutls_x509_crt_t issuer, gnutls_x509_crl_t crl,
                    unsigned int verification_output)
{
  char name[512];
  char issuer_name[512];
  size_t name_size;
  size_t issuer_name_size;

  issuer_name_size = sizeof (issuer_name);
  gnutls_x509_crt_get_issuer_dn (cert, issuer_name, &issuer_name_size);

  name_size = sizeof (name);
  gnutls_x509_crt_get_dn (cert, name, &name_size);

  fprintf (stdout, "\tSubject: %s\n", name);
  fprintf (stdout, "\tIssuer: %s\n", issuer_name);

  if (issuer != NULL)
    {
      issuer_name_size = sizeof (issuer_name);
      gnutls_x509_crt_get_dn (issuer, issuer_name, &issuer_name_size);

      fprintf (stdout, "\tVerified against: %s\n", issuer_name);
    }

  if (crl != NULL)
    {
      issuer_name_size = sizeof (issuer_name);
      gnutls_x509_crl_get_issuer_dn (crl, issuer_name, &issuer_name_size);

      fprintf (stdout, "\tVerified against CRL of: %s\n", issuer_name);
    }

  fprintf (stdout, "\tVerification output: %x\n\n", verification_output);

  return 0;
}

Using a smart card with TLS

This example will demonstrate how to load keys and certificates from a smart-card or any other PKCS #11 token, and use it in a TLS connection.

/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <gnutls/gnutls.h>
#include <gnutls/x509.h>
#include <gnutls/pkcs11.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <getpass.h> /* for getpass() */

/* A TLS client that loads the certificate and key.
 */

#define MAX_BUF 1024
#define MSG "GET / HTTP/1.0\r\n\r\n"
#define MIN(x,y) (((x)<(y))?(x):(y))

#define CAFILE "/etc/ssl/certs/ca-certificates.crt"

/* The URLs of the objects can be obtained
 * using p11tool --list-all --login
 */
#define KEY_URL "pkcs11:manufacturer=SomeManufacturer;object=Private%20Key" \
  ";objecttype=private;id=%db%5b%3e%b5%72%33"
#define CERT_URL "pkcs11:manufacturer=SomeManufacturer;object=Certificate;" \
  "objecttype=cert;id=db%5b%3e%b5%72%33"

extern int tcp_connect (void);
extern void tcp_close (int sd);

static int
pin_callback (void *user, int attempt, const char *token_url,
              const char *token_label, unsigned int flags, char *pin,
              size_t pin_max)
{
  const char *password;
  int len;

  printf ("PIN required for token '%s' with URL '%s'\n", token_label,
          token_url);
  if (flags & GNUTLS_PKCS11_PIN_FINAL_TRY)
    printf ("*** This is the final try before locking!\n");
  if (flags & GNUTLS_PKCS11_PIN_COUNT_LOW)
    printf ("*** Only few tries left before locking!\n");
  if (flags & GNUTLS_PKCS11_PIN_WRONG)
    printf ("*** Wrong PIN\n");

  password = getpass ("Enter pin: ");
  if (password == NULL || password[0] == 0)
    {
      fprintf (stderr, "No password given\n");
      exit (1);
    }

  len = MIN (pin_max, strlen (password));
  memcpy (pin, password, len);
  pin[len] = 0;

  return 0;
}

int
main (void)
{
  int ret, sd, ii;
  gnutls_session_t session;
  gnutls_priority_t priorities_cache;
  char buffer[MAX_BUF + 1];
  gnutls_certificate_credentials_t xcred;
  /* Allow connections to servers that have OpenPGP keys as well.
   */

  gnutls_global_init ();
  /* PKCS11 private key operations might require PIN.
   * Register a callback.
   */
  gnutls_pkcs11_set_pin_function (pin_callback, NULL);

  /* X509 stuff */
  gnutls_certificate_allocate_credentials (&xcred);

  /* priorities */
  gnutls_priority_init (&priorities_cache, "NORMAL", NULL);

  /* sets the trusted cas file
   */
  gnutls_certificate_set_x509_trust_file (xcred, CAFILE, GNUTLS_X509_FMT_PEM);

  gnutls_certificate_set_x509_key_file (xcred, CERT_URL, KEY_URL, GNUTLS_X509_FMT_DER);

  /* Initialize TLS session
   */
  gnutls_init (&session, GNUTLS_CLIENT);

  /* Use default priorities */
  gnutls_priority_set (session, priorities_cache);

  /* put the x509 credentials to the current session
   */
  gnutls_credentials_set (session, GNUTLS_CRD_CERTIFICATE, xcred);

  /* connect to the peer
   */
  sd = tcp_connect ();

  gnutls_transport_set_ptr (session, (gnutls_transport_ptr_t) sd);

  /* Perform the TLS handshake
   */
  ret = gnutls_handshake (session);

  if (ret < 0)
    {
      fprintf (stderr, "*** Handshake failed\n");
      gnutls_perror (ret);
      goto end;
    }
  else
    {
      printf ("- Handshake was completed\n");
    }

  gnutls_record_send (session, MSG, strlen (MSG));

  ret = gnutls_record_recv (session, buffer, MAX_BUF);
  if (ret == 0)
    {
      printf ("- Peer has closed the TLS connection\n");
      goto end;
    }
  else if (ret < 0)
    {
      fprintf (stderr, "*** Error: %s\n", gnutls_strerror (ret));
      goto end;
    }

  printf ("- Received %d bytes: ", ret);
  for (ii = 0; ii < ret; ii++)
    {
      fputc (buffer[ii], stdout);
    }
  fputs ("\n", stdout);

  gnutls_bye (session, GNUTLS_SHUT_RDWR);

end:

  tcp_close (sd);

  gnutls_deinit (session);

  gnutls_certificate_free_credentials (xcred);
  gnutls_priority_deinit (priorities_cache);

  gnutls_global_deinit ();

  return 0;
}

Client with resume capability example

This is a modification of the simple client example. Here we demonstrate the use of session resumption. The client tries to connect once using TLS, close the connection and then try to establish a new connection using the previously negotiated data.

/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <gnutls/gnutls.h>

/* Those functions are defined in other examples.
 */
extern void check_alert (gnutls_session_t session, int ret);
extern int tcp_connect (void);
extern void tcp_close (int sd);

#define MAX_BUF 1024
#define CAFILE "/etc/ssl/certs/ca-certificates.crt"
#define MSG "GET / HTTP/1.0\r\n\r\n"

int
main (void)
{
  int ret;
  int sd, ii;
  gnutls_session_t session;
  char buffer[MAX_BUF + 1];
  gnutls_certificate_credentials_t xcred;

  /* variables used in session resuming
   */
  int t;
  char *session_data = NULL;
  size_t session_data_size = 0;

  gnutls_global_init ();

  /* X509 stuff */
  gnutls_certificate_allocate_credentials (&xcred);

  gnutls_certificate_set_x509_trust_file (xcred, CAFILE, GNUTLS_X509_FMT_PEM);

  for (t = 0; t < 2; t++)
    {                           /* connect 2 times to the server */

      sd = tcp_connect ();

      gnutls_init (&session, GNUTLS_CLIENT);

      gnutls_priority_set_direct (session, "PERFORMANCE:!ARCFOUR-128", NULL);

      gnutls_credentials_set (session, GNUTLS_CRD_CERTIFICATE, xcred);

      if (t > 0)
        {
          /* if this is not the first time we connect */
          gnutls_session_set_data (session, session_data, session_data_size);
          free (session_data);
        }

      gnutls_transport_set_ptr (session, (gnutls_transport_ptr_t) sd);

      /* Perform the TLS handshake
       */
      do
        {
          ret = gnutls_handshake (session);
        }
      while (ret < 0 && gnutls_error_is_fatal (ret) == 0);

      if (ret < 0)
        {
          fprintf (stderr, "*** Handshake failed\n");
          gnutls_perror (ret);
          goto end;
        }
      else
        {
          printf ("- Handshake was completed\n");
        }

      if (t == 0)
        {                       /* the first time we connect */
          /* get the session data size */
          gnutls_session_get_data (session, NULL, &session_data_size);
          session_data = malloc (session_data_size);

          /* put session data to the session variable */
          gnutls_session_get_data (session, session_data, &session_data_size);

        }
      else
        {                       /* the second time we connect */

          /* check if we actually resumed the previous session */
          if (gnutls_session_is_resumed (session) != 0)
            {
              printf ("- Previous session was resumed\n");
            }
          else
            {
              fprintf (stderr, "*** Previous session was NOT resumed\n");
            }
        }

      /* This function was defined in a previous example
       */
      /* print_info(session); */

      gnutls_record_send (session, MSG, strlen (MSG));

      ret = gnutls_record_recv (session, buffer, MAX_BUF);
      if (ret == 0)
        {
          printf ("- Peer has closed the TLS connection\n");
          goto end;
        }
      else if (ret < 0)
        {
          fprintf (stderr, "*** Error: %s\n", gnutls_strerror (ret));
          goto end;
        }

      printf ("- Received %d bytes: ", ret);
      for (ii = 0; ii < ret; ii++)
        {
          fputc (buffer[ii], stdout);
        }
      fputs ("\n", stdout);

      gnutls_bye (session, GNUTLS_SHUT_RDWR);

    end:

      tcp_close (sd);

      gnutls_deinit (session);

    }                           /* for() */

  gnutls_certificate_free_credentials (xcred);

  gnutls_global_deinit ();

  return 0;
}

Simple client example with SRP authentication

The following client is a very simple SRP TLS client which connects to a server and authenticates using a username and a password. The server may authenticate itself using a certificate, and in that case it has to be verified.

/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <gnutls/gnutls.h>

/* Those functions are defined in other examples.
 */
extern void check_alert (gnutls_session_t session, int ret);
extern int tcp_connect (void);
extern void tcp_close (int sd);

#define MAX_BUF 1024
#define USERNAME "user"
#define PASSWORD "pass"
#define CAFILE "/etc/ssl/certs/ca-certificates.crt"
#define MSG "GET / HTTP/1.0\r\n\r\n"

int
main (void)
{
  int ret;
  int sd, ii;
  gnutls_session_t session;
  char buffer[MAX_BUF + 1];
  gnutls_srp_client_credentials_t srp_cred;
  gnutls_certificate_credentials_t cert_cred;

  gnutls_global_init ();

  gnutls_srp_allocate_client_credentials (&srp_cred);
  gnutls_certificate_allocate_credentials (&cert_cred);

  gnutls_certificate_set_x509_trust_file (cert_cred, CAFILE,
                                          GNUTLS_X509_FMT_PEM);
  gnutls_srp_set_client_credentials (srp_cred, USERNAME, PASSWORD);

  /* connects to server
   */
  sd = tcp_connect ();

  /* Initialize TLS session
   */
  gnutls_init (&session, GNUTLS_CLIENT);

  /* Set the priorities.
   */
  gnutls_priority_set_direct (session, "NORMAL:+SRP:+SRP-RSA:+SRP-DSS", NULL);

  /* put the SRP credentials to the current session
   */
  gnutls_credentials_set (session, GNUTLS_CRD_SRP, srp_cred);
  gnutls_credentials_set (session, GNUTLS_CRD_CERTIFICATE, cert_cred);

  gnutls_transport_set_ptr (session, (gnutls_transport_ptr_t) sd);

  /* Perform the TLS handshake
   */
  do
    {
      ret = gnutls_handshake (session);
    }
  while (ret < 0 && gnutls_error_is_fatal (ret) == 0);

  if (ret < 0)
    {
      fprintf (stderr, "*** Handshake failed\n");
      gnutls_perror (ret);
      goto end;
    }
  else
    {
      printf ("- Handshake was completed\n");
    }

  gnutls_record_send (session, MSG, strlen (MSG));

  ret = gnutls_record_recv (session, buffer, MAX_BUF);
  if (gnutls_error_is_fatal (ret) != 0 || ret == 0)
    {
      if (ret == 0)
        {
          printf ("- Peer has closed the GnuTLS connection\n");
          goto end;
        }
      else
        {
          fprintf (stderr, "*** Error: %s\n", gnutls_strerror (ret));
          goto end;
        }
    }
  else
    check_alert (session, ret);

  if (ret > 0)
    {
      printf ("- Received %d bytes: ", ret);
      for (ii = 0; ii < ret; ii++)
        {
          fputc (buffer[ii], stdout);
        }
      fputs ("\n", stdout);
    }
  gnutls_bye (session, GNUTLS_SHUT_RDWR);

end:

  tcp_close (sd);

  gnutls_deinit (session);

  gnutls_srp_free_client_credentials (srp_cred);
  gnutls_certificate_free_credentials (cert_cred);

  gnutls_global_deinit ();

  return 0;
}

Simple client example using the C++ API

The following client is a simple example of a client client utilizing the GnuTLS C++ API.

#include <config.h>
#include <iostream>
#include <stdexcept>
#include <gnutls/gnutls.h>
#include <gnutls/gnutlsxx.h>
#include <cstring> /* for strlen */

/* A very basic TLS client, with anonymous authentication.
 * written by Eduardo Villanueva Che.
 */

#define MAX_BUF 1024
#define SA struct sockaddr

#define CAFILE "ca.pem"
#define MSG "GET / HTTP/1.0\r\n\r\n"

extern "C"
{
    int tcp_connect(void);
    void tcp_close(int sd);
}

int main(void)
{
    int sd = -1;
    gnutls_global_init();

    try
    {

        /* Allow connections to servers that have OpenPGP keys as well.
         */
        gnutls::client_session session;

        /* X509 stuff */
        gnutls::certificate_credentials credentials;

        /* sets the trusted cas file
         */
        credentials.set_x509_trust_file(CAFILE, GNUTLS_X509_FMT_PEM);
        /* put the x509 credentials to the current session
         */
        session.set_credentials(credentials);

        /* Use default priorities */
        session.set_priority ("NORMAL", NULL);

        /* connect to the peer
         */
        sd = tcp_connect();
        session.set_transport_ptr((gnutls_transport_ptr_t) (ptrdiff_t)sd);

        /* Perform the TLS handshake
         */
        int ret = session.handshake();
        if (ret < 0)
        {
            throw std::runtime_error("Handshake failed");
        }
        else
        {
            std::cout << "- Handshake was completed" << std::endl;
        }

        session.send(MSG, strlen(MSG));
        char buffer[MAX_BUF + 1];
        ret = session.recv(buffer, MAX_BUF);
        if (ret == 0)
        {
            throw std::runtime_error("Peer has closed the TLS connection");
        }
        else if (ret < 0)
        {
            throw std::runtime_error(gnutls_strerror(ret));
        }

        std::cout << "- Received " << ret << " bytes:" << std::endl;
        std::cout.write(buffer, ret);
        std::cout << std::endl;

        session.bye(GNUTLS_SHUT_RDWR);
    }
    catch (std::exception &ex)
    {
        std::cerr << "Exception caught: " << ex.what() << std::endl;
    }

    if (sd != -1)
        tcp_close(sd);

    gnutls_global_deinit();

    return 0;
}

Helper functions for TCP connections

Those helper function abstract away TCP connection handling from the other examples. It is required to build some examples.

/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <unistd.h>

/* tcp.c */
int tcp_connect (void);
void tcp_close (int sd);

/* Connects to the peer and returns a socket
 * descriptor.
 */
extern int
tcp_connect (void)
{
  const char *PORT = "5556";
  const char *SERVER = "127.0.0.1";
  int err, sd;
  struct sockaddr_in sa;

  /* connects to server
   */
  sd = socket (AF_INET, SOCK_STREAM, 0);

  memset (&sa, '\0', sizeof (sa));
  sa.sin_family = AF_INET;
  sa.sin_port = htons (atoi (PORT));
  inet_pton (AF_INET, SERVER, &sa.sin_addr);

  err = connect (sd, (struct sockaddr *) & sa, sizeof (sa));
  if (err < 0)
    {
      fprintf (stderr, "Connect error\n");
      exit (1);
    }

  return sd;
}

/* closes the given socket descriptor.
 */
extern void
tcp_close (int sd)
{
  shutdown (sd, SHUT_RDWR);     /* no more receptions */
  close (sd);
}

Helper functions for UDP connections

The UDP helper functions abstract away UDP connection handling from the other examples. It is required to build the examples using UDP.

/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <unistd.h>

/* udp.c */
int udp_connect (void);
void udp_close (int sd);

/* Connects to the peer and returns a socket
 * descriptor.
 */
extern int
udp_connect (void)
{
  const char *PORT = "5557";
  const char *SERVER = "127.0.0.1";
  int err, sd, optval;
  struct sockaddr_in sa;

  /* connects to server
   */
  sd = socket (AF_INET, SOCK_DGRAM, 0);

  memset (&sa, '\0', sizeof (sa));
  sa.sin_family = AF_INET;
  sa.sin_port = htons (atoi (PORT));
  inet_pton (AF_INET, SERVER, &sa.sin_addr);

#if defined(IP_DONTFRAG)
  optval = 1;
  setsockopt (sd, IPPROTO_IP, IP_DONTFRAG,
              (const void *) &optval, sizeof (optval));
#elif defined(IP_MTU_DISCOVER)
  optval = IP_PMTUDISC_DO;
  setsockopt(sd, IPPROTO_IP, IP_MTU_DISCOVER,
             (const void*) &optval, sizeof (optval));
#endif

  err = connect (sd, (struct sockaddr *) & sa, sizeof (sa));
  if (err < 0)
    {
      fprintf (stderr, "Connect error\n");
      exit (1);
    }

  return sd;
}

/* closes the given socket descriptor.
 */
extern void
udp_close (int sd)
{
  close (sd);
}

Server examples

This section contains examples of TLS and SSL servers, using GnuTLS.

Echo server with X.509 authentication

This example is a very simple echo server which supports X.509 authentication.

/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <string.h>
#include <unistd.h>
#include <gnutls/gnutls.h>

#define KEYFILE "key.pem"
#define CERTFILE "cert.pem"
#define CAFILE "/etc/ssl/certs/ca-certificates.crt"
#define CRLFILE "crl.pem"

/* This is a sample TLS 1.0 echo server, using X.509 authentication.
 */

#define MAX_BUF 1024
#define PORT 5556               /* listen to 5556 port */

/* These are global */
gnutls_certificate_credentials_t x509_cred;
gnutls_priority_t priority_cache;

static gnutls_session_t
initialize_tls_session (void)
{
  gnutls_session_t session;

  gnutls_init (&session, GNUTLS_SERVER);

  gnutls_priority_set (session, priority_cache);

  gnutls_credentials_set (session, GNUTLS_CRD_CERTIFICATE, x509_cred);

  /* We don't request any certificate from the client.
   * If we did we would need to verify it.
   */
  gnutls_certificate_server_set_request (session, GNUTLS_CERT_IGNORE);

  return session;
}

static gnutls_dh_params_t dh_params;

static int
generate_dh_params (void)
{
  int bits = gnutls_sec_param_to_pk_bits (GNUTLS_PK_DH, GNUTLS_SEC_PARAM_LOW);

  /* Generate Diffie-Hellman parameters - for use with DHE
   * kx algorithms. When short bit length is used, it might
   * be wise to regenerate parameters often.
   */
  gnutls_dh_params_init (&dh_params);
  gnutls_dh_params_generate2 (dh_params, bits);

  return 0;
}

int
main (void)
{
  int listen_sd;
  int sd, ret;
  struct sockaddr_in sa_serv;
  struct sockaddr_in sa_cli;
  socklen_t client_len;
  char topbuf[512];
  gnutls_session_t session;
  char buffer[MAX_BUF + 1];
  int optval = 1;

  /* this must be called once in the program
   */
  gnutls_global_init ();

  gnutls_certificate_allocate_credentials (&x509_cred);
  gnutls_certificate_set_x509_trust_file (x509_cred, CAFILE,
                                          GNUTLS_X509_FMT_PEM);

  gnutls_certificate_set_x509_crl_file (x509_cred, CRLFILE,
                                        GNUTLS_X509_FMT_PEM);

  ret = gnutls_certificate_set_x509_key_file (x509_cred, CERTFILE, KEYFILE,
                                        GNUTLS_X509_FMT_PEM);
  if (ret < 0)
    {
      printf("No certificate or key were found\n");
      exit(1);
    }

  generate_dh_params ();

  gnutls_priority_init (&priority_cache, "PERFORMANCE:%SERVER_PRECEDENCE", NULL);

  gnutls_certificate_set_dh_params (x509_cred, dh_params);

  /* Socket operations
   */
  listen_sd = socket (AF_INET, SOCK_STREAM, 0);

  memset (&sa_serv, '\0', sizeof (sa_serv));
  sa_serv.sin_family = AF_INET;
  sa_serv.sin_addr.s_addr = INADDR_ANY;
  sa_serv.sin_port = htons (PORT);      /* Server Port number */

  setsockopt (listen_sd, SOL_SOCKET, SO_REUSEADDR, (void *) &optval,
              sizeof (int));

  bind (listen_sd, (struct sockaddr *) & sa_serv, sizeof (sa_serv));

  listen (listen_sd, 1024);

  printf ("Server ready. Listening to port '%d'.\n\n", PORT);

  client_len = sizeof (sa_cli);
  for (;;)
    {
      session = initialize_tls_session ();

      sd = accept (listen_sd, (struct sockaddr *) & sa_cli, &client_len);

      printf ("- connection from %s, port %d\n",
              inet_ntop (AF_INET, &sa_cli.sin_addr, topbuf,
                         sizeof (topbuf)), ntohs (sa_cli.sin_port));

      gnutls_transport_set_ptr (session, (gnutls_transport_ptr_t) sd);

      do
        {
          ret = gnutls_handshake (session);
        }
      while (ret < 0 && gnutls_error_is_fatal (ret) == 0);

      if (ret < 0)
        {
          close (sd);
          gnutls_deinit (session);
          fprintf (stderr, "*** Handshake has failed (%s)\n\n",
                   gnutls_strerror (ret));
          continue;
        }
      printf ("- Handshake was completed\n");

      /* see the Getting peer's information example */
      /* print_info(session); */

      for (;;)
        {
          memset (buffer, 0, MAX_BUF + 1);
          ret = gnutls_record_recv (session, buffer, MAX_BUF);

          if (ret == 0)
            {
              printf ("\n- Peer has closed the GnuTLS connection\n");
              break;
            }
          else if (ret < 0)
            {
              fprintf (stderr, "\n*** Received corrupted "
                       "data(%d). Closing the connection.\n\n", ret);
              break;
            }
          else if (ret > 0)
            {
              /* echo data back to the client
               */
              gnutls_record_send (session, buffer, strlen (buffer));
            }
        }
      printf ("\n");
      /* do not wait for the peer to close the connection.
       */
      gnutls_bye (session, GNUTLS_SHUT_WR);

      close (sd);
      gnutls_deinit (session);

    }
  close (listen_sd);

  gnutls_certificate_free_credentials (x509_cred);
  gnutls_priority_deinit (priority_cache);

  gnutls_global_deinit ();

  return 0;

}

Echo server with OpenPGP authentication

The following example is an echo server which supports OpenPGP key authentication. You can easily combine this functionality —that is have a server that supports both X.509 and OpenPGP certificates— but we separated them to keep these examples as simple as possible.

/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <string.h>
#include <unistd.h>
#include <gnutls/gnutls.h>
#include <gnutls/openpgp.h>

#define KEYFILE "secret.asc"
#define CERTFILE "public.asc"
#define RINGFILE "ring.gpg"

/* This is a sample TLS 1.0-OpenPGP echo server.
 */

#define SOCKET_ERR(err,s) if(err==-1) {perror(s);return(1);}
#define MAX_BUF 1024
#define PORT 5556               /* listen to 5556 port */
#define DH_BITS 1024

/* These are global */
gnutls_certificate_credentials_t cred;
gnutls_dh_params_t dh_params;

static int
generate_dh_params (void)
{

  /* Generate Diffie-Hellman parameters - for use with DHE
   * kx algorithms. These should be discarded and regenerated
   * once a day, once a week or once a month. Depending on the
   * security requirements.
   */
  gnutls_dh_params_init (&dh_params);
  gnutls_dh_params_generate2 (dh_params, DH_BITS);

  return 0;
}

static gnutls_session_t
initialize_tls_session (void)
{
  gnutls_session_t session;

  gnutls_init (&session, GNUTLS_SERVER);

  gnutls_priority_set_direct (session, "NORMAL:+CTYPE-OPENPGP", NULL);

  /* request client certificate if any.
   */
  gnutls_certificate_server_set_request (session, GNUTLS_CERT_REQUEST);

  gnutls_dh_set_prime_bits (session, DH_BITS);

  return session;
}

int
main (void)
{
  int err, listen_sd;
  int sd, ret;
  struct sockaddr_in sa_serv;
  struct sockaddr_in sa_cli;
  socklen_t client_len;
  char topbuf[512];
  gnutls_session_t session;
  char buffer[MAX_BUF + 1];
  int optval = 1;
  char name[256];

  strcpy (name, "Echo Server");

  /* this must be called once in the program
   */
  gnutls_global_init ();

  gnutls_certificate_allocate_credentials (&cred);
  gnutls_certificate_set_openpgp_keyring_file (cred, RINGFILE,
                                               GNUTLS_OPENPGP_FMT_BASE64);

  gnutls_certificate_set_openpgp_key_file (cred, CERTFILE, KEYFILE,
                                           GNUTLS_OPENPGP_FMT_BASE64);

  generate_dh_params ();

  gnutls_certificate_set_dh_params (cred, dh_params);

  /* Socket operations
   */
  listen_sd = socket (AF_INET, SOCK_STREAM, 0);
  SOCKET_ERR (listen_sd, "socket");

  memset (&sa_serv, '\0', sizeof (sa_serv));
  sa_serv.sin_family = AF_INET;
  sa_serv.sin_addr.s_addr = INADDR_ANY;
  sa_serv.sin_port = htons (PORT);      /* Server Port number */

  setsockopt (listen_sd, SOL_SOCKET, SO_REUSEADDR, (void *) &optval,
              sizeof (int));

  err = bind (listen_sd, (struct sockaddr *) & sa_serv, sizeof (sa_serv));
  SOCKET_ERR (err, "bind");
  err = listen (listen_sd, 1024);
  SOCKET_ERR (err, "listen");

  printf ("%s ready. Listening to port '%d'.\n\n", name, PORT);

  client_len = sizeof (sa_cli);
  for (;;)
    {
      session = initialize_tls_session ();

      sd = accept (listen_sd, (struct sockaddr *) & sa_cli, &client_len);

      printf ("- connection from %s, port %d\n",
              inet_ntop (AF_INET, &sa_cli.sin_addr, topbuf,
                         sizeof (topbuf)), ntohs (sa_cli.sin_port));

      gnutls_transport_set_ptr (session, (gnutls_transport_ptr_t) sd);
      ret = gnutls_handshake (session);
      if (ret < 0)
        {
          close (sd);
          gnutls_deinit (session);
          fprintf (stderr, "*** Handshake has failed (%s)\n\n",
                   gnutls_strerror (ret));
          continue;
        }
      printf ("- Handshake was completed\n");

      /* see the Getting peer's information example */
      /* print_info(session); */

      for (;;)
        {
          memset (buffer, 0, MAX_BUF + 1);
          ret = gnutls_record_recv (session, buffer, MAX_BUF);

          if (ret == 0)
            {
              printf ("\n- Peer has closed the GnuTLS connection\n");
              break;
            }
          else if (ret < 0)
            {
              fprintf (stderr, "\n*** Received corrupted "
                       "data(%d). Closing the connection.\n\n", ret);
              break;
            }
          else if (ret > 0)
            {
              /* echo data back to the client
               */
              gnutls_record_send (session, buffer, strlen (buffer));
            }
        }
      printf ("\n");
      /* do not wait for the peer to close the connection.
       */
      gnutls_bye (session, GNUTLS_SHUT_WR);

      close (sd);
      gnutls_deinit (session);

    }
  close (listen_sd);

  gnutls_certificate_free_credentials (cred);

  gnutls_global_deinit ();

  return 0;

}

Echo server with SRP authentication

This is a server which supports SRP authentication. It is also possible to combine this functionality with a certificate server. Here it is separate for simplicity.

/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <string.h>
#include <unistd.h>
#include <gnutls/gnutls.h>

#define SRP_PASSWD "tpasswd"
#define SRP_PASSWD_CONF "tpasswd.conf"

#define KEYFILE "key.pem"
#define CERTFILE "cert.pem"
#define CAFILE "/etc/ssl/certs/ca-certificates.crt"

/* This is a sample TLS-SRP echo server.
 */

#define SOCKET_ERR(err,s) if(err==-1) {perror(s);return(1);}
#define MAX_BUF 1024
#define PORT 5556               /* listen to 5556 port */

/* These are global */
gnutls_srp_server_credentials_t srp_cred;
gnutls_certificate_credentials_t cert_cred;

static gnutls_session_t
initialize_tls_session (void)
{
  gnutls_session_t session;

  gnutls_init (&session, GNUTLS_SERVER);

  gnutls_priority_set_direct (session, "NORMAL:-KX-ALL:+SRP:+SRP-DSS:+SRP-RSA", NULL);

  gnutls_credentials_set (session, GNUTLS_CRD_SRP, srp_cred);
  /* for the certificate authenticated ciphersuites.
   */
  gnutls_credentials_set (session, GNUTLS_CRD_CERTIFICATE, cert_cred);

  /* request client certificate if any.
   */
  gnutls_certificate_server_set_request (session, GNUTLS_CERT_IGNORE);

  return session;
}

int
main (void)
{
  int err, listen_sd;
  int sd, ret;
  struct sockaddr_in sa_serv;
  struct sockaddr_in sa_cli;
  socklen_t client_len;
  char topbuf[512];
  gnutls_session_t session;
  char buffer[MAX_BUF + 1];
  int optval = 1;
  char name[256];

  strcpy (name, "Echo Server");

  gnutls_global_init ();

  /* SRP_PASSWD a password file (created with the included srptool utility)
   */
  gnutls_srp_allocate_server_credentials (&srp_cred);
  gnutls_srp_set_server_credentials_file (srp_cred, SRP_PASSWD,
                                          SRP_PASSWD_CONF);

  gnutls_certificate_allocate_credentials (&cert_cred);
  gnutls_certificate_set_x509_trust_file (cert_cred, CAFILE,
                                          GNUTLS_X509_FMT_PEM);
  gnutls_certificate_set_x509_key_file (cert_cred, CERTFILE, KEYFILE,
                                        GNUTLS_X509_FMT_PEM);

  /* TCP socket operations
   */
  listen_sd = socket (AF_INET, SOCK_STREAM, 0);
  SOCKET_ERR (listen_sd, "socket");

  memset (&sa_serv, '\0', sizeof (sa_serv));
  sa_serv.sin_family = AF_INET;
  sa_serv.sin_addr.s_addr = INADDR_ANY;
  sa_serv.sin_port = htons (PORT);      /* Server Port number */

  setsockopt (listen_sd, SOL_SOCKET, SO_REUSEADDR, (void *) &optval,
              sizeof (int));

  err = bind (listen_sd, (struct sockaddr *) & sa_serv, sizeof (sa_serv));
  SOCKET_ERR (err, "bind");
  err = listen (listen_sd, 1024);
  SOCKET_ERR (err, "listen");

  printf ("%s ready. Listening to port '%d'.\n\n", name, PORT);

  client_len = sizeof (sa_cli);
  for (;;)
    {
      session = initialize_tls_session ();

      sd = accept (listen_sd, (struct sockaddr *) & sa_cli, &client_len);

      printf ("- connection from %s, port %d\n",
              inet_ntop (AF_INET, &sa_cli.sin_addr, topbuf,
                         sizeof (topbuf)), ntohs (sa_cli.sin_port));

      gnutls_transport_set_ptr (session, (gnutls_transport_ptr_t) sd);

      do
        {
          ret = gnutls_handshake (session);
        }
      while (ret < 0 && gnutls_error_is_fatal (ret) == 0);

      if (ret < 0)
        {
          close (sd);
          gnutls_deinit (session);
          fprintf (stderr, "*** Handshake has failed (%s)\n\n",
                   gnutls_strerror (ret));
          continue;
        }
      printf ("- Handshake was completed\n");
      printf ("- User %s was connected\n", gnutls_srp_server_get_username(session));

      /* print_info(session); */

      for (;;)
        {
          memset (buffer, 0, MAX_BUF + 1);
          ret = gnutls_record_recv (session, buffer, MAX_BUF);

          if (ret == 0)
            {
              printf ("\n- Peer has closed the GnuTLS connection\n");
              break;
            }
          else if (ret < 0)
            {
              fprintf (stderr, "\n*** Received corrupted "
                       "data(%d). Closing the connection.\n\n", ret);
              break;
            }
          else if (ret > 0)
            {
              /* echo data back to the client
               */
              gnutls_record_send (session, buffer, strlen (buffer));
            }
        }
      printf ("\n");
      /* do not wait for the peer to close the connection. */
      gnutls_bye (session, GNUTLS_SHUT_WR);

      close (sd);
      gnutls_deinit (session);

    }
  close (listen_sd);

  gnutls_srp_free_server_credentials (srp_cred);
  gnutls_certificate_free_credentials (cert_cred);

  gnutls_global_deinit ();

  return 0;

}

Echo server with anonymous authentication

This example server supports anonymous authentication, and could be used to serve the example client for anonymous authentication.

/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <string.h>
#include <unistd.h>
#include <gnutls/gnutls.h>

/* This is a sample TLS 1.0 echo server, for anonymous authentication only.
 */

#define SOCKET_ERR(err,s) if(err==-1) {perror(s);return(1);}
#define MAX_BUF 1024
#define PORT 5556               /* listen to 5556 port */
#define DH_BITS 1024

/* These are global */
gnutls_anon_server_credentials_t anoncred;

static gnutls_session_t
initialize_tls_session (void)
{
  gnutls_session_t session;

  gnutls_init (&session, GNUTLS_SERVER);

  gnutls_priority_set_direct (session, "NORMAL:+ANON-ECDH:+ANON-DH", NULL);

  gnutls_credentials_set (session, GNUTLS_CRD_ANON, anoncred);

  gnutls_dh_set_prime_bits (session, DH_BITS);

  return session;
}

static gnutls_dh_params_t dh_params;

static int
generate_dh_params (void)
{

  /* Generate Diffie-Hellman parameters - for use with DHE
   * kx algorithms. These should be discarded and regenerated
   * once a day, once a week or once a month. Depending on the
   * security requirements.
   */
  gnutls_dh_params_init (&dh_params);
  gnutls_dh_params_generate2 (dh_params, DH_BITS);

  return 0;
}

int
main (void)
{
  int err, listen_sd;
  int sd, ret;
  struct sockaddr_in sa_serv;
  struct sockaddr_in sa_cli;
  socklen_t client_len;
  char topbuf[512];
  gnutls_session_t session;
  char buffer[MAX_BUF + 1];
  int optval = 1;

  /* this must be called once in the program
   */
  gnutls_global_init ();

  gnutls_anon_allocate_server_credentials (&anoncred);

  generate_dh_params ();

  gnutls_anon_set_server_dh_params (anoncred, dh_params);

  /* Socket operations
   */
  listen_sd = socket (AF_INET, SOCK_STREAM, 0);
  SOCKET_ERR (listen_sd, "socket");

  memset (&sa_serv, '\0', sizeof (sa_serv));
  sa_serv.sin_family = AF_INET;
  sa_serv.sin_addr.s_addr = INADDR_ANY;
  sa_serv.sin_port = htons (PORT);      /* Server Port number */

  setsockopt (listen_sd, SOL_SOCKET, SO_REUSEADDR, (void *) &optval,
              sizeof (int));

  err = bind (listen_sd, (struct sockaddr *) & sa_serv, sizeof (sa_serv));
  SOCKET_ERR (err, "bind");
  err = listen (listen_sd, 1024);
  SOCKET_ERR (err, "listen");

  printf ("Server ready. Listening to port '%d'.\n\n", PORT);

  client_len = sizeof (sa_cli);
  for (;;)
    {
      session = initialize_tls_session ();

      sd = accept (listen_sd, (struct sockaddr *) & sa_cli, &client_len);

      printf ("- connection from %s, port %d\n",
              inet_ntop (AF_INET, &sa_cli.sin_addr, topbuf,
                         sizeof (topbuf)), ntohs (sa_cli.sin_port));

      gnutls_transport_set_ptr (session, (gnutls_transport_ptr_t) ((ptrdiff_t) sd));

      do
        {
          ret = gnutls_handshake (session);
        }
      while (ret < 0 && gnutls_error_is_fatal (ret) == 0);

      if (ret < 0)
        {
          close (sd);
          gnutls_deinit (session);
          fprintf (stderr, "*** Handshake has failed (%s)\n\n",
                   gnutls_strerror (ret));
          continue;
        }
      printf ("- Handshake was completed\n");

      /* see the Getting peer's information example */
      /* print_info(session); */

      for (;;)
        {
          memset (buffer, 0, MAX_BUF + 1);
          ret = gnutls_record_recv (session, buffer, MAX_BUF);

          if (ret == 0)
            {
              printf ("\n- Peer has closed the GnuTLS connection\n");
              break;
            }
          else if (ret < 0)
            {
              fprintf (stderr, "\n*** Received corrupted "
                       "data(%d). Closing the connection.\n\n", ret);
              break;
            }
          else if (ret > 0)
            {
              /* echo data back to the client
               */
              gnutls_record_send (session, buffer, strlen (buffer));
            }
        }
      printf ("\n");
      /* do not wait for the peer to close the connection.
       */
      gnutls_bye (session, GNUTLS_SHUT_WR);

      close (sd);
      gnutls_deinit (session);

    }
  close (listen_sd);

  gnutls_anon_free_server_credentials (anoncred);

  gnutls_global_deinit ();

  return 0;

}

DTLS echo server with X.509 authentication

This example is a very simple echo server using Datagram TLS and X.509 authentication.

/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/select.h>
#include <netdb.h>
#include <string.h>
#include <unistd.h>
#include <gnutls/gnutls.h>
#include <gnutls/dtls.h>

#define KEYFILE "key.pem"
#define CERTFILE "cert.pem"
#define CAFILE "/etc/ssl/certs/ca-certificates.crt"
#define CRLFILE "crl.pem"

/* This is a sample DTLS echo server, using X.509 authentication.
 * Note that error checking is minimal to simplify the example.
 */

#define MAX_BUFFER 1024
#define PORT 5556

typedef struct
{
  gnutls_session_t session;
  int fd;
  struct sockaddr *cli_addr;
  socklen_t cli_addr_size;
} priv_data_st;

static int pull_timeout_func (gnutls_transport_ptr_t ptr, unsigned int ms);
static ssize_t push_func (gnutls_transport_ptr_t p, const void *data,
                          size_t size);
static ssize_t pull_func (gnutls_transport_ptr_t p, void *data, size_t size);
static const char *human_addr (const struct sockaddr *sa, socklen_t salen,
                               char *buf, size_t buflen);
static int wait_for_connection (int fd);
static gnutls_session_t initialize_tls_session (void);
static int generate_dh_params (void);

/* Use global credentials and parameters to simplify
 * the example. */
static gnutls_certificate_credentials_t x509_cred;
static gnutls_priority_t priority_cache;
static gnutls_dh_params_t dh_params;

int
main (void)
{
  int listen_sd;
  int sock, ret;
  struct sockaddr_in sa_serv;
  struct sockaddr_in cli_addr;
  socklen_t cli_addr_size;
  gnutls_session_t session;
  char buffer[MAX_BUFFER];
  priv_data_st priv;
  gnutls_datum_t cookie_key;
  gnutls_dtls_prestate_st prestate;
  int mtu = 1400;
  unsigned char sequence[8];

  /* this must be called once in the program
   */
  gnutls_global_init ();

  gnutls_certificate_allocate_credentials (&x509_cred);
  gnutls_certificate_set_x509_trust_file (x509_cred, CAFILE,
                                          GNUTLS_X509_FMT_PEM);

  gnutls_certificate_set_x509_crl_file (x509_cred, CRLFILE,
                                        GNUTLS_X509_FMT_PEM);

  ret = gnutls_certificate_set_x509_key_file (x509_cred, CERTFILE, KEYFILE,
                                        GNUTLS_X509_FMT_PEM);
  if (ret < 0)
    {
      printf("No certificate or key were found\n");
      exit(1);
    }

  generate_dh_params ();

  gnutls_certificate_set_dh_params (x509_cred, dh_params);

  gnutls_priority_init (&priority_cache,
                        "PERFORMANCE:-VERS-TLS-ALL:+VERS-DTLS1.0:%SERVER_PRECEDENCE",
                        NULL);

  gnutls_key_generate (&cookie_key, GNUTLS_COOKIE_KEY_SIZE);

  /* Socket operations
   */
  listen_sd = socket (AF_INET, SOCK_DGRAM, 0);

  memset (&sa_serv, '\0', sizeof (sa_serv));
  sa_serv.sin_family = AF_INET;
  sa_serv.sin_addr.s_addr = INADDR_ANY;
  sa_serv.sin_port = htons (PORT);

  { /* DTLS requires the IP don't fragment (DF) bit to be set */
#if defined(IP_DONTFRAG)
    int optval = 1;
    setsockopt (listen_sd, IPPROTO_IP, IP_DONTFRAG,
                (const void *) &optval, sizeof (optval));
#elif defined(IP_MTU_DISCOVER)
    int optval = IP_PMTUDISC_DO;
    setsockopt(listen_sd, IPPROTO_IP, IP_MTU_DISCOVER,
               (const void*) &optval, sizeof (optval));
#endif
  }

  bind (listen_sd, (struct sockaddr *) &sa_serv, sizeof (sa_serv));

  printf ("UDP server ready. Listening to port '%d'.\n\n", PORT);

  for (;;)
    {
      printf ("Waiting for connection...\n");
      sock = wait_for_connection (listen_sd);
      if (sock < 0)
        continue;

      cli_addr_size = sizeof (cli_addr);
      ret = recvfrom (sock, buffer, sizeof (buffer), MSG_PEEK,
                      (struct sockaddr *) &cli_addr, &cli_addr_size);
      if (ret > 0)
        {
          memset (&prestate, 0, sizeof (prestate));
          ret = gnutls_dtls_cookie_verify (&cookie_key, &cli_addr,
                                           sizeof (cli_addr), buffer, ret,
                                           &prestate);
          if (ret < 0)          /* cookie not valid */
            {
              priv_data_st s;

              memset (&s, 0, sizeof (s));
              s.fd = sock;
              s.cli_addr = (void *) &cli_addr;
              s.cli_addr_size = sizeof (cli_addr);

              printf ("Sending hello verify request to %s\n",
                      human_addr ((struct sockaddr *) &cli_addr,
                                  sizeof (cli_addr), buffer,
                                  sizeof (buffer)));

              gnutls_dtls_cookie_send (&cookie_key, &cli_addr,
                                       sizeof (cli_addr), &prestate,
                                       (gnutls_transport_ptr_t) & s,
                                       push_func);

              /* discard peeked data */
              recvfrom (sock, buffer, sizeof (buffer), 0,
                        (struct sockaddr *) &cli_addr, &cli_addr_size);
              usleep (100);
              continue;
            }
          printf ("Accepted connection from %s\n",
                  human_addr ((struct sockaddr *)
                              &cli_addr, sizeof (cli_addr), buffer,
                              sizeof (buffer)));
        }
      else
        continue;

      session = initialize_tls_session ();
      gnutls_dtls_prestate_set (session, &prestate);
      gnutls_dtls_set_mtu (session, mtu);

      priv.session = session;
      priv.fd = sock;
      priv.cli_addr = (struct sockaddr *) &cli_addr;
      priv.cli_addr_size = sizeof (cli_addr);

      gnutls_transport_set_ptr (session, &priv);
      gnutls_transport_set_push_function (session, push_func);
      gnutls_transport_set_pull_function (session, pull_func);
      gnutls_transport_set_pull_timeout_function (session, pull_timeout_func);

      do
        {
          ret = gnutls_handshake (session);
        }
      while (ret < 0 && gnutls_error_is_fatal (ret) == 0);

      if (ret < 0)
        {
          fprintf (stderr, "Error in handshake(): %s\n",
                   gnutls_strerror (ret));
          gnutls_deinit (session);
          continue;
        }

      printf ("- Handshake was completed\n");

      for (;;)
        {
          do
            {
              ret = gnutls_record_recv_seq (session, buffer, MAX_BUFFER,
                                            sequence);
            }
          while (ret == GNUTLS_E_AGAIN || ret == GNUTLS_E_INTERRUPTED);

          if (ret < 0)
            {
              fprintf (stderr, "Error in recv(): %s\n",
                       gnutls_strerror (ret));
              break;
            }
          if (ret == 0)
            {
              printf ("EOF\n\n");
              break;
            }
          buffer[ret] = 0;
          printf ("received[%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x]: %s\n",
                  sequence[0], sequence[1], sequence[2], sequence[3],
                  sequence[4], sequence[5], sequence[6], sequence[7], buffer);

          /* reply back */
          ret = gnutls_record_send (session, buffer, ret);
          if (ret < 0)
            {
              fprintf (stderr, "Error in send(): %s\n",
                       gnutls_strerror (ret));
              break;
            }
        }

      gnutls_bye (session, GNUTLS_SHUT_WR);
      gnutls_deinit (session);

    }
  close (listen_sd);

  gnutls_certificate_free_credentials (x509_cred);
  gnutls_priority_deinit (priority_cache);

  gnutls_global_deinit ();

  return 0;

}

static int
wait_for_connection (int fd)
{
  fd_set rd, wr;
  int n;

  FD_ZERO (&rd);
  FD_ZERO (&wr);

  FD_SET (fd, &rd);

  /* waiting part */
  n = select (fd + 1, &rd, &wr, NULL, NULL);
  if (n == -1 && errno == EINTR)
    return -1;
  if (n < 0)
    {
      perror ("select()");
      exit (1);
    }

  return fd;
}

/* Wait for data to be received within a timeout period in milliseconds
 */
static int
pull_timeout_func (gnutls_transport_ptr_t ptr, unsigned int ms)
{
  fd_set rfds;
  struct timeval tv;
  priv_data_st *priv = ptr;
  struct sockaddr_in cli_addr;
  socklen_t cli_addr_size;
  int ret;
  char c;

  FD_ZERO (&rfds);
  FD_SET (priv->fd, &rfds);

  tv.tv_sec = 0;
  tv.tv_usec = ms * 1000;

  ret = select (priv->fd + 1, &rfds, NULL, NULL, &tv);

  if (ret <= 0)
    return ret;

  /* only report ok if the next message is from the peer we expect
   * from
   */
  cli_addr_size = sizeof (cli_addr);
  ret =
    recvfrom (priv->fd, &c, 1, MSG_PEEK, (struct sockaddr *) &cli_addr,
              &cli_addr_size);
  if (ret > 0)
    {
      if (cli_addr_size == priv->cli_addr_size
          && memcmp (&cli_addr, priv->cli_addr, sizeof (cli_addr)) == 0)
        return 1;
    }

  return 0;
}

static ssize_t
push_func (gnutls_transport_ptr_t p, const void *data, size_t size)
{
  priv_data_st *priv = p;

  return sendto (priv->fd, data, size, 0, priv->cli_addr,
                 priv->cli_addr_size);
}

static ssize_t
pull_func (gnutls_transport_ptr_t p, void *data, size_t size)
{
  priv_data_st *priv = p;
  struct sockaddr_in cli_addr;
  socklen_t cli_addr_size;
  char buffer[64];
  int ret;

  cli_addr_size = sizeof (cli_addr);
  ret =
    recvfrom (priv->fd, data, size, 0, (struct sockaddr *) &cli_addr,
              &cli_addr_size);
  if (ret == -1)
    return ret;

  if (cli_addr_size == priv->cli_addr_size
      && memcmp (&cli_addr, priv->cli_addr, sizeof (cli_addr)) == 0)
    return ret;

  printf ("Denied connection from %s\n",
          human_addr ((struct sockaddr *)
                      &cli_addr, sizeof (cli_addr), buffer, sizeof (buffer)));

  gnutls_transport_set_errno (priv->session, EAGAIN);
  return -1;
}

static const char *
human_addr (const struct sockaddr *sa, socklen_t salen,
            char *buf, size_t buflen)
{
  const char *save_buf = buf;
  size_t l;

  if (!buf || !buflen)
    return NULL;

  *buf = '\0';

  switch (sa->sa_family)
    {
#if HAVE_IPV6
    case AF_INET6:
      snprintf (buf, buflen, "IPv6 ");
      break;
#endif

    case AF_INET:
      snprintf (buf, buflen, "IPv4 ");
      break;
    }

  l = strlen (buf);
  buf += l;
  buflen -= l;

  if (getnameinfo (sa, salen, buf, buflen, NULL, 0, NI_NUMERICHOST) != 0)
    return NULL;

  l = strlen (buf);
  buf += l;
  buflen -= l;

  strncat (buf, " port ", buflen);

  l = strlen (buf);
  buf += l;
  buflen -= l;

  if (getnameinfo (sa, salen, NULL, 0, buf, buflen, NI_NUMERICSERV) != 0)
    return NULL;

  return save_buf;
}

static gnutls_session_t
initialize_tls_session (void)
{
  gnutls_session_t session;

  gnutls_init (&session, GNUTLS_SERVER | GNUTLS_DATAGRAM);

  gnutls_priority_set (session, priority_cache);

  gnutls_credentials_set (session, GNUTLS_CRD_CERTIFICATE, x509_cred);

  return session;
}

static int
generate_dh_params (void)
{
  int bits = gnutls_sec_param_to_pk_bits (GNUTLS_PK_DH, GNUTLS_SEC_PARAM_LOW);

  /* Generate Diffie-Hellman parameters - for use with DHE
   * kx algorithms. When short bit length is used, it might
   * be wise to regenerate parameters often.
   */
  gnutls_dh_params_init (&dh_params);
  gnutls_dh_params_generate2 (dh_params, bits);

  return 0;
}

OCSP example

Generate OCSP request

A small tool to generate OCSP requests.

/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <gnutls/gnutls.h>
#include <gnutls/crypto.h>
#include <gnutls/ocsp.h>
#ifndef NO_LIBCURL
#include <curl/curl.h>
#endif
#include "read-file.h"

size_t get_data (void *buffer, size_t size, size_t nmemb,
                        void *userp);
static gnutls_x509_crt_t load_cert (const char *cert_file);
static void _response_info (const gnutls_datum_t * data);
static void
_generate_request (gnutls_datum_t * rdata, const char *cert_file,
                   const char *issuer_file);
static int _verify_response (gnutls_datum_t * data,
                             const char *signer_file);

/* This program queries an OCSP server.
   It expects three files. argv[1] containing the certificate to
   be checked, argv[2] holding the issuer for this certificate,
   and argv[3] holding a trusted certificate to verify OCSP's response.
   argv[4] is optional and should hold the server host name.

   For simplicity the libcurl library is used.
 */

int
main (int argc, char *argv[])
{
    gnutls_datum_t ud, tmp;
    int ret;
    gnutls_datum_t req;
#ifndef NO_LIBCURL
    CURL *handle;
    struct curl_slist *headers = NULL;
#endif
    int v, seq;
    const char *cert_file = argv[1];
    const char *issuer_file = argv[2];
    const char *signer_file = argv[3];
    char *hostname = NULL;

    gnutls_global_init ();

    if (argc > 4)
        hostname = argv[4];

    if (hostname == NULL)
      {
          gnutls_x509_crt_t cert = load_cert (cert_file);

          for (seq = 0;; seq++)
            {
                ret = gnutls_x509_crt_get_authority_info_access (cert, seq,
                                                                 GNUTLS_IA_OCSP_URI,
                                                                 &tmp,
                                                                 NULL);
                if (ret == GNUTLS_E_UNKNOWN_ALGORITHM)
                    continue;
                if (ret == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE)
                  {
                      fprintf (stderr,
                               "No URI was found in the certificate.\n");
                      exit (1);
                  }
                if (ret < 0)
                  {
                      fprintf (stderr, "error: %s\n",
                               gnutls_strerror (ret));
                      exit (1);
                  }

                printf ("CA issuers URI: %.*s\n", tmp.size, tmp.data);

                hostname = malloc (tmp.size + 1);
                memcpy (hostname, tmp.data, tmp.size);
                hostname[tmp.size] = 0;

                gnutls_free (tmp.data);
                break;
            }

          gnutls_x509_crt_deinit (cert);
      }

    /* Note that the OCSP servers hostname might be available
     * using gnutls_x509_crt_get_authority_info_access() in the issuer's
     * certificate */

    memset (&ud, 0, sizeof (ud));
    fprintf (stderr, "Connecting to %s\n", hostname);

    _generate_request (&req, cert_file, issuer_file);

#ifndef NO_LIBCURL
    curl_global_init (CURL_GLOBAL_ALL);

    handle = curl_easy_init ();
    if (handle == NULL)
        exit (1);

    headers =
        curl_slist_append (headers,
                           "Content-Type: application/ocsp-request");

    curl_easy_setopt (handle, CURLOPT_HTTPHEADER, headers);
    curl_easy_setopt (handle, CURLOPT_POSTFIELDS, (void *) req.data);
    curl_easy_setopt (handle, CURLOPT_POSTFIELDSIZE, req.size);
    curl_easy_setopt (handle, CURLOPT_URL, hostname);
    curl_easy_setopt (handle, CURLOPT_WRITEFUNCTION, get_data);
    curl_easy_setopt (handle, CURLOPT_WRITEDATA, &ud);

    ret = curl_easy_perform (handle);
    if (ret != 0)
      {
          fprintf (stderr, "curl[%d] error %d\n", __LINE__, ret);
          exit (1);
      }

    curl_easy_cleanup (handle);
#endif

    _response_info (&ud);

    v = _verify_response (&ud, signer_file);

    gnutls_global_deinit ();

    return v;
}

static void
_response_info (const gnutls_datum_t * data)
{
    gnutls_ocsp_resp_t resp;
    int ret;
    gnutls_datum buf;

    ret = gnutls_ocsp_resp_init (&resp);
    if (ret < 0)
        exit (1);

    ret = gnutls_ocsp_resp_import (resp, data);
    if (ret < 0)
        exit (1);

    ret = gnutls_ocsp_resp_print (resp, GNUTLS_OCSP_PRINT_FULL, &buf);
    if (ret != 0)
        exit (1);

    printf ("%.*s", buf.size, buf.data);
    gnutls_free (buf.data);

    gnutls_ocsp_resp_deinit (resp);
}

static gnutls_x509_crt_t
load_cert (const char *cert_file)
{
    gnutls_x509_crt_t crt;
    int ret;
    gnutls_datum_t data;
    size_t size;

    ret = gnutls_x509_crt_init (&crt);
    if (ret < 0)
        exit (1);

    data.data = (void *) read_binary_file (cert_file, &size);
    data.size = size;

    if (!data.data)
      {
          fprintf (stderr, "Cannot open file: %s\n", cert_file);
          exit (1);
      }

    ret = gnutls_x509_crt_import (crt, &data, GNUTLS_X509_FMT_PEM);
    free (data.data);
    if (ret < 0)
      {
          fprintf (stderr, "Cannot import certificate in %s: %s\n",
                   cert_file, gnutls_strerror (ret));
          exit (1);
      }

    return crt;
}

static void
_generate_request (gnutls_datum_t * rdata, const char *cert_file,
                   const char *issuer_file)
{
    gnutls_ocsp_req_t req;
    int ret;
    gnutls_x509_crt_t issuer, cert;
    unsigned char noncebuf[23];
    gnutls_datum_t nonce = { noncebuf, sizeof (noncebuf) };

    ret = gnutls_ocsp_req_init (&req);
    if (ret < 0)
        exit (1);

    issuer = load_cert (issuer_file);
    cert = load_cert (cert_file);

    ret = gnutls_ocsp_req_add_cert (req, GNUTLS_DIG_SHA1, issuer, cert);
    if (ret < 0)
        exit (1);

    gnutls_x509_crt_deinit (issuer);
    gnutls_x509_crt_deinit (cert);

    ret = gnutls_rnd (GNUTLS_RND_RANDOM, nonce.data, nonce.size);
    if (ret < 0)
        exit (1);

    ret = gnutls_ocsp_req_set_nonce (req, 0, &nonce);
    if (ret < 0)
        exit (1);

    ret = gnutls_ocsp_req_export (req, rdata);
    if (ret != 0)
        exit (1);

    gnutls_ocsp_req_deinit (req);

    return;
}

static int
_verify_response (gnutls_datum_t * data, const char *signer_file)
{
    gnutls_ocsp_resp_t resp;
    int ret;
    size_t size;
    gnutls_x509_crt_t signer;
    unsigned verify;
    gnutls_datum_t dat;

    ret = gnutls_ocsp_resp_init (&resp);
    if (ret < 0)
        exit (1);

    ret = gnutls_ocsp_resp_import (resp, data);
    if (ret < 0)
        exit (1);

    ret = gnutls_x509_crt_init (&signer);
    if (ret < 0)
        exit (1);

    dat.data = (void *) read_binary_file (signer_file, &size);
    if (dat.data == NULL)
        exit (1);

    dat.size = size;

    ret = gnutls_x509_crt_import (signer, &dat, GNUTLS_X509_FMT_PEM);
    free (dat.data);
    if (ret < 0)
        exit (1);

    ret = gnutls_ocsp_resp_verify_direct (resp, signer, &verify, 0);
    if (ret < 0)
        exit (1);

    printf ("Verifying OCSP Response: ");
    if (verify == 0)
        printf ("Verification success!\n");
    else
        printf ("Verification error!\n");

    if (verify & GNUTLS_OCSP_VERIFY_SIGNER_NOT_FOUND)
        printf ("Signer cert not found\n");

    if (verify & GNUTLS_OCSP_VERIFY_SIGNER_KEYUSAGE_ERROR)
        printf ("Signer cert keyusage error\n");

    if (verify & GNUTLS_OCSP_VERIFY_UNTRUSTED_SIGNER)
        printf ("Signer cert is not trusted\n");

    if (verify & GNUTLS_OCSP_VERIFY_INSECURE_ALGORITHM)
        printf ("Insecure algorithm\n");

    if (verify & GNUTLS_OCSP_VERIFY_SIGNATURE_FAILURE)
        printf ("Signature failure\n");

    if (verify & GNUTLS_OCSP_VERIFY_CERT_NOT_ACTIVATED)
        printf ("Signer cert not yet activated\n");

    if (verify & GNUTLS_OCSP_VERIFY_CERT_EXPIRED)
        printf ("Signer cert expired\n");

    gnutls_ocsp_resp_deinit (resp);

    return verify;
}

size_t
get_data (void *buffer, size_t size, size_t nmemb, void *userp)
{
    gnutls_datum_t *ud = userp;

    size *= nmemb;

    ud->data = realloc (ud->data, size + ud->size);
    if (ud->data == NULL)
      {
          fprintf (stderr, "Not enough memory for the request\n");
          exit (1);
      }

    memcpy (&ud->data[ud->size], buffer, size);
    ud->size += size;

    return size;
}

Miscellaneous examples

Checking for an alert

This is a function that checks if an alert has been received in the current session.

/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <gnutls/gnutls.h>

#include "examples.h"

/* This function will check whether the given return code from
 * a gnutls function (recv/send), is an alert, and will print
 * that alert.
 */
void
check_alert (gnutls_session_t session, int ret)
{
  int last_alert;

  if (ret == GNUTLS_E_WARNING_ALERT_RECEIVED
      || ret == GNUTLS_E_FATAL_ALERT_RECEIVED)
    {
      last_alert = gnutls_alert_get (session);

      /* The check for renegotiation is only useful if we are
       * a server, and we had requested a rehandshake.
       */
      if (last_alert == GNUTLS_A_NO_RENEGOTIATION &&
          ret == GNUTLS_E_WARNING_ALERT_RECEIVED)
        printf ("* Received NO_RENEGOTIATION alert. "
                "Client Does not support renegotiation.\n");
      else
        printf ("* Received alert '%d': %s.\n", last_alert,
                gnutls_alert_get_name (last_alert));
    }
}

X.509 certificate parsing example

To demonstrate the X.509 parsing capabilities an example program is listed below. That program reads the peer’s certificate, and prints information about it.

/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <gnutls/gnutls.h>
#include <gnutls/x509.h>

#include "examples.h"

static const char *
bin2hex (const void *bin, size_t bin_size)
{
  static char printable[110];
  const unsigned char *_bin = bin;
  char *print;
  size_t i;

  if (bin_size > 50)
    bin_size = 50;

  print = printable;
  for (i = 0; i < bin_size; i++)
    {
      sprintf (print, "%.2x ", _bin[i]);
      print += 2;
    }

  return printable;
}

/* This function will print information about this session's peer
 * certificate.
 */
void
print_x509_certificate_info (gnutls_session_t session)
{
  char serial[40];
  char dn[256];
  size_t size;
  unsigned int algo, bits;
  time_t expiration_time, activation_time;
  const gnutls_datum_t *cert_list;
  unsigned int cert_list_size = 0;
  gnutls_x509_crt_t cert;
  gnutls_datum_t cinfo;

  /* This function only works for X.509 certificates.
   */
  if (gnutls_certificate_type_get (session) != GNUTLS_CRT_X509)
    return;

  cert_list = gnutls_certificate_get_peers (session, &cert_list_size);

  printf ("Peer provided %d certificates.\n", cert_list_size);

  if (cert_list_size > 0)
    {
      int ret;

      /* we only print information about the first certificate.
       */
      gnutls_x509_crt_init (&cert);

      gnutls_x509_crt_import (cert, &cert_list[0], GNUTLS_X509_FMT_DER);

      printf ("Certificate info:\n");

      /* This is the preferred way of printing short information about
         a certificate. */

      ret = gnutls_x509_crt_print (cert, GNUTLS_CRT_PRINT_ONELINE, &cinfo);
      if (ret == 0)
        {
          printf ("\t%s\n", cinfo.data);
          gnutls_free (cinfo.data);
        }

      /* If you want to extract fields manually for some other reason,
         below are popular example calls. */

      expiration_time = gnutls_x509_crt_get_expiration_time (cert);
      activation_time = gnutls_x509_crt_get_activation_time (cert);

      printf ("\tCertificate is valid since: %s", ctime (&activation_time));
      printf ("\tCertificate expires: %s", ctime (&expiration_time));

      /* Print the serial number of the certificate.
       */
      size = sizeof (serial);
      gnutls_x509_crt_get_serial (cert, serial, &size);

      printf ("\tCertificate serial number: %s\n", bin2hex (serial, size));

      /* Extract some of the public key algorithm's parameters
       */
      algo = gnutls_x509_crt_get_pk_algorithm (cert, &bits);

      printf ("Certificate public key: %s",
              gnutls_pk_algorithm_get_name (algo));

      /* Print the version of the X.509
       * certificate.
       */
      printf ("\tCertificate version: #%d\n",
              gnutls_x509_crt_get_version (cert));

      size = sizeof (dn);
      gnutls_x509_crt_get_dn (cert, dn, &size);
      printf ("\tDN: %s\n", dn);

      size = sizeof (dn);
      gnutls_x509_crt_get_issuer_dn (cert, dn, &size);
      printf ("\tIssuer's DN: %s\n", dn);

      gnutls_x509_crt_deinit (cert);

    }
}

Listing the ciphersuites in a priority string

This is a small program to list the enabled ciphersuites by a priority string.

/* This example code is placed in the public domain. */

#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <gnutls/gnutls.h>

static void
print_cipher_suite_list (const char* priorities)
{
    size_t i;
    int ret;
    unsigned int idx;
    const char *name;
    const char *err;
    unsigned char id[2];
    gnutls_protocol_t version;
    gnutls_priority_t pcache;

    if (priorities != NULL)
      {
        printf ("Cipher suites for %s\n", priorities);

        ret = gnutls_priority_init(&pcache, priorities, &err);
        if (ret < 0)
          {
            fprintf (stderr, "Syntax error at: %s\n", err);
            exit(1);
          }

        for (i=0;;i++)
          {
            ret = gnutls_priority_get_cipher_suite_index(pcache, i, &idx);
            if (ret == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE) break;
            if (ret == GNUTLS_E_UNKNOWN_CIPHER_SUITE) continue;

            name = gnutls_cipher_suite_info(idx, id, NULL, NULL, NULL, &version);

            if (name != NULL)
              printf ("%-50s\t0x%02x, 0x%02x\t%s\n",
                      name, (unsigned char) id[0], (unsigned char) id[1],
                      gnutls_protocol_get_name (version));
          }

        return;
      }
}

int main(int argc, char** argv)
{
  if (argc > 1)
    print_cipher_suite_list (argv[1]);
}

Chapter 9. Other included programs

Included with GnuTLS are also a few command line tools that let you use the library for common tasks without writing an application. The applications are discussed in this chapter.

Invoking gnutls-cli

Simple client program to set up a TLS connection to some other computer. It sets up a TLS connection and forwards data from the standard input to the secured socket and vice versa.

This section was generated by AutoGen, using the agtexi-cmd template and the option descriptions for the gnutls-cli program. This software is released under the GNU General Public License, version 3 or later.

gnutls-cli usage (-h)

This is the automatically generated usage text for gnutls-cli:

gnutls-cli - GnuTLS client - Ver. @VERSION@
USAGE:  gnutls-cli [ -<flag> [<val>] | --<name>[{=| }<val>] ]... [hostname]

   -d, --debug=num            Enable debugging.
                                - It must be in the range:
                                  0 to 9999
   -V, --verbose              More verbose output
                                - may appear multiple times
       --tofu                 Enable trust on first use authentication
                                - disabled as --no-tofu
       --ocsp                 Enable OCSP certificate verification
                                - disabled as --no-ocsp
   -r, --resume               Establish a session and resume
   -e, --rehandshake          Establish a session and rehandshake
       --noticket             Don't accept session tickets
   -s, --starttls             Connect, establish a plain session and start TLS.
   -u, --udp                  Use DTLS (datagram TLS) over UDP
       --mtu=num              Set MTU for datagram TLS
                                - It must be in the range:
                                  0 to 17000
       --crlf                 Send CR LF instead of LF
       --x509fmtder           Use DER format for certificates to read from
   -f, --fingerprint          Send the openpgp fingerprint, instead of the key
       --disable-extensions   Disable all the TLS extensions
       --print-cert           Print peer's certificate in PEM format
       --recordsize=num       The maximum record size to advertize
                                - It must be in the range:
                                  0 to 4096
       --priority=str         Priorities string
       --x509cafile=str       Certificate file or PKCS #11 URL to use
       --x509crlfile=file     CRL file to use
                                - file must pre-exist
       --pgpkeyfile=file      PGP Key file to use
                                - file must pre-exist
       --pgpkeyring=file      PGP Key ring file to use
                                - file must pre-exist
       --pgpcertfile=file     PGP Public Key (certificate) file to use
                                - file must pre-exist
       --x509keyfile=str      X.509 key file or PKCS #11 URL to use
       --x509certfile=str     X.509 Certificate file or PKCS #11 URL to use
       --pgpsubkey=str        PGP subkey to use (hex or auto)
       --srpusername=str      SRP username to use
       --srppasswd=str        SRP password to use
       --pskusername=str      PSK username to use
       --pskkey=str           PSK key (in hex) to use
   -p, --port=str             The port or service to connect to
       --insecure             Don't abort program if server certificate can't be validated
       --benchmark-ciphers    Benchmark individual ciphers
       --benchmark-soft-ciphers  Benchmark individual software ciphers (no hw acceleration)
       --benchmark-tls        Benchmark ciphers and key exchange methods in TLS
   -l, --list                 Print a list of the supported algorithms and modes
   -v, --version[=arg]        Output version information and exit
   -h, --help                 Display extended usage information and exit
   -!, --more-help            Extended usage information passed thru pager

Options are specified by doubled hyphens and their name or by a single
hyphen and the flag character.
Operands and options may be intermixed.  They will be reordered.

Simple client program to set up a TLS connection to some other computer.
It sets up a TLS connection and forwards data from the standard input
to the secured socket and vice versa.

please send bug reports to:  bug-gnutls@gnu.org

benchmark-ciphers option

This is the “benchmark individual ciphers” option.

benchmark-soft-ciphers option

This is the “benchmark individual software ciphers (no hw acceleration)” option.

benchmark-tls option

This is the “benchmark ciphers and key exchange methods in tls” option.

crlf option

This is the “send cr lf instead of lf” option.

debug option (-d)

This is the “enable debugging.” option. Specifies the debug level.

disable-extensions option

This is the “disable all the tls extensions” option.

fingerprint option (-f)

This is the “send the openpgp fingerprint, instead of the key” option.

insecure option

This is the “don’t abort program if server certificate can’t be validated” option.

list option (-l)

This is the “print a list of the supported algorithms and modes” option. Print a list of the supported algorithms and modes. If a priority string is given then only the enabled ciphersuites are shown.

mtu option

This is the “set mtu for datagram tls” option.

noticket option

This is the “don’t accept session tickets” option.

ocsp option

This is the “enable ocsp certificate verification” option. This option will enable verification of the peer’s certificate using ocsp

pgpcertfile option

This is the “pgp public key (certificate) file to use” option.

pgpkeyfile option

This is the “pgp key file to use” option.

pgpkeyring option

This is the “pgp key ring file to use” option.

pgpsubkey option

This is the “pgp subkey to use (hex or auto)” option.

port option (-p)

This is the “the port or service to connect to” option.

print-cert option

This is the “print peer’s certificate in pem format” option.

priority option

This is the “priorities string” option. TLS algorithms and protocols to enable. You can use predefined sets of ciphersuites such as PERFORMANCE, NORMAL, SECURE128, SECURE256.

Check the GnuTLS manual on section “Priority strings” for more information on allowed keywords

pskkey option

This is the “psk key (in hex) to use” option.

pskusername option

This is the “psk username to use” option.

recordsize option

This is the “the maximum record size to advertize” option.

rehandshake option (-e)

This is the “establish a session and rehandshake” option. Connect, establish a session and rehandshake immediately.

resume option (-r)

This is the “establish a session and resume” option. Connect, establish a session, reconnect and resume.

srppasswd option

This is the “srp password to use” option.

srpusername option

This is the “srp username to use” option.

starttls option (-s)

This is the “connect, establish a plain session and start tls.” option. The TLS session will be initiated when EOF or a SIGALRM is received.

tofu option

This is the “enable trust on first use authentication” option. This option will, in addition to certificate authentication, perform authentication based on previously seen public keys, a model similar to SSH authentication.

udp option (-u)

This is the “use dtls (datagram tls) over udp” option.

verbose option (-V)

This is the “more verbose output” option.

This option has some usage constraints. It:

may appear an unlimited number of times.

x509cafile option

This is the “certificate file or pkcs #11 url to use” option.

x509certfile option

This is the “x.509 certificate file or pkcs #11 url to use” option.

x509crlfile option

This is the “crl file to use” option.

x509fmtder option

This is the “use der format for certificates to read from” option.

x509keyfile option

This is the “x.509 key file or pkcs #11 url to use” option.

gnutls-cli exit status

One of the following exit values will be returned:

‘0’

Successful program execution.

‘1’

The operation failed or the command syntax was not valid.

gnutls-cli See Also

gnutls-cli-debug(1), gnutls-serv(1)

gnutls-cli Examples

Connecting using PSK authentication

To connect to a server using PSK authentication, you need to enable the choice of PSK by using a cipher priority parameter such as in the example below.

$ ./gnutls-cli -p 5556 localhost --pskusername psk_identity \
    --pskkey 88f3824b3e5659f52d00e959bacab954b6540344 \
    --priority NORMAL:-KX-ALL:+ECDHE-PSK:+DHE-PSK:+PSK
Resolving 'localhost'...
Connecting to '127.0.0.1:5556'...
- PSK authentication.
- Version: TLS1.1
- Key Exchange: PSK
- Cipher: AES-128-CBC
- MAC: SHA1
- Compression: NULL
- Handshake was completed

- Simple Client Mode:

By keeping the –pskusername parameter and removing the –pskkey parameter, it will query only for the password during the handshake.

Listing ciphersuites in a priority string

To list the ciphersuites in a priority string:

$ ./gnutls-cli --priority SECURE192 -l
Cipher suites for SECURE192
TLS_ECDHE_ECDSA_AES_256_CBC_SHA384         0xc0, 0x24	TLS1.2
TLS_ECDHE_ECDSA_AES_256_GCM_SHA384         0xc0, 0x2e	TLS1.2
TLS_ECDHE_RSA_AES_256_GCM_SHA384           0xc0, 0x30	TLS1.2
TLS_DHE_RSA_AES_256_CBC_SHA256             0x00, 0x6b	TLS1.2
TLS_DHE_DSS_AES_256_CBC_SHA256             0x00, 0x6a	TLS1.2
TLS_RSA_AES_256_CBC_SHA256                 0x00, 0x3d	TLS1.2

Certificate types: CTYPE-X.509
Protocols: VERS-TLS1.2, VERS-TLS1.1, VERS-TLS1.0, VERS-SSL3.0, VERS-DTLS1.0
Compression: COMP-NULL
Elliptic curves: CURVE-SECP384R1, CURVE-SECP521R1
PK-signatures: SIGN-RSA-SHA384, SIGN-ECDSA-SHA384, SIGN-RSA-SHA512, SIGN-ECDSA-SHA512

Invoking gnutls-serv

Server program that listens to incoming TLS connections.

This section was generated by AutoGen, using the agtexi-cmd template and the option descriptions for the gnutls-serv program. This software is released under the GNU General Public License, version 3 or later.

gnutls-serv usage (-h)

This is the automatically generated usage text for gnutls-serv:

gnutls-serv - GnuTLS server - Ver. @VERSION@
USAGE:  gnutls-serv [ -<flag> [<val>] | --<name>[{=| }<val>] ]...

   -d, --debug=num            Enable debugging.
                                - It must be in the range:
                                  0 to 9999
       --noticket             Don't accept session tickets
   -g, --generate             Generate Diffie-Hellman and RSA-export parameters
   -q, --quiet                Suppress some messages
       --nodb                 Do not use a resumption database
       --http                 Act as an HTTP server
       --echo                 Act as an Echo server
   -u, --udp                  Use DTLS (datagram TLS) over UDP
       --mtu=num              Set MTU for datagram TLS
                                - It must be in the range:
                                  0 to 17000
   -a, --disable-client-cert  Do not request a client certificate
   -r, --require-client-cert  Require a client certificate
       --x509fmtder           Use DER format for certificates to read from
       --priority=str         Priorities string
       --dhparams=file        DH params file to use
                                - file must pre-exist
       --x509cafile=str       Certificate file or PKCS #11 URL to use
       --x509crlfile=file     CRL file to use
                                - file must pre-exist
       --pgpkeyfile=file      PGP Key file to use
                                - file must pre-exist
       --pgpkeyring=file      PGP Key ring file to use
                                - file must pre-exist
       --pgpcertfile=file     PGP Public Key (certificate) file to use
                                - file must pre-exist
       --x509keyfile=str      X.509 key file or PKCS #11 URL to use
       --x509certfile=str     X.509 Certificate file or PKCS #11 URL to use
       --x509dsakeyfile=str   Alternative X.509 key file or PKCS #11 URL to use
       --x509dsacertfile=str  Alternative X.509 Certificate file or PKCS #11 URL to use
       --x509ecckeyfile=str   Alternative X.509 key file or PKCS #11 URL to use
       --x509ecccertfile=str  Alternative X.509 Certificate file or PKCS #11 URL to use
       --pgpsubkey=str        PGP subkey to use (hex or auto)
       --srppasswd=file       SRP password file to use
                                - file must pre-exist
       --srppasswdconf=file   SRP password configuration file to use
                                - file must pre-exist
       --pskpasswd=file       PSK password file to use
                                - file must pre-exist
       --pskhint=str          PSK identity hint to use
   -p, --port=num             The port to connect to
   -l, --list                 Print a list of the supported algorithms and modes
   -v, --version[=arg]        Output version information and exit
   -h, --help                 Display extended usage information and exit
   -!, --more-help            Extended usage information passed thru pager

Options are specified by doubled hyphens and their name or by a single
hyphen and the flag character.

Server program that listens to incoming TLS connections.

please send bug reports to:  bug-gnutls@gnu.org

debug option (-d)

This is the “enable debugging.” option. Specifies the debug level.

dhparams option

This is the “dh params file to use” option.

disable-client-cert option (-a)

This is the “do not request a client certificate” option.

echo option

This is the “act as an echo server” option.

generate option (-g)

This is the “generate diffie-hellman and rsa-export parameters” option.

http option

This is the “act as an http server” option.

list option (-l)

This is the “print a list of the supported algorithms and modes” option. Print a list of the supported algorithms and modes. If a priority string is given then only the enabled ciphersuites are shown.

mtu option

This is the “set mtu for datagram tls” option.

nodb option

This is the “do not use a resumption database” option.

noticket option

This is the “don’t accept session tickets” option.

pgpcertfile option

This is the “pgp public key (certificate) file to use” option.

pgpkeyfile option

This is the “pgp key file to use” option.

pgpkeyring option

This is the “pgp key ring file to use” option.

pgpsubkey option

This is the “pgp subkey to use (hex or auto)” option.

port option (-p)

This is the “the port to connect to” option.

priority option

This is the “priorities string” option. TLS algorithms and protocols to enable. You can use predefined sets of ciphersuites such as PERFORMANCE, NORMAL, SECURE128, SECURE256.

Check the GnuTLS manual on section “Priority strings” for more information on allowed keywords

pskhint option

This is the “psk identity hint to use” option.

pskpasswd option

This is the “psk password file to use” option.

quiet option (-q)

This is the “suppress some messages” option.

require-client-cert option (-r)

This is the “require a client certificate” option.

srppasswd option

This is the “srp password file to use” option.

srppasswdconf option

This is the “srp password configuration file to use” option.

udp option (-u)

This is the “use dtls (datagram tls) over udp” option.

x509cafile option

This is the “certificate file or pkcs #11 url to use” option.

x509certfile option

This is the “x.509 certificate file or pkcs #11 url to use” option.

x509crlfile option

This is the “crl file to use” option.

x509dsacertfile option

This is the “alternative x.509 certificate file or pkcs #11 url to use” option.

x509dsakeyfile option

This is the “alternative x.509 key file or pkcs #11 url to use” option.

x509ecccertfile option

This is the “alternative x.509 certificate file or pkcs #11 url to use” option.

x509ecckeyfile option

This is the “alternative x.509 key file or pkcs #11 url to use” option.

x509fmtder option

This is the “use der format for certificates to read from” option.

x509keyfile option

This is the “x.509 key file or pkcs #11 url to use” option.

gnutls-serv exit status

One of the following exit values will be returned:

‘0’

Successful program execution.

‘1’

The operation failed or the command syntax was not valid.

gnutls-serv See Also

gnutls-cli-debug(1), gnutls-cli(1)

gnutls-serv Examples

Running your own TLS server based on GnuTLS can be useful when debugging clients and/or GnuTLS itself. This section describes how to use gnutls-serv as a simple HTTPS server.

The most basic server can be started as:

gnutls-serv --http

It will only support anonymous ciphersuites, which many TLS clients refuse to use.

The next step is to add support for X.509. First we generate a CA:

$ certtool --generate-privkey > x509-ca-key.pem
$ echo 'cn = GnuTLS test CA' > ca.tmpl
$ echo 'ca' >> ca.tmpl
$ echo 'cert_signing_key' >> ca.tmpl
$ certtool --generate-self-signed --load-privkey x509-ca-key.pem \
  --template ca.tmpl --outfile x509-ca.pem
...

Then generate a server certificate. Remember to change the dns_name value to the name of your server host, or skip that command to avoid the field.

$ certtool --generate-privkey > x509-server-key.pem
$ echo 'organization = GnuTLS test server' > server.tmpl
$ echo 'cn = test.gnutls.org' >> server.tmpl
$ echo 'tls_www_server' >> server.tmpl
$ echo 'encryption_key' >> server.tmpl
$ echo 'signing_key' >> server.tmpl
$ echo 'dns_name = test.gnutls.org' >> server.tmpl
$ certtool --generate-certificate --load-privkey x509-server-key.pem \
  --load-ca-certificate x509-ca.pem --load-ca-privkey x509-ca-key.pem \
  --template server.tmpl --outfile x509-server.pem
...

For use in the client, you may want to generate a client certificate as well.

$ certtool --generate-privkey > x509-client-key.pem
$ echo 'cn = GnuTLS test client' > client.tmpl
$ echo 'tls_www_client' >> client.tmpl
$ echo 'encryption_key' >> client.tmpl
$ echo 'signing_key' >> client.tmpl
$ certtool --generate-certificate --load-privkey x509-client-key.pem \
  --load-ca-certificate x509-ca.pem --load-ca-privkey x509-ca-key.pem \
  --template client.tmpl --outfile x509-client.pem
...

To be able to import the client key/certificate into some applications, you will need to convert them into a PKCS#12 structure. This also encrypts the security sensitive key with a password.

$ certtool --to-p12 --load-ca-certificate x509-ca.pem \
  --load-privkey x509-client-key.pem --load-certificate x509-client.pem \
  --outder --outfile x509-client.p12

For icing, we’ll create a proxy certificate for the client too.

$ certtool --generate-privkey > x509-proxy-key.pem
$ echo 'cn = GnuTLS test client proxy' > proxy.tmpl
$ certtool --generate-proxy --load-privkey x509-proxy-key.pem \
  --load-ca-certificate x509-client.pem --load-ca-privkey x509-client-key.pem \
  --load-certificate x509-client.pem --template proxy.tmpl \
  --outfile x509-proxy.pem
...

Then start the server again:

$ gnutls-serv --http \
            --x509cafile x509-ca.pem \
            --x509keyfile x509-server-key.pem \
            --x509certfile x509-server.pem

Try connecting to the server using your web browser. Note that the server listens to port 5556 by default.

While you are at it, to allow connections using DSA, you can also create a DSA key and certificate for the server. These credentials will be used in the final example below.

$ certtool --generate-privkey --dsa > x509-server-key-dsa.pem
$ certtool --generate-certificate --load-privkey x509-server-key-dsa.pem \
  --load-ca-certificate x509-ca.pem --load-ca-privkey x509-ca-key.pem \
  --template server.tmpl --outfile x509-server-dsa.pem
...

The next step is to create OpenPGP credentials for the server.

gpg --gen-key
...enter whatever details you want, use 'test.gnutls.org' as name...

Make a note of the OpenPGP key identifier of the newly generated key, here it was 5D1D14D8. You will need to export the key for GnuTLS to be able to use it.

gpg -a --export 5D1D14D8 > openpgp-server.txt
gpg --export 5D1D14D8 > openpgp-server.bin
gpg --export-secret-keys 5D1D14D8 > openpgp-server-key.bin
gpg -a --export-secret-keys 5D1D14D8 > openpgp-server-key.txt

Let’s start the server with support for OpenPGP credentials:

gnutls-serv --http \
            --pgpkeyfile openpgp-server-key.txt \
            --pgpcertfile openpgp-server.txt

The next step is to add support for SRP authentication. This requires an SRP password file created with srptool. To start the server with SRP support:

gnutls-serv --http \
            --srppasswdconf srp-tpasswd.conf \
            --srppasswd srp-passwd.txt

Let’s also start a server with support for PSK. This would require a password file created with psktool.

gnutls-serv --http \
            --pskpasswd psk-passwd.txt

Finally, we start the server with all the earlier parameters and you get this command:

gnutls-serv --http \
            --x509cafile x509-ca.pem \
            --x509keyfile x509-server-key.pem \
            --x509certfile x509-server.pem \
            --x509dsakeyfile x509-server-key-dsa.pem \
            --x509dsacertfile x509-server-dsa.pem \
            --pgpkeyfile openpgp-server-key.txt \
            --pgpcertfile openpgp-server.txt \
            --srppasswdconf srp-tpasswd.conf \
            --srppasswd srp-passwd.txt \
            --pskpasswd psk-passwd.txt

Invoking gnutls-cli-debug

TLS debug client. It sets up multiple TLS connections to a server and queries its capabilities. It was created to assist in debugging GnuTLS, but it might be useful to extract a TLS server’s capabilities. It connects to a TLS server, performs tests and print the server’s capabilities. If called with the ‘-v’ parameter more checks will be performed. Can be used to check for servers with special needs or bugs.

This section was generated by AutoGen, using the agtexi-cmd template and the option descriptions for the gnutls-cli-debug program. This software is released under the GNU General Public License, version 3 or later.

gnutls-cli-debug usage (-h)

This is the automatically generated usage text for gnutls-cli-debug:

gnutls-cli-debug - GnuTLS debug client - Ver. @VERSION@
USAGE:  gnutls-cli-debug [ -<flag> [<val>] | --<name>[{=| }<val>] ]...

   -d, --debug=num            Enable debugging.
                                - It must be in the range:
                                  0 to 9999
   -V, --verbose              More verbose output
                                - may appear multiple times
   -p, --port=num             The port to connect to
                                - It must be in the range:
                                  0 to 65536
   -v, --version[=arg]        Output version information and exit
   -h, --help                 Display extended usage information and exit
   -!, --more-help            Extended usage information passed thru pager

Options are specified by doubled hyphens and their name or by a single
hyphen and the flag character.
Operands and options may be intermixed.  They will be reordered.

TLS debug client. It sets up multiple TLS connections to a server
and queries its capabilities. It was created to assist in debugging
GnuTLS, but it might be useful to extract a TLS server's capabilities.
It connects to a TLS server, performs tests and print the server's
capabilities. If called with the `-v' parameter more checks will be
performed.  Can be used to check for servers with special needs or bugs.

please send bug reports to:  bug-gnutls@gnu.org

debug option (-d)

This is the “enable debugging.” option. Specifies the debug level.

port option (-p)

This is the “the port to connect to” option.

verbose option (-V)

This is the “more verbose output” option.

This option has some usage constraints. It:

may appear an unlimited number of times.

gnutls-cli-debug exit status

One of the following exit values will be returned:

‘0’

Successful program execution.

‘1’

The operation failed or the command syntax was not valid.

gnutls-cli-debug See Also

gnutls-cli(1), gnutls-serv(1)

gnutls-cli-debug Examples

$ ../src/gnutls-cli-debug localhost
Resolving 'localhost'...
Connecting to '127.0.0.1:443'...
Checking for SSL 3.0 support... yes
Checking whether %COMPAT is required... no
Checking for TLS 1.0 support... yes
Checking for TLS 1.1 support... no
Checking fallback from TLS 1.1 to... TLS 1.0
Checking for TLS 1.2 support... no
Checking whether we need to disable TLS 1.0... N/A
Checking for Safe renegotiation support... yes
Checking for Safe renegotiation support (SCSV)... yes
Checking for HTTPS server name... not checked
Checking for version rollback bug in RSA PMS... no
Checking for version rollback bug in Client Hello... no
Checking whether the server ignores the RSA PMS version... no
Checking whether the server can accept Hello Extensions... yes
Checking whether the server can accept small records (512 bytes)... yes
Checking whether the server can accept cipher suites not in SSL 3.0 spec... yes
Checking whether the server can accept a bogus TLS record version in the client hello... yes
Checking for certificate information... N/A
Checking for trusted CAs... N/A
Checking whether the server understands TLS closure alerts... partially
Checking whether the server supports session resumption... yes
Checking for export-grade ciphersuite support... no
Checking RSA-export ciphersuite info... N/A
Checking for anonymous authentication support... no
Checking anonymous Diffie-Hellman group info... N/A
Checking for ephemeral Diffie-Hellman support... no
Checking ephemeral Diffie-Hellman group info... N/A
Checking for ephemeral EC Diffie-Hellman support... yes
Checking ephemeral EC Diffie-Hellman group info...
 Curve SECP256R1
Checking for AES-GCM cipher support... no
Checking for AES-CBC cipher support... yes
Checking for CAMELLIA cipher support... no
Checking for 3DES-CBC cipher support... yes
Checking for ARCFOUR 128 cipher support... yes
Checking for ARCFOUR 40 cipher support... no
Checking for MD5 MAC support... yes
Checking for SHA1 MAC support... yes
Checking for SHA256 MAC support... no
Checking for ZLIB compression support... no
Checking for max record size... no
Checking for OpenPGP authentication support... no

Chapter 10. Internal Architecture of GnuTLS

This chapter is to give a brief description of the way GnuTLS works. The focus is to give an idea to potential developers and those who want to know what happens inside the black box.

The TLS Protocol

The main use case for the TLS protocol is shown in fig:client-server. A user of a library implementing the protocol expects no less than this functionality, i.e., to be able to set parameters such as the accepted security level, perform a negotiation with the peer and be able to exchange data.

TLS Handshake Protocol

The GnuTLS handshake protocol is implemented as a state machine that waits for input or returns immediately when the non-blocking transport layer functions are used. The main idea is shown in fig:gnutls-handshake.

Also the way the input is processed varies per ciphersuite. Several implementations of the internal handlers are available and gnutls_handshake only multiplexes the input to the appropriate handler. For example a PSK ciphersuite has a different implementation of the process_client_key_exchange than a certificate ciphersuite. We illustrate the idea in fig:gnutls-handshake-sequence.

TLS Authentication Methods

In GnuTLS authentication methods can be implemented quite easily. Since the required changes to add a new authentication method affect only the handshake protocol, a simple interface is used. An authentication method needs to implement the functions shown below.

typedef struct
{
  const char *name;
  int (*gnutls_generate_server_certificate) (gnutls_session_t, gnutls_buffer_st*);
  int (*gnutls_generate_client_certificate) (gnutls_session_t, gnutls_buffer_st*);
  int (*gnutls_generate_server_kx) (gnutls_session_t, gnutls_buffer_st*);
  int (*gnutls_generate_client_kx) (gnutls_session_t, gnutls_buffer_st*);
  int (*gnutls_generate_client_cert_vrfy) (gnutls_session_t, gnutls_buffer_st *);
  int (*gnutls_generate_server_certificate_request) (gnutls_session_t,
                                                     gnutls_buffer_st *);

  int (*gnutls_process_server_certificate) (gnutls_session_t, opaque *,
                                            size_t);
  int (*gnutls_process_client_certificate) (gnutls_session_t, opaque *,
                                            size_t);
  int (*gnutls_process_server_kx) (gnutls_session_t, opaque *, size_t);
  int (*gnutls_process_client_kx) (gnutls_session_t, opaque *, size_t);
  int (*gnutls_process_client_cert_vrfy) (gnutls_session_t, opaque *, size_t);
  int (*gnutls_process_server_certificate_request) (gnutls_session_t,
                                                    opaque *, size_t);
} mod_auth_st;

Those functions are responsible for the interpretation of the handshake protocol messages. It is common for such functions to read data from one or more credentials_t structures[16] and write data, such as certificates, usernames etc. to auth_info_t structures.

Simple examples of existing authentication methods can be seen in auth/psk.c for PSK ciphersuites and auth/srp.c for SRP ciphersuites. After implementing these functions the structure holding its pointers has to be registered in gnutls_algorithms.c in the _gnutls_kx_algorithms structure.

[16] such as the gnutls_certificate_credentials_t structures

TLS Extension Handling

As with authentication methods, the TLS extensions handlers can be implemented using the interface shown below.

typedef int (*gnutls_ext_recv_func) (gnutls_session_t session,
                                     const unsigned char *data, size_t len);
typedef int (*gnutls_ext_send_func) (gnutls_session_t session,
                                     gnutls_buffer_st *extdata);

Here there are two functions, one for receiving the extension data and one for sending. These functions have to check internally whether they operate in client or server side.

A simple example of an extension handler can be seen in ext/srp.c in GnuTLS’ source code. After implementing these functions, together with the extension number they handle, they have to be registered using _gnutls_ext_register in gnutls_extensions.c typically within _gnutls_ext_init.

Adding a new TLS extension

Adding support for a new TLS extension is done from time to time, and the process to do so is not difficult. Here are the steps you need to follow if you wish to do this yourself. For sake of discussion, let’s consider adding support for the hypothetical TLS extension foobar.

Add configure option like --enable-foobar or --disable-foobar.

This step is useful when the extension code is large and it might be desirable to disable the extension under some circumstances. Otherwise it can be safely skipped.

Whether to chose enable or disable depends on whether you intend to make the extension be enabled by default. Look at existing checks (i.e., SRP, authz) for how to model the code. For example:

AC_MSG_CHECKING([whether to disable foobar support])
AC_ARG_ENABLE(foobar,
	AS_HELP_STRING([--disable-foobar],
		[disable foobar support]),
	ac_enable_foobar=no)
if test x$ac_enable_foobar != xno; then
 AC_MSG_RESULT(no)
 AC_DEFINE(ENABLE_FOOBAR, 1, [enable foobar])
else
 ac_full=0
 AC_MSG_RESULT(yes)
fi
AM_CONDITIONAL(ENABLE_FOOBAR, test "$ac_enable_foobar" != "no")

These lines should go in lib/m4/hooks.m4.

Add IANA extension value to extensions_t in gnutls_int.h.

A good name for the value would be GNUTLS_EXTENSION_FOOBAR. Check with http://www.iana.org/assignments/tls-extensiontype-values for allocated values. For experiments, you could pick a number but remember that some consider it a bad idea to deploy such modified version since it will lead to interoperability problems in the future when the IANA allocates that number to someone else, or when the foobar protocol is allocated another number.

Add an entry to _gnutls_extensions in gnutls_extensions.c.

A typical entry would be:

  int ret;

#if ENABLE_FOOBAR
  ret = _gnutls_ext_register (&foobar_ext);
  if (ret != GNUTLS_E_SUCCESS)
    return ret;
#endif

Most likely you’ll need to add an #include "ext/foobar.h", that will contain something like like:

  extension_entry_st foobar_ext = {
    .name = "FOOBAR",
    .type = GNUTLS_EXTENSION_FOOBAR,
    .parse_type = GNUTLS_EXT_TLS,
    .recv_func = _foobar_recv_params,
    .send_func = _foobar_send_params,
    .pack_func = _foobar_pack,
    .unpack_func = _foobar_unpack,
    .deinit_func = NULL
  }

The GNUTLS_EXTENSION_FOOBAR is the integer value you added to gnutls_int.h earlier. In this structure you specify the functions to read the extension from the hello message, the function to send the reply to, and two more functions to pack and unpack from stored session data (e.g. when resumming a session). The deinit function will be called to deinitialize the extension’s private parameters, if any.

Note that the conditional ENABLE_FOOBAR definition should only be used if step 1 with the configure options has taken place.

Add new files that implement the extension.

The functions you are responsible to add are those mentioned in the previous step. They should be added in a file such as ext/foobar.c and headers should be placed in ext/foobar.h. As a starter, you could add this:

int
_foobar_recv_params (gnutls_session_t session, const opaque * data,
                     size_t data_size)
{
  return 0;
}

int
_foobar_send_params (gnutls_session_t session, gnutls_buffer_st* data)
{
  return 0;
}

int
_foobar_pack (extension_priv_data_t epriv, gnutls_buffer_st * ps)
{
   /* Append the extension's internal state to buffer */
   return 0;
}

int
_foobar_unpack (gnutls_buffer_st * ps, extension_priv_data_t * epriv)
{
   /* Read the internal state from buffer */
   return 0;
}

The _foobar_recv_params function is responsible for parsing incoming extension data (both in the client and server).

The _foobar_send_params function is responsible for sending extension data (both in the client and server).

If you receive length fields that don’t match, return GNUTLS_E_UNEXPECTED_PACKET_LENGTH. If you receive invalid data, return GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER. You can use other error codes from the list in Error codes. Return 0 on success.

An extension typically stores private information in the session data for later usage. That can be done using the functions _gnutls_ext_set_session_data and _gnutls_ext_get_session_data. You can check simple examples at ext/max_record.c and ext/server_name.c extensions. That private information can be saved and restored across session resumption if the following functions are set:

The _foobar_pack function is responsible for packing internal extension data to save them in the session resumption storage.

The _foobar_unpack function is responsible for restoring session data from the session resumption storage.

Recall that both the client and server, send and receive parameters, and your code most likely will need to do different things depending on which mode it is in. It may be useful to make this distinction explicit in the code. Thus, for example, a better template than above would be:

int
_gnutls_foobar_recv_params (gnutls_session_t session,
                            const opaque * data,
                            size_t data_size)
{
  if (session->security_parameters.entity == GNUTLS_CLIENT)
    return foobar_recv_client (session, data, data_size);
  else
    return foobar_recv_server (session, data, data_size);
}

int
_gnutls_foobar_send_params (gnutls_session_t session,
                            gnutls_buffer_st * data)
{
  if (session->security_parameters.entity == GNUTLS_CLIENT)
    return foobar_send_client (session, data);
  else
    return foobar_send_server (session, data);
}

The functions used would be declared as static functions, of the appropriate prototype, in the same file. When adding the files, you’ll need to add them to ext/Makefile.am as well, for example:

if ENABLE_FOOBAR
libgnutls_ext_la_SOURCES += ext/foobar.c ext/foobar.h
endif

Add API functions to enable/disable the extension.

It might be desirable to allow users of the extension to request use of the extension, or set extension specific data. This can be implemented by adding extension specific function calls that can be added to includes/gnutls/gnutls.h, as long as the LGPLv3+ applies. The implementation of the function should lie in the ext/foobar.c file.

To make the API available in the shared library you need to add the symbol in lib/libgnutls.map, so that the symbol is exported properly.

When writing GTK-DOC style documentation for your new APIs, don’t forget to add Since: tags to indicate the GnuTLS version the API was introduced in.

Adding a new Supplemental Data Handshake Message

TLS handshake extensions allow to send so called supplemental data handshake messages [RFC4680]. This short section explains how to implement a supplemental data handshake message for a given TLS extension.

First of all, modify your extension foobar in the way, the that flags session->security_parameters.do_send_supplemental and session->security_parameters.do_recv_supplemental are set:

int
_gnutls_foobar_recv_params (gnutls_session_t session, const opaque * data,
                                 size_t _data_size)
{
   ...
   session->security_parameters.do_recv_supplemental=1;
   ...
}

int
_gnutls_foobar_send_params (gnutls_session_t session, gnutls_buffer_st *extdata)
{
   ...
   session->security_parameters.do_send_supplemental=1;
   ...
}

Furthermore add the functions _foobar_supp_recv_params and _foobar_supp_send_params to _foobar.h and _foobar.c. The following example code shows how to send a “Hello World” string in the supplemental data handshake message:

int
_foobar_supp_recv_params(gnutls_session_t session, const opaque *data, size_t _data_size)
{
   uint8_t len = _data_size;
   unsigned char *msg;

   msg = gnutls_malloc(len);
   if (msg == NULL) return GNUTLS_E_MEMORY_ERROR;

   memcpy(msg, data, len);
   msg[len]='\0';

   /* do something with msg */
   gnutls_free(msg);

   return len;
}

int
_foobar_supp_send_params(gnutls_session_t session, gnutls_buffer_st *buf)
{
   unsigned char *msg = "hello world";
   int len = strlen(msg);

   _gnutls_buffer_append_data_prefix(buf, 8, msg, len);

   return len;
}

Afterwards, add the new supplemental data handshake message to lib/gnutls_supplemental.c by adding a new entry to the _gnutls_supplemental[] structure:

gnutls_supplemental_entry _gnutls_supplemental[] =
{
  {"foobar",
   GNUTLS_SUPPLEMENTAL_FOOBAR_DATA,
   _foobar_supp_recv_params,
   _foobar_supp_send_params},
  {0, 0, 0, 0}
};

You have to include your foobar.h header file as well:

#include "foobar.h"

Lastly, add the new supplemental data type to lib/includes/gnutls/gnutls.h:

typedef enum
{
    GNUTLS_SUPPLEMENTAL_USER_MAPPING_DATA = 0,
    GNUTLS_SUPPLEMENTAL_FOOBAR_DATA = 1
} gnutls_supplemental_data_format_type_t;

Cryptographic Backend

Today most new processors, either for embedded or desktop systems include either instructions intended to speed up cryptographic operations, or a co-processor with cryptographic capabilities. Taking advantage of those is a challenging task for every cryptographic application or library. Unfortunately the cryptographic library that GnuTLS is based on takes no advantage of these capabilities. For this reason GnuTLS handles this internally by following a layered approach to accessing cryptographic operations as in fig:crypto-layers.

The TLS layer uses a cryptographic provider layer, that will in turn either use the default crypto provider – a software crypto library, or use an external crypto provider, if available in the local system. The reason of handling the external cryptographic provider in GnuTLS and not delegating it to the cryptographic libraries, is that none of the supported cryptographic libraries support /dev/crypto or CPU-optimized cryptography in an efficient way.

Cryptographic library layer

The Cryptographic library layer, currently supports only libnettle. Older versions of GnuTLS used to support libgcrypt, but it was switched with nettle mainly for performance reasons[17] and secondary because it is a simpler library to use. In the future other cryptographic libraries might be supported as well.

External cryptography provider

Systems that include a cryptographic co-processor, typically come with kernel drivers to utilize the operations from software. For this reason GnuTLS provides a layer where each individual algorithm used can be replaced by another implementation, i.e., the one provided by the driver. The FreeBSD, OpenBSD and Linux kernels[18] include already a number of hardware assisted implementations, and also provide an interface to access them, called /dev/crypto. GnuTLS will take advantage of this interface if compiled with special options. That is because in most systems where hardware-assisted cryptographic operations are not available, using this interface might actually harm performance.

In systems that include cryptographic instructions with the CPU’s instructions set, using the kernel interface will introduce an unneeded layer. For this reason GnuTLS includes such optimizations found in popular processors such as the AES-NI or VIA PADLOCK instruction sets. This is achieved using a mechanism that detects CPU capabilities and overrides parts of crypto back-end at runtime. The next section discusses the registration of a detected algorithm optimization. For more information please consult the GnuTLS source code in lib/accelerated/.

Overriding specific algorithms

When an optimized implementation of a single algorithm is available, say a hardware assisted version of AES-CBC then the following (internal) functions, from crypto-backend.h, can be used to register those algorithms.

gnutls_crypto_single_cipher_register: To register a cipher algorithm.

gnutls_crypto_single_digest_register: To register a hash (digest) or MAC algorithm.

Those registration functions will only replace the specified algorithm and leave the rest of subsystem intact.

Overriding the cryptographic library

In some systems, that might contain a broad acceleration engine, it might be desirable to override big parts of the cryptographic back-end, or even all of them. The following functions are provided for this reason.

gnutls_crypto_cipher_register: To override the cryptographic algorithms back-end.

gnutls_crypto_digest_register: To override the digest algorithms back-end.

gnutls_crypto_rnd_register: To override the random number generator back-end.

gnutls_crypto_bigint_register: To override the big number number operations back-end.

gnutls_crypto_pk_register: To override the public key encryption back-end. This is tied to the big number operations so either none or both of them should be overriden.

[17] See http://lists.gnu.org/archive/html/gnutls-devel/2011-02/msg00079.html.

[18] Check http://home.gna.org/cryptodev-linux/ for the Linux kernel implementation of /dev/crypto.

Appendix A. Support

Getting Help

A mailing list where users may help each other exists, and you can reach it by sending e-mail to <help-gnutls@gnu.org>. Archives of the mailing list discussions, and an interface to manage subscriptions, is available through the World Wide Web at http://lists.gnu.org/mailman/listinfo/help-gnutls.

A mailing list for developers are also available, see http://www.gnu.org/software/gnutls/lists.html. Bug reports should be sent to <bug-gnutls@gnu.org>, see Bug Reports.

Commercial Support

Commercial support is available for users of GnuTLS. The kind of support that can be purchased may include:

Implement new features. Such as a new TLS extension.

Port GnuTLS to new platforms. This could include porting to an embedded platforms that may need memory or size optimization.

Integrating TLS as a security environment in your existing project.

System design of components related to TLS.

If you are interested, please write to:

Simon Josefsson Datakonsult
Hagagatan 24
113 47 Stockholm
Sweden

E-mail: simon@josefsson.org

If your company provides support related to GnuTLS and would like to be mentioned here, contact the authors.

Bug Reports

If you think you have found a bug in GnuTLS, please investigate it and report it.

Please make sure that the bug is really in GnuTLS, and preferably also check that it hasn’t already been fixed in the latest version.

You have to send us a test case that makes it possible for us to reproduce the bug.

You also have to explain what is wrong; if you get a crash, or if the results printed are not good and in that case, in what way. Make sure that the bug report includes all information you would need to fix this kind of bug for someone else.

Please make an effort to produce a self-contained report, with something definite that can be tested or debugged. Vague queries or piecemeal messages are difficult to act on and don’t help the development effort.

If your bug report is good, we will do our best to help you to get a corrected version of the software; if the bug report is poor, we won’t do anything about it (apart from asking you to send better bug reports).

If you think something in this manual is unclear, or downright incorrect, or if the language needs to be improved, please also send a note.

Send your bug report to:

‘bug-gnutls@gnu.org’

Contributing

If you want to submit a patch for inclusion – from solving a typo you discovered, up to adding support for a new feature – you should submit it as a bug report, using the process in Bug Reports. There are some things that you can do to increase the chances for it to be included in the official package.

Unless your patch is very small (say, under 10 lines) we require that you assign the copyright of your work to the Free Software Foundation. This is to protect the freedom of the project. If you have not already signed papers, we will send you the necessary information when you submit your contribution.

For contributions that doesn’t consist of actual programming code, the only guidelines are common sense. For code contributions, a number of style guides will help you:

Coding Style. Follow the GNU Standards document.

If you normally code using another coding standard, there is no problem, but you should use ‘indent’ to reformat the code before submitting your work.

Use the unified diff format ‘diff -u’.

Return errors. No reason whatsoever should abort the execution of the library. Even memory allocation errors, e.g. when malloc return NULL, should work although result in an error code.

Design with thread safety in mind. Don’t use global variables. Don’t even write to per-handle global variables unless the documented behaviour of the function you write is to write to the per-handle global variable.

Avoid using the C math library. It causes problems for embedded implementations, and in most situations it is very easy to avoid using it.

Document your functions. Use comments before each function headers, that, if properly formatted, are extracted into Texinfo manuals and GTK-DOC web pages.

Supply a ChangeLog and NEWS entries, where appropriate.

Appendix B. Error Codes and Descriptions

The error codes used throughout the library are described below. The return code GNUTLS_E_SUCCESS indicate successful operation, and is guaranteed to have the value 0, so you can use it in logical expressions.

0

GNUTLS_E_SUCCESS

Success.

-3

GNUTLS_E_UNKNOWN_COMPRESSION_ALGORITHM

Could not negotiate a supported compression method.

-6

GNUTLS_E_UNKNOWN_CIPHER_TYPE

The cipher type is unsupported.

-7

GNUTLS_E_LARGE_PACKET

A large TLS record packet was received.

-8

GNUTLS_E_UNSUPPORTED_VERSION_PACKET

A record packet with illegal version was received.

-9

GNUTLS_E_UNEXPECTED_PACKET_LENGTH

A TLS packet with unexpected length was received.

-10

GNUTLS_E_INVALID_SESSION

The specified session has been invalidated for some reason.

-12

GNUTLS_E_FATAL_ALERT_RECEIVED

A TLS fatal alert has been received.

-15

GNUTLS_E_UNEXPECTED_PACKET

An unexpected TLS packet was received.

-16

GNUTLS_E_WARNING_ALERT_RECEIVED

A TLS warning alert has been received.

-18

GNUTLS_E_ERROR_IN_FINISHED_PACKET

An error was encountered at the TLS Finished packet calculation.

-19

GNUTLS_E_UNEXPECTED_HANDSHAKE_PACKET

An unexpected TLS handshake packet was received.

-21

GNUTLS_E_UNKNOWN_CIPHER_SUITE

Could not negotiate a supported cipher suite.

-22

GNUTLS_E_UNWANTED_ALGORITHM

An algorithm that is not enabled was negotiated.

-23

GNUTLS_E_MPI_SCAN_FAILED

The scanning of a large integer has failed.

-24

GNUTLS_E_DECRYPTION_FAILED

Decryption has failed.

-25

GNUTLS_E_MEMORY_ERROR

Internal error in memory allocation.

-26

GNUTLS_E_DECOMPRESSION_FAILED

Decompression of the TLS record packet has failed.

-27

GNUTLS_E_COMPRESSION_FAILED

Compression of the TLS record packet has failed.

-28

GNUTLS_E_AGAIN

Resource temporarily unavailable, try again.

-29

GNUTLS_E_EXPIRED

The requested session has expired.

-30

GNUTLS_E_DB_ERROR

Error in Database backend.

-31

GNUTLS_E_SRP_PWD_ERROR

Error in password file.

-32

GNUTLS_E_INSUFFICIENT_CREDENTIALS

Insufficient credentials for that request.

-33

GNUTLS_E_HASH_FAILED

Hashing has failed.

-34

GNUTLS_E_BASE64_DECODING_ERROR

Base64 decoding error.

-35

GNUTLS_E_MPI_PRINT_FAILED

Could not export a large integer.

-37

GNUTLS_E_REHANDSHAKE

Rehandshake was requested by the peer.

-38

GNUTLS_E_GOT_APPLICATION_DATA

TLS Application data were received, while expecting handshake data.

-39

GNUTLS_E_RECORD_LIMIT_REACHED

The upper limit of record packet sequence numbers has been reached. Wow!

-40

GNUTLS_E_ENCRYPTION_FAILED

Encryption has failed.

-43

GNUTLS_E_CERTIFICATE_ERROR

Error in the certificate.

-44

GNUTLS_E_PK_ENCRYPTION_FAILED

Public key encryption has failed.

-45

GNUTLS_E_PK_DECRYPTION_FAILED

Public key decryption has failed.

-46

GNUTLS_E_PK_SIGN_FAILED

Public key signing has failed.

-47

GNUTLS_E_X509_UNSUPPORTED_CRITICAL_EXTENSION

Unsupported critical extension in X.509 certificate.

-48

GNUTLS_E_KEY_USAGE_VIOLATION

Key usage violation in certificate has been detected.

-49

GNUTLS_E_NO_CERTIFICATE_FOUND

No certificate was found.

-50

GNUTLS_E_INVALID_REQUEST

The request is invalid.

-51

GNUTLS_E_SHORT_MEMORY_BUFFER

The given memory buffer is too short to hold parameters.

-52

GNUTLS_E_INTERRUPTED

Function was interrupted.

-53

GNUTLS_E_PUSH_ERROR

Error in the push function.

-54

GNUTLS_E_PULL_ERROR

Error in the pull function.

-55

GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER

An illegal parameter has been received.

-56

GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE

The requested data were not available.

-57

GNUTLS_E_PKCS1_WRONG_PAD

Wrong padding in PKCS1 packet.

-58

GNUTLS_E_RECEIVED_ILLEGAL_EXTENSION

An illegal TLS extension was received.

-59

GNUTLS_E_INTERNAL_ERROR

GnuTLS internal error.

-60

GNUTLS_E_CERTIFICATE_KEY_MISMATCH

The certificate and the given key do not match.

-61

GNUTLS_E_UNSUPPORTED_CERTIFICATE_TYPE

The certificate type is not supported.

-62

GNUTLS_E_X509_UNKNOWN_SAN

Unknown Subject Alternative name in X.509 certificate.

-63

GNUTLS_E_DH_PRIME_UNACCEPTABLE

The Diffie-Hellman prime sent by the server is not acceptable (not long enough).

-64

GNUTLS_E_FILE_ERROR

Error while reading file.

-67

GNUTLS_E_ASN1_ELEMENT_NOT_FOUND

ASN1 parser: Element was not found.

-68

GNUTLS_E_ASN1_IDENTIFIER_NOT_FOUND

ASN1 parser: Identifier was not found

-69

GNUTLS_E_ASN1_DER_ERROR

ASN1 parser: Error in DER parsing.

-70

GNUTLS_E_ASN1_VALUE_NOT_FOUND

ASN1 parser: Value was not found.

-71

GNUTLS_E_ASN1_GENERIC_ERROR

ASN1 parser: Generic parsing error.

-72

GNUTLS_E_ASN1_VALUE_NOT_VALID

ASN1 parser: Value is not valid.

-73

GNUTLS_E_ASN1_TAG_ERROR

ASN1 parser: Error in TAG.

-74

GNUTLS_E_ASN1_TAG_IMPLICIT

ASN1 parser: error in implicit tag

-75

GNUTLS_E_ASN1_TYPE_ANY_ERROR

ASN1 parser: Error in type ’ANY’.

-76

GNUTLS_E_ASN1_SYNTAX_ERROR

ASN1 parser: Syntax error.

-77

GNUTLS_E_ASN1_DER_OVERFLOW

ASN1 parser: Overflow in DER parsing.

-78

GNUTLS_E_TOO_MANY_EMPTY_PACKETS

Too many empty record packets have been received.

-79

GNUTLS_E_OPENPGP_UID_REVOKED

The OpenPGP User ID is revoked.

-80

GNUTLS_E_UNKNOWN_PK_ALGORITHM

An unknown public key algorithm was encountered.

-81

GNUTLS_E_TOO_MANY_HANDSHAKE_PACKETS

Too many handshake packets have been received.

-84

GNUTLS_E_NO_TEMPORARY_RSA_PARAMS

No temporary RSA parameters were found.

-86

GNUTLS_E_NO_COMPRESSION_ALGORITHMS

No supported compression algorithms have been found.

-87

GNUTLS_E_NO_CIPHER_SUITES

No supported cipher suites have been found.

-88

GNUTLS_E_OPENPGP_GETKEY_FAILED

Could not get OpenPGP key.

-89

GNUTLS_E_PK_SIG_VERIFY_FAILED

Public key signature verification has failed.

-90

GNUTLS_E_ILLEGAL_SRP_USERNAME

The SRP username supplied is illegal.

-91

GNUTLS_E_SRP_PWD_PARSING_ERROR

Parsing error in password file.

-93

GNUTLS_E_NO_TEMPORARY_DH_PARAMS

No temporary DH parameters were found.

-94

GNUTLS_E_OPENPGP_FINGERPRINT_UNSUPPORTED

The OpenPGP fingerprint is not supported.

-95

GNUTLS_E_X509_UNSUPPORTED_ATTRIBUTE

The certificate has unsupported attributes.

-96

GNUTLS_E_UNKNOWN_HASH_ALGORITHM

The hash algorithm is unknown.

-97

GNUTLS_E_UNKNOWN_PKCS_CONTENT_TYPE

The PKCS structure’s content type is unknown.

-98

GNUTLS_E_UNKNOWN_PKCS_BAG_TYPE

The PKCS structure’s bag type is unknown.

-99

GNUTLS_E_INVALID_PASSWORD

The given password contains invalid characters.

-100

GNUTLS_E_MAC_VERIFY_FAILED

The Message Authentication Code verification failed.

-101

GNUTLS_E_CONSTRAINT_ERROR

Some constraint limits were reached.

-102

GNUTLS_E_WARNING_IA_IPHF_RECEIVED

Received a TLS/IA Intermediate Phase Finished message

-103

GNUTLS_E_WARNING_IA_FPHF_RECEIVED

Received a TLS/IA Final Phase Finished message

-104

GNUTLS_E_IA_VERIFY_FAILED

Verifying TLS/IA phase checksum failed

-105

GNUTLS_E_UNKNOWN_ALGORITHM

The specified algorithm or protocol is unknown.

-106

GNUTLS_E_UNSUPPORTED_SIGNATURE_ALGORITHM

The signature algorithm is not supported.

-107

GNUTLS_E_SAFE_RENEGOTIATION_FAILED

Safe renegotiation failed.

-108

GNUTLS_E_UNSAFE_RENEGOTIATION_DENIED

Unsafe renegotiation denied.

-109

GNUTLS_E_UNKNOWN_SRP_USERNAME

The SRP username supplied is unknown.

-110

GNUTLS_E_PREMATURE_TERMINATION

The TLS connection was non-properly terminated.

-201

GNUTLS_E_BASE64_ENCODING_ERROR

Base64 encoding error.

-202

GNUTLS_E_INCOMPATIBLE_GCRYPT_LIBRARY

The crypto library version is too old.

-203

GNUTLS_E_INCOMPATIBLE_LIBTASN1_LIBRARY

The tasn1 library version is too old.

-204

GNUTLS_E_OPENPGP_KEYRING_ERROR

Error loading the keyring.

-205

GNUTLS_E_X509_UNSUPPORTED_OID

The OID is not supported.

-206

GNUTLS_E_RANDOM_FAILED

Failed to acquire random data.

-207

GNUTLS_E_BASE64_UNEXPECTED_HEADER_ERROR

Base64 unexpected header error.

-208

GNUTLS_E_OPENPGP_SUBKEY_ERROR

Could not find OpenPGP subkey.

-209

GNUTLS_E_CRYPTO_ALREADY_REGISTERED

There is already a crypto algorithm with lower priority.

-210

GNUTLS_E_HANDSHAKE_TOO_LARGE

The handshake data size is too large.

-211

GNUTLS_E_CRYPTODEV_IOCTL_ERROR

Error interfacing with /dev/crypto

-212

GNUTLS_E_CRYPTODEV_DEVICE_ERROR

Error opening /dev/crypto

-213

GNUTLS_E_CHANNEL_BINDING_NOT_AVAILABLE

Channel binding data not available

-214

GNUTLS_E_BAD_COOKIE

The cookie was bad.

-215

GNUTLS_E_OPENPGP_PREFERRED_KEY_ERROR

The OpenPGP key has not a preferred key set.

-216

GNUTLS_E_INCOMPAT_DSA_KEY_WITH_TLS_PROTOCOL

The given DSA key is incompatible with the selected TLS protocol.

-300

GNUTLS_E_PKCS11_ERROR

PKCS #11 error.

-301

GNUTLS_E_PKCS11_LOAD_ERROR

PKCS #11 initialization error.

-302

GNUTLS_E_PARSING_ERROR

Error in parsing.

-303

GNUTLS_E_PKCS11_PIN_ERROR

PKCS #11 error in PIN.

-305

GNUTLS_E_PKCS11_SLOT_ERROR

PKCS #11 error in slot

-306

GNUTLS_E_LOCKING_ERROR

Thread locking error

-307

GNUTLS_E_PKCS11_ATTRIBUTE_ERROR

PKCS #11 error in attribute

-308

GNUTLS_E_PKCS11_DEVICE_ERROR

PKCS #11 error in device

-309

GNUTLS_E_PKCS11_DATA_ERROR

PKCS #11 error in data

-310

GNUTLS_E_PKCS11_UNSUPPORTED_FEATURE_ERROR

PKCS #11 unsupported feature

-311

GNUTLS_E_PKCS11_KEY_ERROR

PKCS #11 error in key

-312

GNUTLS_E_PKCS11_PIN_EXPIRED

PKCS #11 PIN expired

-313

GNUTLS_E_PKCS11_PIN_LOCKED

PKCS #11 PIN locked

-314

GNUTLS_E_PKCS11_SESSION_ERROR

PKCS #11 error in session

-315

GNUTLS_E_PKCS11_SIGNATURE_ERROR

PKCS #11 error in signature

-316

GNUTLS_E_PKCS11_TOKEN_ERROR

PKCS #11 error in token

-317

GNUTLS_E_PKCS11_USER_ERROR

PKCS #11 user error

-318

GNUTLS_E_CRYPTO_INIT_FAILED

The initialization of crypto backend has failed.

-319

GNUTLS_E_TIMEDOUT

The operation timed out

-320

GNUTLS_E_USER_ERROR

The operation was cancelled due to user error

-321

GNUTLS_E_ECC_NO_SUPPORTED_CURVES

No supported ECC curves were found

-322

GNUTLS_E_ECC_UNSUPPORTED_CURVE

The curve is unsupported

-323

GNUTLS_E_PKCS11_REQUESTED_OBJECT_NOT_AVAILBLE

The requested PKCS #11 object is not available

-324

GNUTLS_E_CERTIFICATE_LIST_UNSORTED

The provided X.509 certificate list is not sorted (in subject to issuer order)

-325

GNUTLS_E_ILLEGAL_PARAMETER

An illegal parameter was found.

-326

GNUTLS_E_NO_PRIORITIES_WERE_SET

No or insufficient priorities were set.

-327

GNUTLS_E_X509_UNSUPPORTED_EXTENSION

Unsupported extension in X.509 certificate.

-328

GNUTLS_E_SESSION_EOF

Peer has terminated the connection

Appendix C. Supported Ciphersuites

Ciphersuites

Ciphersuite name

TLS ID

Since

TLS_DH_ANON_ARCFOUR_MD5

0x00 0x18

SSL3.0

TLS_DH_ANON_3DES_EDE_CBC_SHA1

0x00 0x1B

SSL3.0

TLS_DH_ANON_AES_128_CBC_SHA1

0x00 0x34

SSL3.0

TLS_DH_ANON_AES_256_CBC_SHA1

0x00 0x3A

SSL3.0

TLS_DH_ANON_CAMELLIA_128_CBC_SHA1

0x00 0x46

TLS1.0

TLS_DH_ANON_CAMELLIA_256_CBC_SHA1

0x00 0x89

TLS1.0

TLS_DH_ANON_AES_128_CBC_SHA256

0x00 0x6C

TLS1.2

TLS_DH_ANON_AES_256_CBC_SHA256

0x00 0x6D

TLS1.2

TLS_PSK_SHA_ARCFOUR_SHA1

0x00 0x8A

TLS1.0

TLS_PSK_SHA_3DES_EDE_CBC_SHA1

0x00 0x8B

TLS1.0

TLS_PSK_SHA_AES_128_CBC_SHA1

0x00 0x8C

TLS1.0

TLS_PSK_SHA_AES_256_CBC_SHA1

0x00 0x8D

TLS1.0

TLS_PSK_AES_128_CBC_SHA256

0x00 0xAE

TLS1.0

TLS_PSK_AES_128_GCM_SHA256

0x00 0xA8

TLS1.2

TLS_PSK_NULL_SHA256

0x00 0xB0

TLS1.0

TLS_DHE_PSK_SHA_ARCFOUR_SHA1

0x00 0x8E

TLS1.0

TLS_DHE_PSK_SHA_3DES_EDE_CBC_SHA1

0x00 0x8F

TLS1.0

TLS_DHE_PSK_SHA_AES_128_CBC_SHA1

0x00 0x90

TLS1.0

TLS_DHE_PSK_SHA_AES_256_CBC_SHA1

0x00 0x91

TLS1.0

TLS_DHE_PSK_AES_128_CBC_SHA256

0x00 0xB2

TLS1.0

TLS_DHE_PSK_AES_128_GCM_SHA256

0x00 0xAA

TLS1.2

TLS_DHE_PSK_NULL_SHA256

0x00 0xB4

TLS1.0

TLS_SRP_SHA_3DES_EDE_CBC_SHA1

0xC0 0x1A

TLS1.0

TLS_SRP_SHA_AES_128_CBC_SHA1

0xC0 0x1D

TLS1.0

TLS_SRP_SHA_AES_256_CBC_SHA1

0xC0 0x20

TLS1.0

TLS_SRP_SHA_DSS_3DES_EDE_CBC_SHA1

0xC0 0x1C

TLS1.0

TLS_SRP_SHA_RSA_3DES_EDE_CBC_SHA1

0xC0 0x1B

TLS1.0

TLS_SRP_SHA_DSS_AES_128_CBC_SHA1

0xC0 0x1F

TLS1.0

TLS_SRP_SHA_RSA_AES_128_CBC_SHA1

0xC0 0x1E

TLS1.0

TLS_SRP_SHA_DSS_AES_256_CBC_SHA1

0xC0 0x22

TLS1.0

TLS_SRP_SHA_RSA_AES_256_CBC_SHA1

0xC0 0x21

TLS1.0

TLS_DHE_DSS_ARCFOUR_SHA1

0x00 0x66

TLS1.0

TLS_DHE_DSS_3DES_EDE_CBC_SHA1

0x00 0x13

SSL3.0

TLS_DHE_DSS_AES_128_CBC_SHA1

0x00 0x32

SSL3.0

TLS_DHE_DSS_AES_256_CBC_SHA1

0x00 0x38

SSL3.0

TLS_DHE_DSS_CAMELLIA_128_CBC_SHA1

0x00 0x44

TLS1.0

TLS_DHE_DSS_CAMELLIA_256_CBC_SHA1

0x00 0x87

TLS1.0

TLS_DHE_DSS_AES_128_CBC_SHA256

0x00 0x40

TLS1.2

TLS_DHE_DSS_AES_256_CBC_SHA256

0x00 0x6A

TLS1.2

TLS_DHE_RSA_3DES_EDE_CBC_SHA1

0x00 0x16

SSL3.0

TLS_DHE_RSA_AES_128_CBC_SHA1

0x00 0x33

SSL3.0

TLS_DHE_RSA_AES_256_CBC_SHA1

0x00 0x39

SSL3.0

TLS_DHE_RSA_CAMELLIA_128_CBC_SHA1

0x00 0x45

TLS1.0

TLS_DHE_RSA_CAMELLIA_256_CBC_SHA1

0x00 0x88

TLS1.0

TLS_DHE_RSA_AES_128_CBC_SHA256

0x00 0x67

TLS1.2

TLS_DHE_RSA_AES_256_CBC_SHA256

0x00 0x6B

TLS1.2

TLS_RSA_NULL_MD5

0x00 0x01

SSL3.0

TLS_RSA_NULL_SHA1

0x00 0x02

SSL3.0

TLS_RSA_NULL_SHA256

0x00 0x3B

TLS1.2

TLS_RSA_EXPORT_ARCFOUR_40_MD5

0x00 0x03

SSL3.0

TLS_RSA_ARCFOUR_SHA1

0x00 0x05

SSL3.0

TLS_RSA_ARCFOUR_MD5

0x00 0x04

SSL3.0

TLS_RSA_3DES_EDE_CBC_SHA1

0x00 0x0A

SSL3.0

TLS_RSA_AES_128_CBC_SHA1

0x00 0x2F

SSL3.0

TLS_RSA_AES_256_CBC_SHA1

0x00 0x35

SSL3.0

TLS_RSA_CAMELLIA_128_CBC_SHA1

0x00 0x41

TLS1.0

TLS_RSA_CAMELLIA_256_CBC_SHA1

0x00 0x84

TLS1.0

TLS_RSA_AES_128_CBC_SHA256

0x00 0x3C

TLS1.2

TLS_RSA_AES_256_CBC_SHA256

0x00 0x3D

TLS1.2

TLS_RSA_AES_128_GCM_SHA256

0x00 0x9C

TLS1.2

TLS_DHE_RSA_AES_128_GCM_SHA256

0x00 0x9E

TLS1.2

TLS_DHE_DSS_AES_128_GCM_SHA256

0x00 0xA2

TLS1.2

TLS_DH_ANON_AES_128_GCM_SHA256

0x00 0xA6

TLS1.2

TLS_ECDH_ANON_NULL_SHA1

0xC0 0x15

TLS1.0

TLS_ECDH_ANON_3DES_EDE_CBC_SHA1

0xC0 0x17

TLS1.0

TLS_ECDH_ANON_AES_128_CBC_SHA1

0xC0 0x18

TLS1.0

TLS_ECDH_ANON_AES_256_CBC_SHA1

0xC0 0x19

TLS1.0

TLS_ECDHE_RSA_NULL_SHA1

0xC0 0x10

TLS1.0

TLS_ECDHE_RSA_3DES_EDE_CBC_SHA1

0xC0 0x12

TLS1.0

TLS_ECDHE_RSA_AES_128_CBC_SHA1

0xC0 0x13

TLS1.0

TLS_ECDHE_RSA_AES_256_CBC_SHA1

0xC0 0x14

TLS1.0

TLS_ECDHE_ECDSA_NULL_SHA1

0xC0 0x06

TLS1.0

TLS_ECDHE_ECDSA_3DES_EDE_CBC_SHA1

0xC0 0x08

TLS1.0

TLS_ECDHE_ECDSA_AES_128_CBC_SHA1

0xC0 0x09

TLS1.0

TLS_ECDHE_ECDSA_AES_256_CBC_SHA1

0xC0 0x0A

TLS1.0

TLS_ECDHE_ECDSA_AES_128_CBC_SHA256

0xC0 0x23

TLS1.2

TLS_ECDHE_RSA_AES_128_CBC_SHA256

0xC0 0x27

TLS1.2

TLS_ECDHE_ECDSA_AES_128_GCM_SHA256

0xC0 0x2B

TLS1.2

TLS_ECDHE_RSA_AES_128_GCM_SHA256

0xC0 0x2F

TLS1.2

TLS_ECDHE_PSK_3DES_EDE_CBC_SHA1

0xC0 0x34

TLS1.0

TLS_ECDHE_PSK_AES_128_CBC_SHA1

0xC0 0x35

TLS1.0

TLS_ECDHE_PSK_AES_256_CBC_SHA1

0xC0 0x36

TLS1.0

TLS_ECDHE_PSK_AES_128_CBC_SHA256

0xC0 0x37

TLS1.0

TLS_ECDHE_PSK_AES_256_CBC_SHA384

0xC0 0x38

TLS1.0

TLS_ECDHE_PSK_NULL_SHA256

0xC0 0x3A

TLS1.0

TLS_ECDHE_PSK_NULL_SHA384

0xC0 0x3B

TLS1.0

TLS_ECDHE_ECDSA_AES_256_GCM_SHA384

0xC0 0x2C

TLS1.2

TLS_ECDHE_RSA_AES_256_GCM_SHA384

0xC0 0x30

TLS1.2

TLS_ECDHE_ECDSA_AES_256_CBC_SHA384

0xC0 0x24

TLS1.2

TLS_PSK_WITH_AES_256_GCM_SHA384

0x00 0xA9

TLS1.2

TLS_DHE_PSK_WITH_AES_256_GCM_SHA384

0x00 0xAB

TLS1.2

Certificate types

X.509

OPENPGP

Protocols

SSL3.0

TLS1.0

TLS1.1

TLS1.2

DTLS1.0

Ciphers

AES-256-CBC

AES-192-CBC

AES-128-CBC

AES-128-GCM

AES-256-GCM

ARCFOUR-128

CAMELLIA-256-CBC

CAMELLIA-128-CBC

3DES-CBC

DES-CBC

ARCFOUR-40

RC2-40

MAC algorithms

SHA1

MD5

SHA256

SHA384

SHA512

SHA224

AEAD

Key exchange methods

ANON-DH

ANON-ECDH

RSA

RSA-EXPORT

DHE-RSA

ECDHE-RSA

ECDHE-ECDSA

DHE-DSS

SRP-DSS

SRP-RSA

SRP

PSK

DHE-PSK

ECDHE-PSK

Public key algorithms

RSA

DSA

EC

Public key signature algorithms

RSA-SHA1

RSA-SHA224

RSA-SHA256

RSA-SHA384

RSA-SHA512

RSA-RMD160

DSA-SHA1

DSA-SHA224

DSA-SHA256

RSA-MD5

RSA-MD2

ECDSA-SHA1

ECDSA-SHA224

ECDSA-SHA256

ECDSA-SHA384

ECDSA-SHA512

Elliptic curves

SECP192R1

SECP224R1

SECP256R1

SECP384R1

SECP521R1

Compression methods

DEFLATE

NULL

Appendix D. API reference

Core TLS API

The prototypes for the following functions lie in gnutls/gnutls.h.

gnutls_alert_get

Function: gnutls_alert_description_t gnutls_alert_get (gnutls_session_t session)

session: is a gnutls_session_t structure.

This function will return the last alert number received. This function should be called when GNUTLS_E_WARNING_ALERT_RECEIVED or GNUTLS_E_FATAL_ALERT_RECEIVED errors are returned by a gnutls function. The peer may send alerts if he encounters an error. If no alert has been received the returned value is undefined.

Returns: the last alert received, a gnutls_alert_description_t value.

gnutls_alert_get_name

Function: const char * gnutls_alert_get_name (gnutls_alert_description_t alert)

alert: is an alert number.

This function will return a string that describes the given alert number, or NULL . See gnutls_alert_get() .

Returns: string corresponding to gnutls_alert_description_t value.

gnutls_alert_get_strname

Function: const char * gnutls_alert_get_strname (gnutls_alert_description_t alert)

alert: is an alert number.

This function will return a string of the name of the alert.

Returns: string corresponding to gnutls_alert_description_t value.

Since: 3.0

gnutls_alert_send

Function: int gnutls_alert_send (gnutls_session_t session, gnutls_alert_level_t level, gnutls_alert_description_t desc)

session: is a gnutls_session_t structure.

level: is the level of the alert

desc: is the alert description

This function will send an alert to the peer in order to inform him of something important (eg. his Certificate could not be verified). If the alert level is Fatal then the peer is expected to close the connection, otherwise he may ignore the alert and continue.

The error code of the underlying record send function will be returned, so you may also receive GNUTLS_E_INTERRUPTED or GNUTLS_E_AGAIN as well.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise an error code is returned.

gnutls_alert_send_appropriate

Function: int gnutls_alert_send_appropriate (gnutls_session_t session, int err)

session: is a gnutls_session_t structure.

err: is an integer

Sends an alert to the peer depending on the error code returned by a gnutls function. This function will call gnutls_error_to_alert() to determine the appropriate alert to send.

This function may also return GNUTLS_E_AGAIN , or GNUTLS_E_INTERRUPTED .

If the return value is GNUTLS_E_INVALID_REQUEST , then no alert has been sent to the peer.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise an error code is returned.

gnutls_anon_allocate_client_credentials

Function: int gnutls_anon_allocate_client_credentials (gnutls_anon_client_credentials_t *                                          sc)

sc: is a pointer to a gnutls_anon_client_credentials_t structure.

This structure is complex enough to manipulate directly thus this helper function is provided in order to allocate it.

Returns: GNUTLS_E_SUCCESS on success, or an error code.

gnutls_anon_allocate_server_credentials

Function: int gnutls_anon_allocate_server_credentials (gnutls_anon_server_credentials_t *                                          sc)

sc: is a pointer to a gnutls_anon_server_credentials_t structure.

This structure is complex enough to manipulate directly thus this helper function is provided in order to allocate it.

Returns: GNUTLS_E_SUCCESS on success, or an error code.

gnutls_anon_free_client_credentials

Function: void gnutls_anon_free_client_credentials (gnutls_anon_client_credentials_t sc)

sc: is a gnutls_anon_client_credentials_t structure.

This structure is complex enough to manipulate directly thus this helper function is provided in order to free (deallocate) it.

gnutls_anon_free_server_credentials

Function: void gnutls_anon_free_server_credentials (gnutls_anon_server_credentials_t sc)

sc: is a gnutls_anon_server_credentials_t structure.

This structure is complex enough to manipulate directly thus this helper function is provided in order to free (deallocate) it.

gnutls_anon_set_params_function

Function: void gnutls_anon_set_params_function (gnutls_anon_server_credentials_t res, gnutls_params_function * func)

res: is a gnutls_anon_server_credentials_t structure

func: is the function to be called

This function will set a callback in order for the server to get the Diffie-Hellman or RSA parameters for anonymous authentication. The callback should return GNUTLS_E_SUCCESS (0) on success.

gnutls_anon_set_server_dh_params

Function: void gnutls_anon_set_server_dh_params (gnutls_anon_server_credentials_t res, gnutls_dh_params_t dh_params)

res: is a gnutls_anon_server_credentials_t structure

dh_params: is a structure that holds Diffie-Hellman parameters.

This function will set the Diffie-Hellman parameters for an anonymous server to use. These parameters will be used in Anonymous Diffie-Hellman cipher suites.

gnutls_anon_set_server_params_function

Function: void gnutls_anon_set_server_params_function (gnutls_anon_server_credentials_t res, gnutls_params_function * func)

res: is a gnutls_certificate_credentials_t structure

func: is the function to be called

This function will set a callback in order for the server to get the Diffie-Hellman parameters for anonymous authentication. The callback should return GNUTLS_E_SUCCESS (0) on success.

gnutls_auth_client_get_type

Function: gnutls_credentials_type_t gnutls_auth_client_get_type (gnutls_session_t session)

session: is a gnutls_session_t structure.

Returns the type of credentials that were used for client authentication. The returned information is to be used to distinguish the function used to access authentication data.

Returns: The type of credentials for the client authentication schema, a gnutls_credentials_type_t type.

gnutls_auth_get_type

Function: gnutls_credentials_type_t gnutls_auth_get_type (gnutls_session_t session)

session: is a gnutls_session_t structure.

Returns type of credentials for the current authentication schema. The returned information is to be used to distinguish the function used to access authentication data.

Eg. for CERTIFICATE ciphersuites (key exchange algorithms: GNUTLS_KX_RSA , GNUTLS_KX_DHE_RSA ), the same function are to be used to access the authentication data.

Returns: The type of credentials for the current authentication schema, a gnutls_credentials_type_t type.

gnutls_auth_server_get_type

Function: gnutls_credentials_type_t gnutls_auth_server_get_type (gnutls_session_t session)

session: is a gnutls_session_t structure.

Returns the type of credentials that were used for server authentication. The returned information is to be used to distinguish the function used to access authentication data.

Returns: The type of credentials for the server authentication schema, a gnutls_credentials_type_t type.

gnutls_bye

Function: int gnutls_bye (gnutls_session_t session, gnutls_close_request_t how)

session: is a gnutls_session_t structure.

how: is an integer

Terminates the current TLS/SSL connection. The connection should have been initiated using gnutls_handshake() . how should be one of GNUTLS_SHUT_RDWR , GNUTLS_SHUT_WR .

In case of GNUTLS_SHUT_RDWR the TLS session gets terminated and further receives and sends will be disallowed. If the return value is zero you may continue using the underlying transport layer. GNUTLS_SHUT_RDWR sends an alert containing a close request and waits for the peer to reply with the same message.

In case of GNUTLS_SHUT_WR the TLS session gets terminated and further sends will be disallowed. In order to reuse the connection you should wait for an EOF from the peer. GNUTLS_SHUT_WR sends an alert containing a close request.

Note that not all implementations will properly terminate a TLS connection. Some of them, usually for performance reasons, will terminate only the underlying transport layer, and thus not distinguishing between a malicious party prematurely terminating the connection and normal termination.

This function may also return GNUTLS_E_AGAIN or GNUTLS_E_INTERRUPTED ; cf. gnutls_record_get_direction() .

Returns: GNUTLS_E_SUCCESS on success, or an error code, see function documentation for entire semantics.

gnutls_certificate_activation_time_peers

Function: time_t gnutls_certificate_activation_time_peers (gnutls_session_t session)

session: is a gnutls session

This function will return the peer’s certificate activation time. This is the creation time for openpgp keys.

Returns: (time_t)-1 on error.

Deprecated: gnutls_certificate_verify_peers2() now verifies activation times.

gnutls_certificate_allocate_credentials

Function: int gnutls_certificate_allocate_credentials (gnutls_certificate_credentials_t *                                          res)

res: is a pointer to a gnutls_certificate_credentials_t structure.

This structure is complex enough to manipulate directly thus this helper function is provided in order to allocate it.

Returns: GNUTLS_E_SUCCESS on success, or an error code.

gnutls_certificate_client_get_request_status

Function: int gnutls_certificate_client_get_request_status (gnutls_session_t session)

session: is a gnutls session

Get whether client certificate is requested or not.

Returns: 0 if the peer (server) did not request client authentication or 1 otherwise, or a negative error code in case of error.

gnutls_certificate_expiration_time_peers

Function: time_t gnutls_certificate_expiration_time_peers (gnutls_session_t session)

session: is a gnutls session

This function will return the peer’s certificate expiration time.

Returns: (time_t)-1 on error.

Deprecated: gnutls_certificate_verify_peers2() now verifies expiration times.

gnutls_certificate_free_ca_names

Function: void gnutls_certificate_free_ca_names (gnutls_certificate_credentials_t sc)

sc: is a gnutls_certificate_credentials_t structure.

This function will delete all the CA name in the given credentials. Clients may call this to save some memory since in client side the CA names are not used. Servers might want to use this function if a large list of trusted CAs is present and sending the names of it would just consume bandwidth without providing information to client.

CA names are used by servers to advertise the CAs they support to clients.

gnutls_certificate_free_cas

Function: void gnutls_certificate_free_cas (gnutls_certificate_credentials_t sc)

sc: is a gnutls_certificate_credentials_t structure.

This function will delete all the CAs associated with the given credentials. Servers that do not use gnutls_certificate_verify_peers2() may call this to save some memory.

gnutls_certificate_free_credentials

Function: void gnutls_certificate_free_credentials (gnutls_certificate_credentials_t sc)

sc: is a gnutls_certificate_credentials_t structure.

This structure is complex enough to manipulate directly thus this helper function is provided in order to free (deallocate) it.

This function does not free any temporary parameters associated with this structure (ie RSA and DH parameters are not freed by this function).

gnutls_certificate_free_crls

Function: void gnutls_certificate_free_crls (gnutls_certificate_credentials_t sc)

sc: is a gnutls_certificate_credentials_t structure.

This function will delete all the CRLs associated with the given credentials.

gnutls_certificate_free_keys

Function: void gnutls_certificate_free_keys (gnutls_certificate_credentials_t sc)

sc: is a gnutls_certificate_credentials_t structure.

This function will delete all the keys and the certificates associated with the given credentials. This function must not be called when a TLS negotiation that uses the credentials is in progress.

gnutls_certificate_get_issuer

Function: int gnutls_certificate_get_issuer (gnutls_certificate_credentials_t sc, gnutls_x509_crt_t cert, gnutls_x509_crt_t* issuer, unsigned int flags)

sc: is a gnutls_certificate_credentials_t structure.

cert: is the certificate to find issuer for

issuer: Will hold the issuer if any. Should be treated as constant.

flags: Use zero.

This function will return the issuer of a given certificate.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 3.0

gnutls_certificate_get_ours

Function: const gnutls_datum_t * gnutls_certificate_get_ours (gnutls_session_t session)

session: is a gnutls session

Gets the certificate as sent to the peer in the last handshake. The certificate is in raw (DER) format. No certificate list is being returned. Only the first certificate.

Returns: a pointer to a gnutls_datum_t containing our certificates, or NULL in case of an error or if no certificate was used.

gnutls_certificate_get_peers

Function: const gnutls_datum_t * gnutls_certificate_get_peers (gnutls_session_t                               session, unsigned int * list_size)

session: is a gnutls session

list_size: is the length of the certificate list

Get the peer’s raw certificate (chain) as sent by the peer. These certificates are in raw format (DER encoded for X.509). In case of a X.509 then a certificate list may be present. The first certificate in the list is the peer’s certificate, following the issuer’s certificate, then the issuer’s issuer etc.

In case of OpenPGP keys a single key will be returned in raw format.

Returns: a pointer to a gnutls_datum_t containing our certificates, or NULL in case of an error or if no certificate was used.

gnutls_certificate_send_x509_rdn_sequence

Function: void gnutls_certificate_send_x509_rdn_sequence (gnutls_session_t session, int status)

session: is a pointer to a gnutls_session_t structure.

status: is 0 or 1

If status is non zero, this function will order gnutls not to send the rdnSequence in the certificate request message. That is the server will not advertise its trusted CAs to the peer. If status is zero then the default behaviour will take effect, which is to advertise the server’s trusted CAs.

This function has no effect in clients, and in authentication methods other than certificate with X.509 certificates.

gnutls_certificate_server_set_request

Function: void gnutls_certificate_server_set_request (gnutls_session_t session, gnutls_certificate_request_t req)

session: is a gnutls_session_t structure.

req: is one of GNUTLS_CERT_REQUEST, GNUTLS_CERT_REQUIRE

This function specifies if we (in case of a server) are going to send a certificate request message to the client. If req is GNUTLS_CERT_REQUIRE then the server will return an error if the peer does not provide a certificate. If you do not call this function then the client will not be asked to send a certificate.

gnutls_certificate_set_dh_params

Function: void gnutls_certificate_set_dh_params (gnutls_certificate_credentials_t res, gnutls_dh_params_t dh_params)

res: is a gnutls_certificate_credentials_t structure

dh_params: is a structure that holds Diffie-Hellman parameters.

This function will set the Diffie-Hellman parameters for a certificate server to use. These parameters will be used in Ephemeral Diffie-Hellman cipher suites. Note that only a pointer to the parameters are stored in the certificate handle, so if you deallocate the parameters before the certificate is deallocated, you must change the parameters stored in the certificate first.

gnutls_certificate_set_params_function

Function: void gnutls_certificate_set_params_function (gnutls_certificate_credentials_t res, gnutls_params_function * func)

res: is a gnutls_certificate_credentials_t structure

func: is the function to be called

This function will set a callback in order for the server to get the Diffie-Hellman or RSA parameters for certificate authentication. The callback should return GNUTLS_E_SUCCESS (0) on success.

gnutls_certificate_set_retrieve_function

Function: void gnutls_certificate_set_retrieve_function (gnutls_certificate_credentials_t cred, gnutls_certificate_retrieve_function * func)

cred: is a gnutls_certificate_credentials_t structure.

func: is the callback function

This function sets a callback to be called in order to retrieve the certificate to be used in the handshake. You are advised to use gnutls_certificate_set_retrieve_function2() because it is much more efficient in the processing it requires from gnutls.

The callback’s function prototype is: int (*callback)(gnutls_session_t, const gnutls_datum_t* req_ca_dn, int nreqs, const gnutls_pk_algorithm_t* pk_algos, int pk_algos_length, gnutls_retr2_st* st);

req_ca_cert is only used in X.509 certificates. Contains a list with the CA names that the server considers trusted. Normally we should send a certificate that is signed by one of these CAs. These names are DER encoded. To get a more meaningful value use the function gnutls_x509_rdn_get() .

pk_algos contains a list with server’s acceptable signature algorithms. The certificate returned should support the server’s given algorithms.

st should contain the certificates and private keys.

If the callback function is provided then gnutls will call it, in the handshake, after the certificate request message has been received.

In server side pk_algos and req_ca_dn are NULL.

The callback function should set the certificate list to be sent, and return 0 on success. If no certificate was selected then the number of certificates should be set to zero. The value (-1) indicates error and the handshake will be terminated.

Since: 3.0

gnutls_certificate_set_verify_flags

Function: void gnutls_certificate_set_verify_flags (gnutls_certificate_credentials_t                                      res, unsigned int flags)

res: is a gnutls_certificate_credentials_t structure

flags: are the flags

This function will set the flags to be used at verification of the certificates. Flags must be OR of the gnutls_certificate_verify_flags enumerations.

gnutls_certificate_set_verify_function

Function: void gnutls_certificate_set_verify_function (gnutls_certificate_credentials_t cred, gnutls_certificate_verify_function * func)

cred: is a gnutls_certificate_credentials_t structure.

func: is the callback function

This function sets a callback to be called when peer’s certificate has been received in order to verify it on receipt rather than doing after the handshake is completed.

The callback’s function prototype is: int (*callback)(gnutls_session_t);

If the callback function is provided then gnutls will call it, in the handshake, just after the certificate message has been received. To verify or obtain the certificate the gnutls_certificate_verify_peers2() , gnutls_certificate_type_get() , gnutls_certificate_get_peers() functions can be used.

The callback function should return 0 for the handshake to continue or non-zero to terminate.

Since: 2.10.0

gnutls_certificate_set_verify_limits

Function: void gnutls_certificate_set_verify_limits (gnutls_certificate_credentials_t res, unsigned int max_bits, unsigned int max_depth)

res: is a gnutls_certificate_credentials structure

max_bits: is the number of bits of an acceptable certificate (default 8200)

max_depth: is maximum depth of the verification of a certificate chain (default 5)

This function will set some upper limits for the default verification function, gnutls_certificate_verify_peers2() , to avoid denial of service attacks. You can set them to zero to disable limits.

gnutls_certificate_set_x509_crl

Function: int gnutls_certificate_set_x509_crl (gnutls_certificate_credentials_t res, gnutls_x509_crl_t * crl_list, int crl_list_size)

res: is a gnutls_certificate_credentials_t structure.

crl_list: is a list of trusted CRLs. They should have been verified before.

crl_list_size: holds the size of the crl_list

This function adds the trusted CRLs in order to verify client or server certificates. In case of a client this is not required to be called if the certificates are not verified using gnutls_certificate_verify_peers2() . This function may be called multiple times.

Returns: GNUTLS_E_SUCCESS (0) on success, or a negative error code.

Since: 2.4.0

gnutls_certificate_set_x509_crl_file

Function: int gnutls_certificate_set_x509_crl_file (gnutls_certificate_credentials_t res, const char * crlfile, gnutls_x509_crt_fmt_t type)

res: is a gnutls_certificate_credentials_t structure.

crlfile: is a file containing the list of verified CRLs (DER or PEM list)

type: is PEM or DER

This function adds the trusted CRLs in order to verify client or server certificates. In case of a client this is not required to be called if the certificates are not verified using gnutls_certificate_verify_peers2() . This function may be called multiple times.

Returns: number of CRLs processed or a negative error code on error.

gnutls_certificate_set_x509_crl_mem

Function: int gnutls_certificate_set_x509_crl_mem (gnutls_certificate_credentials_t res, const gnutls_datum_t * CRL, gnutls_x509_crt_fmt_t type)

res: is a gnutls_certificate_credentials_t structure.

CRL: is a list of trusted CRLs. They should have been verified before.

type: is DER or PEM

This function adds the trusted CRLs in order to verify client or server certificates. In case of a client this is not required to be called if the certificates are not verified using gnutls_certificate_verify_peers2() . This function may be called multiple times.

Returns: number of CRLs processed, or a negative error code on error.

gnutls_certificate_set_x509_key

Function: int gnutls_certificate_set_x509_key (gnutls_certificate_credentials_t res, gnutls_x509_crt_t * cert_list, int cert_list_size, gnutls_x509_privkey_t key)

res: is a gnutls_certificate_credentials_t structure.

cert_list: contains a certificate list (path) for the specified private key

cert_list_size: holds the size of the certificate list

key: is a gnutls_x509_privkey_t key

This function sets a certificate/private key pair in the gnutls_certificate_credentials_t structure. This function may be called more than once, in case multiple keys/certificates exist for the server. For clients that wants to send more than its own end entity certificate (e.g., also an intermediate CA cert) then put the certificate chain in cert_list .

Returns: GNUTLS_E_SUCCESS (0) on success, or a negative error code.

Since: 2.4.0

gnutls_certificate_set_x509_key_file

Function: int gnutls_certificate_set_x509_key_file (gnutls_certificate_credentials_t res, const char * certfile, const char * keyfile, gnutls_x509_crt_fmt_t type)

res: is a gnutls_certificate_credentials_t structure.

certfile: is a file that containing the certificate list (path) for the specified private key, in PKCS7 format, or a list of certificates

keyfile: is a file that contains the private key

type: is PEM or DER

This function sets a certificate/private key pair in the gnutls_certificate_credentials_t structure. This function may be called more than once, in case multiple keys/certificates exist for the server. For clients that need to send more than its own end entity certificate, e.g., also an intermediate CA cert, then the certfile must contain the ordered certificate chain.

This function can also accept PKCS 11 URLs at keyfile and certfile . In that case it will import the private key and certificate indicated by the URLs.

Returns: GNUTLS_E_SUCCESS (0) on success, or a negative error code.

gnutls_certificate_set_x509_key_mem

Function: int gnutls_certificate_set_x509_key_mem (gnutls_certificate_credentials_t res, const gnutls_datum_t * cert, const gnutls_datum_t * key, gnutls_x509_crt_fmt_t type)

res: is a gnutls_certificate_credentials_t structure.

cert: contains a certificate list (path) for the specified private key

key: is the private key, or NULL

type: is PEM or DER

This function sets a certificate/private key pair in the gnutls_certificate_credentials_t structure. This function may be called more than once, in case multiple keys/certificates exist for the server.

Note that the keyUsage (2.5.29.15) PKIX extension in X.509 certificates is supported. This means that certificates intended for signing cannot be used for ciphersuites that require encryption.

If the certificate and the private key are given in PEM encoding then the strings that hold their values must be null terminated.

The key may be NULL if you are using a sign callback, see gnutls_sign_callback_set() .

Returns: GNUTLS_E_SUCCESS (0) on success, or a negative error code.

gnutls_certificate_set_x509_simple_pkcs12_file

Function: int gnutls_certificate_set_x509_simple_pkcs12_file (gnutls_certificate_credentials_t res, const char * pkcs12file, gnutls_x509_crt_fmt_t type, const char * password)

res: is a gnutls_certificate_credentials_t structure.

pkcs12file: filename of file containing PKCS12 blob.

type: is PEM or DER of the pkcs12file .

password: optional password used to decrypt PKCS12 file, bags and keys.

This function sets a certificate/private key pair and/or a CRL in the gnutls_certificate_credentials_t structure. This function may be called more than once (in case multiple keys/certificates exist for the server).

PKCS12 files with a MAC, encrypted bags and PKCS 8 private keys are supported. However, only password based security, and the same password for all operations, are supported.

PKCS12 file may contain many keys and/or certificates, and there is no way to identify which key/certificate pair you want. You should make sure the PKCS12 file only contain one key/certificate pair and/or one CRL.

It is believed that the limitations of this function is acceptable for most usage, and that any more flexibility would introduce complexity that would make it harder to use this functionality at all.

Returns: GNUTLS_E_SUCCESS (0) on success, or a negative error code.

gnutls_certificate_set_x509_simple_pkcs12_mem

Function: int gnutls_certificate_set_x509_simple_pkcs12_mem (gnutls_certificate_credentials_t res, const gnutls_datum_t * p12blob, gnutls_x509_crt_fmt_t type, const char * password)

res: is a gnutls_certificate_credentials_t structure.

p12blob: the PKCS12 blob.

type: is PEM or DER of the pkcs12file .

password: optional password used to decrypt PKCS12 file, bags and keys.

This function sets a certificate/private key pair and/or a CRL in the gnutls_certificate_credentials_t structure. This function may be called more than once (in case multiple keys/certificates exist for the server).

MAC: ed PKCS12 files are supported. Encrypted PKCS12 bags are supported. Encrypted PKCS8 private keys are supported. However, only password based security, and the same password for all operations, are supported.

PKCS12 file may contain many keys and/or certificates, and there is no way to identify which key/certificate pair you want. You should make sure the PKCS12 file only contain one key/certificate pair and/or one CRL.

It is believed that the limitations of this function is acceptable for most usage, and that any more flexibility would introduce complexity that would make it harder to use this functionality at all.

Returns: GNUTLS_E_SUCCESS (0) on success, or a negative error code.

Since: 2.8.0

gnutls_certificate_set_x509_trust

Function: int gnutls_certificate_set_x509_trust (gnutls_certificate_credentials_t res, gnutls_x509_crt_t * ca_list, int ca_list_size)

res: is a gnutls_certificate_credentials_t structure.

ca_list: is a list of trusted CAs

ca_list_size: holds the size of the CA list

This function adds the trusted CAs in order to verify client or server certificates. In case of a client this is not required to be called if the certificates are not verified using gnutls_certificate_verify_peers2() . This function may be called multiple times.

In case of a server the CAs set here will be sent to the client if a certificate request is sent. This can be disabled using gnutls_certificate_send_x509_rdn_sequence() .

Returns: the number of certificates processed or a negative error code on error.

Since: 2.4.0

gnutls_certificate_set_x509_trust_file

Function: int gnutls_certificate_set_x509_trust_file (gnutls_certificate_credentials_t cred, const char * cafile, gnutls_x509_crt_fmt_t type)

cred: is a gnutls_certificate_credentials_t structure.

cafile: is a file containing the list of trusted CAs (DER or PEM list)

type: is PEM or DER

This function adds the trusted CAs in order to verify client or server certificates. In case of a client this is not required to be called if the certificates are not verified using gnutls_certificate_verify_peers2() . This function may be called multiple times.

In case of a server the names of the CAs set here will be sent to the client if a certificate request is sent. This can be disabled using gnutls_certificate_send_x509_rdn_sequence() .

This function can also accept PKCS 11 URLs. In that case it will import all certificates that are marked as trusted.

Returns: number of certificates processed, or a negative error code on error.

gnutls_certificate_set_x509_trust_mem

Function: int gnutls_certificate_set_x509_trust_mem (gnutls_certificate_credentials_t res, const gnutls_datum_t * ca, gnutls_x509_crt_fmt_t type)

res: is a gnutls_certificate_credentials_t structure.

ca: is a list of trusted CAs or a DER certificate

type: is DER or PEM

This function adds the trusted CAs in order to verify client or server certificates. In case of a client this is not required to be called if the certificates are not verified using gnutls_certificate_verify_peers2() . This function may be called multiple times.

In case of a server the CAs set here will be sent to the client if a certificate request is sent. This can be disabled using gnutls_certificate_send_x509_rdn_sequence() .

Returns: the number of certificates processed or a negative error code on error.

gnutls_certificate_type_get

Function: gnutls_certificate_type_t gnutls_certificate_type_get (gnutls_session_t session)

session: is a gnutls_session_t structure.

The certificate type is by default X.509, unless it is negotiated as a TLS extension.

Returns: the currently used gnutls_certificate_type_t certificate type.

gnutls_certificate_type_get_id

Function: gnutls_certificate_type_t gnutls_certificate_type_get_id (const char * name)

name: is a certificate type name

The names are compared in a case insensitive way.

Returns: a gnutls_certificate_type_t for the specified in a string certificate type, or GNUTLS_CRT_UNKNOWN on error.

gnutls_certificate_type_get_name

Function: const char * gnutls_certificate_type_get_name (gnutls_certificate_type_t type)

type: is a certificate type

Convert a gnutls_certificate_type_t type to a string.

Returns: a string that contains the name of the specified certificate type, or NULL in case of unknown types.

gnutls_certificate_type_list

Function: const gnutls_certificate_type_t * gnutls_certificate_type_list ( void)

Get a list of certificate types. Note that to be able to use OpenPGP certificates, you must link to libgnutls-extra and call gnutls_global_init_extra() .

Returns: a (0)-terminated list of gnutls_certificate_type_t integers indicating the available certificate types.

gnutls_certificate_verify_peers2

Function: int gnutls_certificate_verify_peers2 (gnutls_session_t session, unsigned int * status)

session: is a gnutls session

status: is the output of the verification

This function will try to verify the peer’s certificate and return its status (trusted, invalid etc.). The value of status should be one or more of the gnutls_certificate_status_t enumerated elements bitwise or’d. To avoid denial of service attacks some default upper limits regarding the certificate key size and chain size are set. To override them use gnutls_certificate_set_verify_limits() .

Note that you must also check the peer’s name in order to check if the verified certificate belongs to the actual peer.

This function uses gnutls_x509_crt_list_verify() with the CAs in the credentials as trusted CAs.

Returns: a negative error code on error and GNUTLS_E_SUCCESS (0) on success.

gnutls_check_version

Function: const char * gnutls_check_version (const char * req_version)

req_version: version string to compare with, or NULL .

Check GnuTLS Library version.

See GNUTLS_VERSION for a suitable req_version string.

Returns: Check that the version of the library is at minimum the one given as a string in req_version and return the actual version string of the library; return NULL if the condition is not met. If NULL is passed to this function no check is done and only the version string is returned.

gnutls_cipher_get

Function: gnutls_cipher_algorithm_t gnutls_cipher_get (gnutls_session_t session)

session: is a gnutls_session_t structure.

Get currently used cipher.

Returns: the currently used cipher, a gnutls_cipher_algorithm_t type.

gnutls_cipher_get_id

Function: gnutls_cipher_algorithm_t gnutls_cipher_get_id (const char * name)

name: is a cipher algorithm name

The names are compared in a case insensitive way.

Returns: return a gnutls_cipher_algorithm_t value corresponding to the specified cipher, or GNUTLS_CIPHER_UNKNOWN on error.

gnutls_cipher_get_key_size

Function: size_t gnutls_cipher_get_key_size (gnutls_cipher_algorithm_t algorithm)

algorithm: is an encryption algorithm

Get key size for cipher.

Returns: length (in bytes) of the given cipher’s key size, or 0 if the given cipher is invalid.

gnutls_cipher_get_name

Function: const char * gnutls_cipher_get_name (gnutls_cipher_algorithm_t algorithm)

algorithm: is an encryption algorithm

Convert a gnutls_cipher_algorithm_t type to a string.

Returns: a pointer to a string that contains the name of the specified cipher, or NULL .

gnutls_cipher_list

Function: const gnutls_cipher_algorithm_t * gnutls_cipher_list ( void)

Get a list of supported cipher algorithms. Note that not necessarily all ciphers are supported as TLS cipher suites. For example, DES is not supported as a cipher suite, but is supported for other purposes (e.g., PKCS8 or similar).

This function is not thread safe.

Returns: a (0)-terminated list of gnutls_cipher_algorithm_t integers indicating the available ciphers.

gnutls_cipher_suite_get_name

Function: const char * gnutls_cipher_suite_get_name (gnutls_kx_algorithm_t kx_algorithm, gnutls_cipher_algorithm_t cipher_algorithm, gnutls_mac_algorithm_t mac_algorithm)

kx_algorithm: is a Key exchange algorithm

cipher_algorithm: is a cipher algorithm

mac_algorithm: is a MAC algorithm

Note that the full cipher suite name must be prepended by TLS or SSL depending of the protocol in use.

Returns: a string that contains the name of a TLS cipher suite, specified by the given algorithms, or NULL .

gnutls_cipher_suite_info

Function: const char * gnutls_cipher_suite_info (size_t idx, unsigned char * cs_id, gnutls_kx_algorithm_t * kx, gnutls_cipher_algorithm_t * cipher, gnutls_mac_algorithm_t * mac, gnutls_protocol_t * min_version)

idx: index of cipher suite to get information about, starts on 0.

cs_id: output buffer with room for 2 bytes, indicating cipher suite value

kx: output variable indicating key exchange algorithm, or NULL .

cipher: output variable indicating cipher, or NULL .

mac: output variable indicating MAC algorithm, or NULL .

min_version: output variable indicating TLS protocol version, or NULL .

Get information about supported cipher suites. Use the function iteratively to get information about all supported cipher suites. Call with idx=0 to get information about first cipher suite, then idx=1 and so on until the function returns NULL.

Returns: the name of idx cipher suite, and set the information about the cipher suite in the output variables. If idx is out of bounds, NULL is returned.

gnutls_compression_get

Function: gnutls_compression_method_t gnutls_compression_get (gnutls_session_t session)

session: is a gnutls_session_t structure.

Get currently used compression algorithm.

Returns: the currently used compression method, a gnutls_compression_method_t value.

gnutls_compression_get_id

Function: gnutls_compression_method_t gnutls_compression_get_id (const char * name)

name: is a compression method name

The names are compared in a case insensitive way.

Returns: an id of the specified in a string compression method, or GNUTLS_COMP_UNKNOWN on error.

gnutls_compression_get_name

Function: const char * gnutls_compression_get_name (gnutls_compression_method_t algorithm)

algorithm: is a Compression algorithm

Convert a gnutls_compression_method_t value to a string.

Returns: a pointer to a string that contains the name of the specified compression algorithm, or NULL .

gnutls_compression_list

Function: const gnutls_compression_method_t * gnutls_compression_list ( void)

Get a list of compression methods.

Returns: a zero-terminated list of gnutls_compression_method_t integers indicating the available compression methods.

gnutls_credentials_clear

Function: void gnutls_credentials_clear (gnutls_session_t session)

session: is a gnutls_session_t structure.

Clears all the credentials previously set in this session.

gnutls_credentials_set

Function: int gnutls_credentials_set (gnutls_session_t session, gnutls_credentials_type_t type, void * cred)

session: is a gnutls_session_t structure.

type: is the type of the credentials

cred: is a pointer to a structure.

Sets the needed credentials for the specified type. Eg username, password - or public and private keys etc. The cred parameter is a structure that depends on the specified type and on the current session (client or server).

In order to minimize memory usage, and share credentials between several threads gnutls keeps a pointer to cred, and not the whole cred structure. Thus you will have to keep the structure allocated until you call gnutls_deinit() .

For GNUTLS_CRD_ANON , cred should be gnutls_anon_client_credentials_t in case of a client. In case of a server it should be gnutls_anon_server_credentials_t .

For GNUTLS_CRD_SRP , cred should be gnutls_srp_client_credentials_t in case of a client, and gnutls_srp_server_credentials_t , in case of a server.

For GNUTLS_CRD_CERTIFICATE , cred should be gnutls_certificate_credentials_t .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

gnutls_db_check_entry

Function: int gnutls_db_check_entry (gnutls_session_t session, gnutls_datum_t session_entry)

session: is a gnutls_session_t structure.

session_entry: is the session data (not key)

Check if database entry has expired. This function is to be used when you want to clear unnecessary sessions which occupy space in your backend.

Returns: Returns GNUTLS_E_EXPIRED , if the database entry has expired or 0 otherwise.

gnutls_db_get_ptr

Function: void * gnutls_db_get_ptr (gnutls_session_t session)

session: is a gnutls_session_t structure.

Get db function pointer.

Returns: the pointer that will be sent to db store, retrieve and delete functions, as the first argument.

gnutls_db_remove_session

Function: void gnutls_db_remove_session (gnutls_session_t session)

session: is a gnutls_session_t structure.

This function will remove the current session data from the session database. This will prevent future handshakes reusing these session data. This function should be called if a session was terminated abnormally, and before gnutls_deinit() is called.

Normally gnutls_deinit() will remove abnormally terminated sessions.

gnutls_db_set_cache_expiration

Function: void gnutls_db_set_cache_expiration (gnutls_session_t session, int seconds)

session: is a gnutls_session_t structure.

seconds: is the number of seconds.

Set the expiration time for resumed sessions. The default is 3600 (one hour) at the time of this writing.

gnutls_db_set_ptr

Function: void gnutls_db_set_ptr (gnutls_session_t session, void * ptr)

session: is a gnutls_session_t structure.

ptr: is the pointer

Sets the pointer that will be provided to db store, retrieve and delete functions, as the first argument.

gnutls_db_set_remove_function

Function: void gnutls_db_set_remove_function (gnutls_session_t session, gnutls_db_remove_func rem_func)

session: is a gnutls_session_t structure.

rem_func: is the function.

Sets the function that will be used to remove data from the resumed sessions database. This function must return 0 on success.

The first argument to rem_func will be null unless gnutls_db_set_ptr() has been called.

gnutls_db_set_retrieve_function

Function: void gnutls_db_set_retrieve_function (gnutls_session_t session, gnutls_db_retr_func retr_func)

session: is a gnutls_session_t structure.

retr_func: is the function.

Sets the function that will be used to retrieve data from the resumed sessions database. This function must return a gnutls_datum_t containing the data on success, or a gnutls_datum_t containing null and 0 on failure.

The datum’s data must be allocated using the function gnutls_malloc() .

The first argument to retr_func will be null unless gnutls_db_set_ptr() has been called.

gnutls_db_set_store_function

Function: void gnutls_db_set_store_function (gnutls_session_t session, gnutls_db_store_func store_func)

session: is a gnutls_session_t structure.

store_func: is the function

Sets the function that will be used to store data in the resumed sessions database. This function must return 0 on success.

The first argument to store_func will be null unless gnutls_db_set_ptr() has been called.

gnutls_deinit

Function: void gnutls_deinit (gnutls_session_t session)

session: is a gnutls_session_t structure.

This function clears all buffers associated with the session . This function will also remove session data from the session database if the session was terminated abnormally.

gnutls_dh_get_group

Function: int gnutls_dh_get_group (gnutls_session_t session, gnutls_datum_t * raw_gen, gnutls_datum_t * raw_prime)

session: is a gnutls session

raw_gen: will hold the generator.

raw_prime: will hold the prime.

This function will return the group parameters used in the last Diffie-Hellman key exchange with the peer. These are the prime and the generator used. This function should be used for both anonymous and ephemeral Diffie-Hellman. The output parameters must be freed with gnutls_free() .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise an error code is returned.

gnutls_dh_get_peers_public_bits

Function: int gnutls_dh_get_peers_public_bits (gnutls_session_t session)

session: is a gnutls session

Get the Diffie-Hellman public key bit size. Can be used for both anonymous and ephemeral Diffie-Hellman.

Returns: The public key bit size used in the last Diffie-Hellman key exchange with the peer, or a negative error code in case of error.

gnutls_dh_get_prime_bits

Function: int gnutls_dh_get_prime_bits (gnutls_session_t session)

session: is a gnutls session

This function will return the bits of the prime used in the last Diffie-Hellman key exchange with the peer. Should be used for both anonymous and ephemeral Diffie-Hellman. Note that some ciphers, like RSA and DSA without DHE, do not use a Diffie-Hellman key exchange, and then this function will return 0.

Returns: The Diffie-Hellman bit strength is returned, or 0 if no Diffie-Hellman key exchange was done, or a negative error code on failure.

gnutls_dh_get_pubkey

Function: int gnutls_dh_get_pubkey (gnutls_session_t session, gnutls_datum_t * raw_key)

session: is a gnutls session

raw_key: will hold the public key.

This function will return the peer’s public key used in the last Diffie-Hellman key exchange. This function should be used for both anonymous and ephemeral Diffie-Hellman. The output parameters must be freed with gnutls_free() .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise an error code is returned.

gnutls_dh_get_secret_bits

Function: int gnutls_dh_get_secret_bits (gnutls_session_t session)

session: is a gnutls session

This function will return the bits used in the last Diffie-Hellman key exchange with the peer. Should be used for both anonymous and ephemeral Diffie-Hellman.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise an error code is returned.

gnutls_dh_params_cpy

Function: int gnutls_dh_params_cpy (gnutls_dh_params_t dst, gnutls_dh_params_t src)

dst: Is the destination structure, which should be initialized.

src: Is the source structure

This function will copy the DH parameters structure from source to destination.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

gnutls_dh_params_deinit

Function: void gnutls_dh_params_deinit (gnutls_dh_params_t dh_params)

dh_params: Is a structure that holds the prime numbers

This function will deinitialize the DH parameters structure.

gnutls_dh_params_export_pkcs3

Function: int gnutls_dh_params_export_pkcs3 (gnutls_dh_params_t params, gnutls_x509_crt_fmt_t format, unsigned char * params_data, size_t * params_data_size)

params: Holds the DH parameters

format: the format of output params. One of PEM or DER.

params_data: will contain a PKCS3 DHParams structure PEM or DER encoded

params_data_size: holds the size of params_data (and will be replaced by the actual size of parameters)

This function will export the given dh parameters to a PKCS3 DHParams structure. This is the format generated by "openssl dhparam" tool. If the buffer provided is not long enough to hold the output, then GNUTLS_E_SHORT_MEMORY_BUFFER will be returned.

If the structure is PEM encoded, it will have a header of "BEGIN DH PARAMETERS".

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

gnutls_dh_params_export_raw

Function: int gnutls_dh_params_export_raw (gnutls_dh_params_t params, gnutls_datum_t * prime, gnutls_datum_t * generator, unsigned int * bits)

params: Holds the DH parameters

prime: will hold the new prime

generator: will hold the new generator

bits: if non null will hold the secret key’s number of bits

This function will export the pair of prime and generator for use in the Diffie-Hellman key exchange. The new parameters will be allocated using gnutls_malloc() and will be stored in the appropriate datum.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

gnutls_dh_params_generate2

Function: int gnutls_dh_params_generate2 (gnutls_dh_params_t params, unsigned int bits)

params: Is the structure that the DH parameters will be stored

bits: is the prime’s number of bits

This function will generate a new pair of prime and generator for use in the Diffie-Hellman key exchange. The new parameters will be allocated using gnutls_malloc() and will be stored in the appropriate datum. This function is normally slow.

Do not set the number of bits directly, use gnutls_sec_param_to_pk_bits() to get bits for GNUTLS_PK_DSA . Also note that the DH parameters are only useful to servers. Since clients use the parameters sent by the server, it’s of no use to call this in client side.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

gnutls_dh_params_import_pkcs3

Function: int gnutls_dh_params_import_pkcs3 (gnutls_dh_params_t params, const gnutls_datum_t * pkcs3_params, gnutls_x509_crt_fmt_t format)

params: A structure where the parameters will be copied to

pkcs3_params: should contain a PKCS3 DHParams structure PEM or DER encoded

format: the format of params. PEM or DER.

This function will extract the DHParams found in a PKCS3 formatted structure. This is the format generated by "openssl dhparam" tool.

If the structure is PEM encoded, it should have a header of "BEGIN DH PARAMETERS".

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

gnutls_dh_params_import_raw

Function: int gnutls_dh_params_import_raw (gnutls_dh_params_t dh_params, const gnutls_datum_t * prime, const gnutls_datum_t * generator)

dh_params: Is a structure that will hold the prime numbers

prime: holds the new prime

generator: holds the new generator

This function will replace the pair of prime and generator for use in the Diffie-Hellman key exchange. The new parameters should be stored in the appropriate gnutls_datum.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

gnutls_dh_params_init

Function: int gnutls_dh_params_init (gnutls_dh_params_t * dh_params)

dh_params: Is a structure that will hold the prime numbers

This function will initialize the DH parameters structure.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

gnutls_dh_set_prime_bits

Function: void gnutls_dh_set_prime_bits (gnutls_session_t session, unsigned int bits)

session: is a gnutls_session_t structure.

bits: is the number of bits

This function sets the number of bits, for use in a Diffie-Hellman key exchange. This is used both in DH ephemeral and DH anonymous cipher suites. This will set the minimum size of the prime that will be used for the handshake.

In the client side it sets the minimum accepted number of bits. If a server sends a prime with less bits than that GNUTLS_E_DH_PRIME_UNACCEPTABLE will be returned by the handshake.

This function has no effect in server side.

gnutls_ecc_curve_get

Function: gnutls_ecc_curve_t gnutls_ecc_curve_get (gnutls_session_t session)

session: is a gnutls_session_t structure.

Returns the currently used elliptic curve. Only valid when using an elliptic curve ciphersuite.

Returns: the currently used curve, a gnutls_ecc_curve_t type.

Since: 3.0

gnutls_ecc_curve_get_name

Function: const char * gnutls_ecc_curve_get_name (gnutls_ecc_curve_t curve)

curve: is an ECC curve

Convert a gnutls_ecc_curve_t value to a string.

Returns: a string that contains the name of the specified curve or NULL .

Since: 3.0

gnutls_ecc_curve_get_size

Function: int gnutls_ecc_curve_get_size (gnutls_ecc_curve_t curve)

curve: is an ECC curve

Returns the size in bytes of the curve.

Returns: a the size or (0).

Since: 3.0

gnutls_ecc_curve_list

Function: const gnutls_ecc_curve_t * gnutls_ecc_curve_list ( void)

Get the list of supported elliptic curves.

This function is not thread safe.

Returns: Return a (0)-terminated list of gnutls_ecc_curve_t integers indicating the available curves.

gnutls_error_is_fatal

Function: int gnutls_error_is_fatal (int error)

error: is a GnuTLS error code, a negative error code

If a GnuTLS function returns a negative error code you may feed that value to this function to see if the error condition is fatal. Note that you may also want to check the error code manually, since some non-fatal errors to the protocol (such as a warning alert or a rehandshake request) may be fatal for your program.

This function is only useful if you are dealing with errors from the record layer or the handshake layer.

Returns: 1 if the error code is fatal, for positive error values, 0 is returned. For unknown error values, -1 is returned.

gnutls_error_to_alert

Function: int gnutls_error_to_alert (int err, int * level)

err: is a negative integer

level: the alert level will be stored there

Get an alert depending on the error code returned by a gnutls function. All alerts sent by this function should be considered fatal. The only exception is when err is GNUTLS_E_REHANDSHAKE , where a warning alert should be sent to the peer indicating that no renegotiation will be performed.

If there is no mapping to a valid alert the alert to indicate internal error is returned.

Returns: the alert code to use for a particular error code.

gnutls_fingerprint

Function: int gnutls_fingerprint (gnutls_digest_algorithm_t algo, const gnutls_datum_t * data, void * result, size_t * result_size)

algo: is a digest algorithm

data: is the data

result: is the place where the result will be copied (may be null).

result_size: should hold the size of the result. The actual size of the returned result will also be copied there.

This function will calculate a fingerprint (actually a hash), of the given data. The result is not printable data. You should convert it to hex, or to something else printable.

This is the usual way to calculate a fingerprint of an X.509 DER encoded certificate. Note however that the fingerprint of an OpenPGP is not just a hash and cannot be calculated with this function.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise an error code is returned.

gnutls_global_deinit

Function: void gnutls_global_deinit ( void)

This function deinitializes the global data, that were initialized using gnutls_global_init() .

Note! This function is not thread safe. See the discussion for gnutls_global_init() for more information.

gnutls_global_init

Function: int gnutls_global_init ( void)

This function initializes the global data to defaults. In order to free resources you may call gnutls_global_deinit() when gnutls usage is no longer needed.

Note that this function will also initialize the underlying crypto backend, if it has not been initialized before.

This function increments a global counter, so that gnutls_global_deinit() only releases resources when it has been called as many times as gnutls_global_init() . This is useful when GnuTLS is used by more than one library in an application. This function can be called many times, but will only do something the first time.

Note! This function is not thread safe. If two threads call this function simultaneously, they can cause a race between checking the global counter and incrementing it, causing both threads to execute the library initialization code. That would lead to a memory leak. To handle this, your application could invoke this function after aquiring a thread mutex. To ignore the potential memory leak is also an option.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

gnutls_global_set_audit_log_function

Function: void gnutls_global_set_audit_log_function (gnutls_audit_log_func log_func)

log_func: it is the audit log function

This is the function where you set the logging function gnutls is going to use. This is different from gnutls_global_set_log_function() because it will report the session of the event if any. Note that that session might be null if there is no corresponding TLS session.

gnutls_audit_log_func is of the form, void (*gnutls_audit_log_func)( gnutls_session_t, int level, const char*);

Since: 3.0

gnutls_global_set_log_function

Function: void gnutls_global_set_log_function (gnutls_log_func log_func)

log_func: it’s a log function

This is the function where you set the logging function gnutls is going to use. This function only accepts a character array. Normally you may not use this function since it is only used for debugging purposes.

gnutls_log_func is of the form, void (*gnutls_log_func)( int level, const char*);

gnutls_global_set_log_level

Function: void gnutls_global_set_log_level (int level)

level: it’s an integer from 0 to 9.

This is the function that allows you to set the log level. The level is an integer between 0 and 9. Higher values mean more verbosity. The default value is 0. Larger values should only be used with care, since they may reveal sensitive information.

Use a log level over 10 to enable all debugging options.

gnutls_global_set_mem_functions

Function: void gnutls_global_set_mem_functions (gnutls_alloc_function alloc_func, gnutls_alloc_function secure_alloc_func, gnutls_is_secure_function is_secure_func, gnutls_realloc_function realloc_func, gnutls_free_function free_func)

alloc_func: it’s the default memory allocation function. Like malloc() .

secure_alloc_func: This is the memory allocation function that will be used for sensitive data.

is_secure_func: a function that returns 0 if the memory given is not secure. May be NULL.

realloc_func: A realloc function

free_func: The function that frees allocated data. Must accept a NULL pointer.

This is the function where you set the memory allocation functions gnutls is going to use. By default the libc’s allocation functions (malloc() , free() ), are used by gnutls, to allocate both sensitive and not sensitive data. This function is provided to set the memory allocation functions to something other than the defaults

This function must be called before gnutls_global_init() is called. This function is not thread safe.

gnutls_global_set_mutex

Function: void gnutls_global_set_mutex (mutex_init_func init, mutex_deinit_func deinit, mutex_lock_func lock, mutex_unlock_func unlock)

init: mutex initialization function

deinit: mutex deinitialization function

lock: mutex locking function

unlock: mutex unlocking function

With this function you are allowed to override the default mutex locks used in some parts of gnutls and dependent libraries. This function should be used if you have complete control of your program and libraries. Do not call this function from a library. Instead only initialize gnutls and the default OS mutex locks will be used.

This function must be called before gnutls_global_init() .

Since: 2.12.0

gnutls_global_set_time_function

Function: void gnutls_global_set_time_function (gnutls_time_func time_func)

time_func: it’s the system time function, a gnutls_time_func() callback.

This is the function where you can override the default system time function. The application provided function should behave the same as the standard function.

Since: 2.12.0

gnutls_handshake

Function: int gnutls_handshake (gnutls_session_t session)

session: is a gnutls_session_t structure.

This function does the handshake of the TLS/SSL protocol, and initializes the TLS connection.

This function will fail if any problem is encountered, and will return a negative error code. In case of a client, if the client has asked to resume a session, but the server couldn’t, then a full handshake will be performed.

The non-fatal errors such as GNUTLS_E_AGAIN and GNUTLS_E_INTERRUPTED interrupt the handshake procedure, which should be resumed later. Call this function again, until it returns 0; cf. gnutls_record_get_direction() and gnutls_error_is_fatal() .

If this function is called by a server after a rehandshake request then GNUTLS_E_GOT_APPLICATION_DATA or GNUTLS_E_WARNING_ALERT_RECEIVED may be returned. Note that these are non fatal errors, only in the specific case of a rehandshake. Their meaning is that the client rejected the rehandshake request or in the case of GNUTLS_E_GOT_APPLICATION_DATA it might also mean that some data were pending.

Returns: GNUTLS_E_SUCCESS on success, otherwise a negative error code.

gnutls_handshake_get_last_in

Function: gnutls_handshake_description_t gnutls_handshake_get_last_in (gnutls_session_t session)

session: is a gnutls_session_t structure.

This function is only useful to check where the last performed handshake failed. If the previous handshake succeed or was not performed at all then no meaningful value will be returned.

Check gnutls_handshake_description_t in gnutls.h for the available handshake descriptions.

Returns: the last handshake message type received, a gnutls_handshake_description_t .

gnutls_handshake_get_last_out

Function: gnutls_handshake_description_t gnutls_handshake_get_last_out (gnutls_session_t session)

session: is a gnutls_session_t structure.

This function is only useful to check where the last performed handshake failed. If the previous handshake succeed or was not performed at all then no meaningful value will be returned.

Check gnutls_handshake_description_t in gnutls.h for the available handshake descriptions.

Returns: the last handshake message type sent, a gnutls_handshake_description_t .

gnutls_handshake_set_max_packet_length

Function: void gnutls_handshake_set_max_packet_length (gnutls_session_t session, size_t max)

session: is a gnutls_session_t structure.

max: is the maximum number.

This function will set the maximum size of all handshake messages. Handshakes over this size are rejected with GNUTLS_E_HANDSHAKE_TOO_LARGE error code. The default value is 48kb which is typically large enough. Set this to 0 if you do not want to set an upper limit.

The reason for restricting the handshake message sizes are to limit Denial of Service attacks.

gnutls_handshake_set_post_client_hello_function

Function: void gnutls_handshake_set_post_client_hello_function (gnutls_session_t session, gnutls_handshake_post_client_hello_func                                                  func)

session: is a gnutls_session_t structure.

func: is the function to be called

This function will set a callback to be called after the client hello has been received (callback valid in server side only). This allows the server to adjust settings based on received extensions.

Those settings could be ciphersuites, requesting certificate, or anything else except for version negotiation (this is done before the hello message is parsed).

This callback must return 0 on success or a gnutls error code to terminate the handshake.

Warning: You should not use this function to terminate the handshake based on client input unless you know what you are doing. Before the handshake is finished there is no way to know if there is a man-in-the-middle attack being performed.

gnutls_handshake_set_private_extensions

Function: void gnutls_handshake_set_private_extensions (gnutls_session_t session, int allow)

session: is a gnutls_session_t structure.

allow: is an integer (0 or 1)

This function will enable or disable the use of private cipher suites (the ones that start with 0xFF). By default or if allow is 0 then these cipher suites will not be advertized nor used.

Currently GnuTLS does not include such cipher-suites or compression algorithms.

Enabling the private ciphersuites when talking to other than gnutls servers and clients may cause interoperability problems.

gnutls_hex2bin

Function: int gnutls_hex2bin (const char * hex_data, size_t hex_size, void * bin_data, size_t * bin_size)

hex_data: string with data in hex format

hex_size: size of hex data

bin_data: output array with binary data

bin_size: when calling should hold maximum size of bin_data , on return will hold actual length of bin_data .

Convert a buffer with hex data to binary data.

Returns: GNUTLS_E_SUCCESS on success, otherwise a negative error code.

Since: 2.4.0

gnutls_hex_decode

Function: int gnutls_hex_decode (const gnutls_datum_t * hex_data, void * result, size_t * result_size)

hex_data: contain the encoded data

result: the place where decoded data will be copied

result_size: holds the size of the result

This function will decode the given encoded data, using the hex encoding used by PSK password files.

Note that hex_data should be null terminated.

Returns: GNUTLS_E_SHORT_MEMORY_BUFFER if the buffer given is not long enough, or 0 on success.

gnutls_hex_encode

Function: int gnutls_hex_encode (const gnutls_datum_t * data, char * result, size_t * result_size)

data: contain the raw data

result: the place where hex data will be copied

result_size: holds the size of the result

This function will convert the given data to printable data, using the hex encoding, as used in the PSK password files.

Returns: GNUTLS_E_SHORT_MEMORY_BUFFER if the buffer given is not long enough, or 0 on success.

gnutls_init

Function: int gnutls_init (gnutls_session_t * session, unsigned int flags)

session: is a pointer to a gnutls_session_t structure.

flags: indicate if this session is to be used for server or client.

This function initializes the current session to null. Every session must be initialized before use, so internal structures can be allocated. This function allocates structures which can only be free’d by calling gnutls_deinit() . Returns GNUTLS_E_SUCCESS (0) on success.

flags can be one of GNUTLS_CLIENT and GNUTLS_SERVER . For a DTLS entity, the flags GNUTLS_DATAGRAM and GNUTLS_NONBLOCK are also available. The latter flag will enable a non-blocking operation of the DTLS timers.

Returns: GNUTLS_E_SUCCESS on success, or an error code.

gnutls_key_generate

Function: int gnutls_key_generate (gnutls_datum_t * key, unsigned int key_size)

key: is a pointer to a gnutls_datum_t which will contain a newly created key.

key_size: The number of bytes of the key.

Generates a random key of key_bytes size.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, or an error code.

Since: 3.0

gnutls_kx_get

Function: gnutls_kx_algorithm_t gnutls_kx_get (gnutls_session_t session)

session: is a gnutls_session_t structure.

Get currently used key exchange algorithm.

Returns: the key exchange algorithm used in the last handshake, a gnutls_kx_algorithm_t value.

gnutls_kx_get_id

Function: gnutls_kx_algorithm_t gnutls_kx_get_id (const char * name)

name: is a KX name

Convert a string to a gnutls_kx_algorithm_t value. The names are compared in a case insensitive way.

Returns: an id of the specified KX algorithm, or GNUTLS_KX_UNKNOWN on error.

gnutls_kx_get_name

Function: const char * gnutls_kx_get_name (gnutls_kx_algorithm_t algorithm)

algorithm: is a key exchange algorithm

Convert a gnutls_kx_algorithm_t value to a string.

Returns: a pointer to a string that contains the name of the specified key exchange algorithm, or NULL .

gnutls_kx_list

Function: const gnutls_kx_algorithm_t * gnutls_kx_list ( void)

Get a list of supported key exchange algorithms.

This function is not thread safe.

Returns: a (0)-terminated list of gnutls_kx_algorithm_t integers indicating the available key exchange algorithms.

gnutls_mac_get

Function: gnutls_mac_algorithm_t gnutls_mac_get (gnutls_session_t session)

session: is a gnutls_session_t structure.

Get currently used MAC algorithm.

Returns: the currently used mac algorithm, a gnutls_mac_algorithm_t value.

gnutls_mac_get_id

Function: gnutls_mac_algorithm_t gnutls_mac_get_id (const char * name)

name: is a MAC algorithm name

Convert a string to a gnutls_mac_algorithm_t value. The names are compared in a case insensitive way.

Returns: a gnutls_mac_algorithm_t id of the specified MAC algorithm string, or GNUTLS_MAC_UNKNOWN on failures.

gnutls_mac_get_key_size

Function: size_t gnutls_mac_get_key_size (gnutls_mac_algorithm_t algorithm)

algorithm: is an encryption algorithm

Get size of MAC key.

Returns: length (in bytes) of the given MAC key size, or 0 if the given MAC algorithm is invalid.

gnutls_mac_get_name

Function: const char * gnutls_mac_get_name (gnutls_mac_algorithm_t algorithm)

algorithm: is a MAC algorithm

Convert a gnutls_mac_algorithm_t value to a string.

Returns: a string that contains the name of the specified MAC algorithm, or NULL .

gnutls_mac_list

Function: const gnutls_mac_algorithm_t * gnutls_mac_list ( void)

Get a list of hash algorithms for use as MACs. Note that not necessarily all MACs are supported in TLS cipher suites. For example, MD2 is not supported as a cipher suite, but is supported for other purposes (e.g., X.509 signature verification or similar).

This function is not thread safe.

Returns: Return a (0)-terminated list of gnutls_mac_algorithm_t integers indicating the available MACs.

gnutls_openpgp_send_cert

Function: void gnutls_openpgp_send_cert (gnutls_session_t session, gnutls_openpgp_crt_status_t status)

session: is a pointer to a gnutls_session_t structure.

status: is one of GNUTLS_OPENPGP_CERT, or GNUTLS_OPENPGP_CERT_FINGERPRINT

This function will order gnutls to send the key fingerprint instead of the key in the initial handshake procedure. This should be used with care and only when there is indication or knowledge that the server can obtain the client’s key.

gnutls_pem_base64_decode

Function: int gnutls_pem_base64_decode (const char * header, const gnutls_datum_t * b64_data, unsigned char * result, size_t * result_size)

header: A null terminated string with the PEM header (eg. CERTIFICATE)

b64_data: contain the encoded data

result: the place where decoded data will be copied

result_size: holds the size of the result

This function will decode the given encoded data. If the header given is non null this function will search for "—–BEGIN header" and decode only this part. Otherwise it will decode the first PEM packet found.

Returns: On success GNUTLS_E_SUCCESS (0) is returned, GNUTLS_E_SHORT_MEMORY_BUFFER is returned if the buffer given is not long enough, or 0 on success.

gnutls_pem_base64_decode_alloc

Function: int gnutls_pem_base64_decode_alloc (const char * header, const gnutls_datum_t * b64_data, gnutls_datum_t * result)

header: The PEM header (eg. CERTIFICATE)

b64_data: contains the encoded data

result: the place where decoded data lie

This function will decode the given encoded data. The decoded data will be allocated, and stored into result. If the header given is non null this function will search for "—–BEGIN header" and decode only this part. Otherwise it will decode the first PEM packet found.

You should use gnutls_free() to free the returned data.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise an error code is returned.

gnutls_pem_base64_encode

Function: int gnutls_pem_base64_encode (const char * msg, const gnutls_datum_t * data, char * result, size_t * result_size)

msg: is a message to be put in the header

data: contain the raw data

result: the place where base64 data will be copied

result_size: holds the size of the result

This function will convert the given data to printable data, using the base64 encoding. This is the encoding used in PEM messages.

The output string will be null terminated, although the size will not include the terminating null.

Returns: On success GNUTLS_E_SUCCESS (0) is returned, GNUTLS_E_SHORT_MEMORY_BUFFER is returned if the buffer given is not long enough, or 0 on success.

gnutls_pem_base64_encode_alloc

Function: int gnutls_pem_base64_encode_alloc (const char * msg, const gnutls_datum_t * data, gnutls_datum_t * result)

msg: is a message to be put in the encoded header

data: contains the raw data

result: will hold the newly allocated encoded data

This function will convert the given data to printable data, using the base64 encoding. This is the encoding used in PEM messages. This function will allocate the required memory to hold the encoded data.

You should use gnutls_free() to free the returned data.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise an error code is returned.

gnutls_perror

Function: void gnutls_perror (int error)

error: is a GnuTLS error code, a negative error code

This function is like perror() . The only difference is that it accepts an error number returned by a gnutls function.

gnutls_pk_algorithm_get_name

Function: const char * gnutls_pk_algorithm_get_name (gnutls_pk_algorithm_t algorithm)

algorithm: is a pk algorithm

Convert a gnutls_pk_algorithm_t value to a string.

Returns: a string that contains the name of the specified public key algorithm, or NULL .

gnutls_pk_bits_to_sec_param

Function: gnutls_sec_param_t gnutls_pk_bits_to_sec_param (gnutls_pk_algorithm_t algo, unsigned int bits)

algo: is a public key algorithm

bits: is the number of bits

This is the inverse of gnutls_sec_param_to_pk_bits() . Given an algorithm and the number of bits, it will return the security parameter. This is a rough indication.

Returns: The security parameter.

Since: 2.12.0

gnutls_pk_get_id

Function: gnutls_pk_algorithm_t gnutls_pk_get_id (const char * name)

name: is a string containing a public key algorithm name.

Convert a string to a gnutls_pk_algorithm_t value. The names are compared in a case insensitive way. For example, gnutls_pk_get_id("RSA") will return GNUTLS_PK_RSA .

Returns: a gnutls_pk_algorithm_t id of the specified public key algorithm string, or GNUTLS_PK_UNKNOWN on failures.

Since: 2.6.0

gnutls_pk_get_name

Function: const char * gnutls_pk_get_name (gnutls_pk_algorithm_t algorithm)

algorithm: is a public key algorithm

Convert a gnutls_pk_algorithm_t value to a string.

Returns: a pointer to a string that contains the name of the specified public key algorithm, or NULL .

Since: 2.6.0

gnutls_pk_list

Function: const gnutls_pk_algorithm_t * gnutls_pk_list ( void)

Get a list of supported public key algorithms.

This function is not thread safe.

Returns: a (0)-terminated list of gnutls_pk_algorithm_t integers indicating the available ciphers.

Since: 2.6.0

gnutls_prf

Function: int gnutls_prf (gnutls_session_t session, size_t label_size, const char * label, int server_random_first, size_t extra_size, const char * extra, size_t outsize, char * out)

session: is a gnutls_session_t structure.

label_size: length of the label variable.

label: label used in PRF computation, typically a short string.

server_random_first: non-0 if server random field should be first in seed

extra_size: length of the extra variable.

extra: optional extra data to seed the PRF with.

outsize: size of pre-allocated output buffer to hold the output.

out: pre-allocate buffer to hold the generated data.

Apply the TLS Pseudo-Random-Function (PRF) on the master secret and the provided data, seeded with the client and server random fields.

The label variable usually contain a string denoting the purpose for the generated data. The server_random_first indicate whether the client random field or the server random field should be first in the seed. Non-0 indicate that the server random field is first, 0 that the client random field is first.

The extra variable can be used to add more data to the seed, after the random variables. It can be used to tie make sure the generated output is strongly connected to some additional data (e.g., a string used in user authentication).

The output is placed in out , which must be pre-allocated.

Returns: GNUTLS_E_SUCCESS on success, or an error code.

gnutls_prf_raw

Function: int gnutls_prf_raw (gnutls_session_t session, size_t label_size, const char * label, size_t seed_size, const char * seed, size_t outsize, char * out)

session: is a gnutls_session_t structure.

label_size: length of the label variable.

label: label used in PRF computation, typically a short string.

seed_size: length of the seed variable.

seed: optional extra data to seed the PRF with.

outsize: size of pre-allocated output buffer to hold the output.

out: pre-allocate buffer to hold the generated data.

Apply the TLS Pseudo-Random-Function (PRF) on the master secret and the provided data.

The label variable usually contain a string denoting the purpose for the generated data. The seed usually contain data such as the client and server random, perhaps together with some additional data that is added to guarantee uniqueness of the output for a particular purpose.

Because the output is not guaranteed to be unique for a particular session unless seed include the client random and server random fields (the PRF would output the same data on another connection resumed from the first one), it is not recommended to use this function directly. The gnutls_prf() function seed the PRF with the client and server random fields directly, and is recommended if you want to generate pseudo random data unique for each session.

Returns: GNUTLS_E_SUCCESS on success, or an error code.

gnutls_priority_certificate_type_list

Function: int gnutls_priority_certificate_type_list (gnutls_priority_t pcache, const unsigned int** list)

pcache: is a gnutls_prioritity_t structure.

list: will point to an integer list

Get a list of available certificate types in the priority structure.

Returns: the number of certificate types, or an error code.

Since: 3.0

gnutls_priority_compression_list

Function: int gnutls_priority_compression_list (gnutls_priority_t pcache, const unsigned int** list)

pcache: is a gnutls_prioritity_t structure.

list: will point to an integer list

Get a list of available compression method in the priority structure.

Returns: the number of methods, or an error code.

Since: 3.0

gnutls_priority_deinit

Function: void gnutls_priority_deinit (gnutls_priority_t priority_cache)

priority_cache: is a gnutls_prioritity_t structure.

Deinitializes the priority cache.

gnutls_priority_ecc_curve_list

Function: int gnutls_priority_ecc_curve_list (gnutls_priority_t pcache, const unsigned int** list)

pcache: is a gnutls_prioritity_t structure.

list: will point to an integer list

Get a list of available elliptic curves in the priority structure.

Returns: the number of curves, or an error code.

Since: 3.0

gnutls_priority_get_cipher_suite_index

Function: int gnutls_priority_get_cipher_suite_index (gnutls_priority_t pcache, unsigned int idx, unsigned int * sidx)

pcache: is a gnutls_prioritity_t structure.

idx: is an index number.

sidx: internal index of cipher suite to get information about.

Provides the internal ciphersuite index to be used with gnutls_cipher_suite_info() . The index idx provided is an index kept at the priorities structure. It might be that a valid priorities index does not correspond to a ciphersuite and in that case GNUTLS_E_UNKNOWN_CIPHER_SUITE will be returned. Once the last available index is crossed then GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.

Returns: On success it returns GNUTLS_E_SUCCESS (0), or a negative error value otherwise.

gnutls_priority_init

Function: int gnutls_priority_init (gnutls_priority_t * priority_cache, const char * priorities, const char ** err_pos)

priority_cache: is a gnutls_prioritity_t structure.

priorities: is a string describing priorities

err_pos: In case of an error this will have the position in the string the error occured

Sets priorities for the ciphers, key exchange methods, macs and compression methods.

The priorities option allows you to specify a colon separated list of the cipher priorities to enable. Some keywords are defined to provide quick access to common preferences.

"PERFORMANCE" means all the "secure" ciphersuites are enabled, limited to 128 bit ciphers and sorted by terms of speed performance.

"NORMAL" means all "secure" ciphersuites. The 256-bit ciphers are included as a fallback only. The ciphers are sorted by security margin.

"SECURE128" means all "secure" ciphersuites of security level 128-bit or more.

"SECURE192" means all "secure" ciphersuites of security level 192-bit or more.

"SUITEB128" means all the NSA SuiteB ciphersuites with security level of 128.

"SUITEB192" means all the NSA SuiteB ciphersuites with security level of 192.

"EXPORT" means all ciphersuites are enabled, including the low-security 40 bit ciphers.

"NONE" means nothing is enabled. This disables even protocols and compression methods.

Special keywords are "!", "-" and "+". "!" or "-" appended with an algorithm will remove this algorithm. "+" appended with an algorithm will add this algorithm.

Check the GnuTLS manual section "Priority strings" for detailed information.

Examples: "NONE:+VERS-TLS-ALL:+MAC-ALL:+RSA:+AES-128-CBC:+SIGN-ALL:+COMP-NULL"

"NORMAL:-ARCFOUR-128" means normal ciphers except for ARCFOUR-128.

"SECURE:-VERS-SSL3.0:+COMP-DEFLATE" means that only secure ciphers are enabled, SSL3.0 is disabled, and libz compression enabled.

"NONE:+VERS-TLS-ALL:+AES-128-CBC:+RSA:+SHA1:+COMP-NULL:+SIGN-RSA-SHA1",

"NONE:+VERS-TLS-ALL:+AES-128-CBC:+ECDHE-RSA:+SHA1:+COMP-NULL:+SIGN-RSA-SHA1:+CURVE-SECP256R1",

"NORMAL:COMPAT " is the most compatible mode.

Returns: On syntax error GNUTLS_E_INVALID_REQUEST is returned, GNUTLS_E_SUCCESS on success, or an error code.

gnutls_priority_protocol_list

Function: int gnutls_priority_protocol_list (gnutls_priority_t pcache, const unsigned int** list)

pcache: is a gnutls_prioritity_t structure.

list: will point to an integer list

Get a list of available TLS version numbers in the priority structure.

Returns: the number of protocols, or an error code.

Since: 3.0

gnutls_priority_set

Function: int gnutls_priority_set (gnutls_session_t session, gnutls_priority_t priority)

session: is a gnutls_session_t structure.

priority: is a gnutls_priority_t structure.

Sets the priorities to use on the ciphers, key exchange methods, macs and compression methods.

Returns: GNUTLS_E_SUCCESS on success, or an error code.

gnutls_priority_set_direct

Function: int gnutls_priority_set_direct (gnutls_session_t session, const char * priorities, const char ** err_pos)

session: is a gnutls_session_t structure.

priorities: is a string describing priorities

err_pos: In case of an error this will have the position in the string the error occured

Sets the priorities to use on the ciphers, key exchange methods, macs and compression methods. This function avoids keeping a priority cache and is used to directly set string priorities to a TLS session. For documentation check the gnutls_priority_init() .

Returns: On syntax error GNUTLS_E_INVALID_REQUEST is returned, GNUTLS_E_SUCCESS on success, or an error code.

gnutls_priority_sign_list

Function: int gnutls_priority_sign_list (gnutls_priority_t pcache, const unsigned int** list)

pcache: is a gnutls_prioritity_t structure.

list: will point to an integer list

Get a list of available signature algorithms in the priority structure.

Returns: the number of algorithms, or an error code.

Since: 3.0

gnutls_protocol_get_id

Function: gnutls_protocol_t gnutls_protocol_get_id (const char * name)

name: is a protocol name

The names are compared in a case insensitive way.

Returns: an id of the specified protocol, or GNUTLS_VERSION_UNKNOWN on error.

gnutls_protocol_get_name

Function: const char * gnutls_protocol_get_name (gnutls_protocol_t version)

version: is a (gnutls) version number

Convert a gnutls_protocol_t value to a string.

Returns: a string that contains the name of the specified TLS version (e.g., "TLS1.0"), or NULL .

gnutls_protocol_get_version

Function: gnutls_protocol_t gnutls_protocol_get_version (gnutls_session_t session)

session: is a gnutls_session_t structure.

Get TLS version, a gnutls_protocol_t value.

Returns: The version of the currently used protocol.

gnutls_protocol_list

Function: const gnutls_protocol_t * gnutls_protocol_list ( void)

Get a list of supported protocols, e.g. SSL 3.0, TLS 1.0 etc.

This function is not thread safe.

Returns: a (0)-terminated list of gnutls_protocol_t integers indicating the available protocols.

gnutls_psk_allocate_client_credentials

Function: int gnutls_psk_allocate_client_credentials (gnutls_psk_client_credentials_t * sc)

sc: is a pointer to a gnutls_psk_server_credentials_t structure.

This structure is complex enough to manipulate directly thus this helper function is provided in order to allocate it.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise an error code is returned.

gnutls_psk_allocate_server_credentials

Function: int gnutls_psk_allocate_server_credentials (gnutls_psk_server_credentials_t * sc)

sc: is a pointer to a gnutls_psk_server_credentials_t structure.

This structure is complex enough to manipulate directly thus this helper function is provided in order to allocate it.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise an error code is returned.

gnutls_psk_client_get_hint

Function: const char * gnutls_psk_client_get_hint (gnutls_session_t session)

session: is a gnutls session

The PSK identity hint may give the client help in deciding which username to use. This should only be called in case of PSK authentication and in case of a client.

Returns: the identity hint of the peer, or NULL in case of an error.

Since: 2.4.0

gnutls_psk_free_client_credentials

Function: void gnutls_psk_free_client_credentials (gnutls_psk_client_credentials_t sc)

sc: is a gnutls_psk_client_credentials_t structure.

This structure is complex enough to manipulate directly thus this helper function is provided in order to free (deallocate) it.

gnutls_psk_free_server_credentials

Function: void gnutls_psk_free_server_credentials (gnutls_psk_server_credentials_t sc)

sc: is a gnutls_psk_server_credentials_t structure.

This structure is complex enough to manipulate directly thus this helper function is provided in order to free (deallocate) it.

gnutls_psk_server_get_username

Function: const char * gnutls_psk_server_get_username (gnutls_session_t session)

session: is a gnutls session

This should only be called in case of PSK authentication and in case of a server.

Returns: the username of the peer, or NULL in case of an error.

gnutls_psk_set_client_credentials

Function: int gnutls_psk_set_client_credentials (gnutls_psk_client_credentials_t res, const char * username, const gnutls_datum_t * key, gnutls_psk_key_flags flags)

res: is a gnutls_psk_client_credentials_t structure.

username: is the user’s zero-terminated userid

key: is the user’s key

flags: indicate the format of the key, either GNUTLS_PSK_KEY_RAW or GNUTLS_PSK_KEY_HEX .

This function sets the username and password, in a gnutls_psk_client_credentials_t structure. Those will be used in PSK authentication. username should be an ASCII string or UTF-8 strings prepared using the "SASLprep" profile of "stringprep". The key can be either in raw byte format or in Hex format (without the 0x prefix).

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise an error code is returned.

gnutls_psk_set_client_credentials_function

Function: void gnutls_psk_set_client_credentials_function (gnutls_psk_client_credentials_t                                             cred, gnutls_psk_client_credentials_function                                             * func)

cred: is a gnutls_psk_server_credentials_t structure.

func: is the callback function

This function can be used to set a callback to retrieve the username and password for client PSK authentication. The callback’s function form is: int (*callback)(gnutls_session_t, char** username, gnutls_datum_t* key);

The username and key ->data must be allocated using gnutls_malloc() . username should be ASCII strings or UTF-8 strings prepared using the "SASLprep" profile of "stringprep".

The callback function will be called once per handshake.

The callback function should return 0 on success. -1 indicates an error.

gnutls_psk_set_params_function

Function: void gnutls_psk_set_params_function (gnutls_psk_server_credentials_t res, gnutls_params_function * func)

res: is a gnutls_psk_server_credentials_t structure

func: is the function to be called

This function will set a callback in order for the server to get the Diffie-Hellman or RSA parameters for PSK authentication. The callback should return GNUTLS_E_SUCCESS (0) on success.

gnutls_psk_set_server_credentials_file

Function: int gnutls_psk_set_server_credentials_file (gnutls_psk_server_credentials_t                                         res, const char * password_file)

res: is a gnutls_psk_server_credentials_t structure.

password_file: is the PSK password file (passwd.psk)

This function sets the password file, in a gnutls_psk_server_credentials_t structure. This password file holds usernames and keys and will be used for PSK authentication.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise an error code is returned.

gnutls_psk_set_server_credentials_function

Function: void gnutls_psk_set_server_credentials_function (gnutls_psk_server_credentials_t                                             cred, gnutls_psk_server_credentials_function                                             * func)

cred: is a gnutls_psk_server_credentials_t structure.

func: is the callback function

This function can be used to set a callback to retrieve the user’s PSK credentials. The callback’s function form is: int (*callback)(gnutls_session_t, const char* username, gnutls_datum_t* key);

username contains the actual username. The key must be filled in using the gnutls_malloc() .

In case the callback returned a negative number then gnutls will assume that the username does not exist.

The callback function will only be called once per handshake. The callback function should return 0 on success, while -1 indicates an error.

gnutls_psk_set_server_credentials_hint

Function: int gnutls_psk_set_server_credentials_hint (gnutls_psk_server_credentials_t res, const char * hint)

res: is a gnutls_psk_server_credentials_t structure.

hint: is the PSK identity hint string

This function sets the identity hint, in a gnutls_psk_server_credentials_t structure. This hint is sent to the client to help it chose a good PSK credential (i.e., username and password).

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise an error code is returned.

Since: 2.4.0

gnutls_psk_set_server_dh_params

Function: void gnutls_psk_set_server_dh_params (gnutls_psk_server_credentials_t res, gnutls_dh_params_t dh_params)

res: is a gnutls_psk_server_credentials_t structure

dh_params: is a structure that holds Diffie-Hellman parameters.

This function will set the Diffie-Hellman parameters for an anonymous server to use. These parameters will be used in Diffie-Hellman exchange with PSK cipher suites.

gnutls_psk_set_server_params_function

Function: void gnutls_psk_set_server_params_function (gnutls_psk_server_credentials_t res, gnutls_params_function * func)

res: is a gnutls_certificate_credentials_t structure

func: is the function to be called

This function will set a callback in order for the server to get the Diffie-Hellman parameters for PSK authentication. The callback should return GNUTLS_E_SUCCESS (0) on success.

gnutls_random_art

Function: int gnutls_random_art (gnutls_random_art_t type, const char* key_type, unsigned int key_size, void * fpr, size_t fpr_size, gnutls_datum_t* art)

type: The type of the random art

key_type: The type of the key (RSA, DSA etc.)

key_size: The size of the key in bits

fpr: The fingerprint of the key

fpr_size: The size of the fingerprint

art: The returned random art

This function will convert a given fingerprint to an "artistic" image. The returned image is allocated using gnutls_malloc()

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise an error code is returned.

gnutls_record_check_pending

Function: size_t gnutls_record_check_pending (gnutls_session_t session)

session: is a gnutls_session_t structure.

This function checks if there are unread data in the gnutls buffers. If the return value is non-zero the next call to gnutls_record_recv() is guarranteed not to block.

Returns: Returns the size of the data or zero.

gnutls_record_disable_padding

Function: void gnutls_record_disable_padding (gnutls_session_t session)

session: is a gnutls_session_t structure.

Used to disabled padding in TLS 1.0 and above. Normally you do not need to use this function, but there are buggy clients that complain if a server pads the encrypted data. This of course will disable protection against statistical attacks on the data.

Normally only servers that require maximum compatibility with everything out there, need to call this function.

gnutls_record_get_direction

Function: int gnutls_record_get_direction (gnutls_session_t session)

session: is a gnutls_session_t structure.

This function provides information about the internals of the record protocol and is only useful if a prior gnutls function call (e.g. gnutls_handshake() ) was interrupted for some reason, that is, if a function returned GNUTLS_E_INTERRUPTED or GNUTLS_E_AGAIN . In such a case, you might want to call select() or poll() before calling the interrupted gnutls function again. To tell you whether a file descriptor should be selected for either reading or writing, gnutls_record_get_direction() returns 0 if the interrupted function was trying to read data, and 1 if it was trying to write data.

Returns: 0 if trying to read data, 1 if trying to write data.

gnutls_record_get_max_size

Function: size_t gnutls_record_get_max_size (gnutls_session_t session)

session: is a gnutls_session_t structure.

Get the record size. The maximum record size is negotiated by the client after the first handshake message.

Returns: The maximum record packet size in this connection.

gnutls_record_recv

Function: ssize_t gnutls_record_recv (gnutls_session_t session, void * data, size_t data_size)

session: is a gnutls_session_t structure.

data: the buffer that the data will be read into

data_size: the number of requested bytes

This function has the similar semantics with recv() . The only difference is that it accepts a GnuTLS session, and uses different error codes. In the special case that a server requests a renegotiation, the client may receive an error code of GNUTLS_E_REHANDSHAKE . This message may be simply ignored, replied with an alert GNUTLS_A_NO_RENEGOTIATION , or replied with a new handshake, depending on the client’s will. If EINTR is returned by the internal push function (the default is recv() ) then GNUTLS_E_INTERRUPTED will be returned. If GNUTLS_E_INTERRUPTED or GNUTLS_E_AGAIN is returned, you must call this function again to get the data. See also gnutls_record_get_direction() . A server may also receive GNUTLS_E_REHANDSHAKE when a client has initiated a handshake. In that case the server can only initiate a handshake or terminate the connection.

Returns: The number of bytes received and zero on EOF (for stream connections). A negative error code is returned in case of an error. The number of bytes received might be less than the requested data_size .

gnutls_record_recv_seq

Function: ssize_t gnutls_record_recv_seq (gnutls_session_t session, void * data, size_t data_size, unsigned char * seq)

session: is a gnutls_session_t structure.

data: the buffer that the data will be read into

data_size: the number of requested bytes

seq: is the packet’s 64-bit sequence number. Should have space for 8 bytes.

This function is the same as gnutls_record_recv() , except that it returns in addition to data, the sequence number of the data. This is useful in DTLS where record packets might be received out-of-order. The returned 8-byte sequence number is an integer in big-endian format and should be treated as a unique message identification.

Returns: The number of bytes received and zero on EOF. A negative error code is returned in case of an error. The number of bytes received might be less than data_size .

Since: 3.0

gnutls_record_send

Function: ssize_t gnutls_record_send (gnutls_session_t session, const void * data, size_t data_size)

session: is a gnutls_session_t structure.

data: contains the data to send

data_size: is the length of the data

This function has the similar semantics with send() . The only difference is that it accepts a GnuTLS session, and uses different error codes. Note that if the send buffer is full, send() will block this function. See the send() documentation for full information. You can replace the default push function by using gnutls_transport_set_ptr2() with a call to send() with a MSG_DONTWAIT flag if blocking is a problem. If the EINTR is returned by the internal push function (the default is send() ) then GNUTLS_E_INTERRUPTED will be returned. If GNUTLS_E_INTERRUPTED or GNUTLS_E_AGAIN is returned, you must call this function again, with the same parameters; alternatively you could provide a NULL pointer for data, and 0 for size. cf. gnutls_record_get_direction() .

Returns: The number of bytes sent, or a negative error code. The number of bytes sent might be less than data_size . The maximum number of bytes this function can send in a single call depends on the negotiated maximum record size.

gnutls_record_set_max_size

Function: ssize_t gnutls_record_set_max_size (gnutls_session_t session, size_t size)

session: is a gnutls_session_t structure.

size: is the new size

This function sets the maximum record packet size in this connection. This property can only be set to clients. The server may choose not to accept the requested size.

Acceptable values are 512(=2^9), 1024(=2^10), 2048(=2^11) and 4096(=2^12). The requested record size does get in effect immediately only while sending data. The receive part will take effect after a successful handshake.

This function uses a TLS extension called ’max record size’. Not all TLS implementations use or even understand this extension.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

gnutls_rehandshake

Function: int gnutls_rehandshake (gnutls_session_t session)

session: is a gnutls_session_t structure.

This function will renegotiate security parameters with the client. This should only be called in case of a server.

This message informs the peer that we want to renegotiate parameters (perform a handshake).

If this function succeeds (returns 0), you must call the gnutls_handshake() function in order to negotiate the new parameters.

Since TLS is full duplex some application data might have been sent during peer’s processing of this message. In that case one should call gnutls_record_recv() until GNUTLS_E_REHANDSHAKE is returned to clear any pending data. Care must be taken if rehandshake is mandatory to terminate if it does not start after some threshold.

If the client does not wish to renegotiate parameters he will should with an alert message, thus the return code will be GNUTLS_E_WARNING_ALERT_RECEIVED and the alert will be GNUTLS_A_NO_RENEGOTIATION . A client may also choose to ignore this message.

Returns: GNUTLS_E_SUCCESS on success, otherwise a negative error code.

gnutls_safe_renegotiation_status

Function: int gnutls_safe_renegotiation_status (gnutls_session_t session)

session: is a gnutls_session_t structure.

Can be used to check whether safe renegotiation is being used in the current session.

Returns: 0 when safe renegotiation is not used and non (0) when safe renegotiation is used.

Since: 2.10.0

gnutls_sec_param_get_name

Function: const char * gnutls_sec_param_get_name (gnutls_sec_param_t param)

param: is a security parameter

Convert a gnutls_sec_param_t value to a string.

Returns: a pointer to a string that contains the name of the specified security level, or NULL .

Since: 2.12.0

gnutls_sec_param_to_pk_bits

Function: unsigned int gnutls_sec_param_to_pk_bits (gnutls_pk_algorithm_t algo, gnutls_sec_param_t param)

algo: is a public key algorithm

param: is a security parameter

When generating private and public key pairs a difficult question is which size of "bits" the modulus will be in RSA and the group size in DSA. The easy answer is 1024, which is also wrong. This function will convert a human understandable security parameter to an appropriate size for the specific algorithm.

Returns: The number of bits, or (0).

Since: 2.12.0

gnutls_server_name_get

Function: int gnutls_server_name_get (gnutls_session_t session, void * data, size_t * data_length, unsigned int * type, unsigned int indx)

session: is a gnutls_session_t structure.

data: will hold the data

data_length: will hold the data length. Must hold the maximum size of data.

type: will hold the server name indicator type

indx: is the index of the server_name

This function will allow you to get the name indication (if any), a client has sent. The name indication may be any of the enumeration gnutls_server_name_type_t.

If type is GNUTLS_NAME_DNS, then this function is to be used by servers that support virtual hosting, and the data will be a null terminated UTF-8 string.

If data has not enough size to hold the server name GNUTLS_E_SHORT_MEMORY_BUFFER is returned, and data_length will hold the required size.

index is used to retrieve more than one server names (if sent by the client). The first server name has an index of 0, the second 1 and so on. If no name with the given index exists GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE is returned.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

gnutls_server_name_set

Function: int gnutls_server_name_set (gnutls_session_t session, gnutls_server_name_type_t type, const void * name, size_t name_length)

session: is a gnutls_session_t structure.

type: specifies the indicator type

name: is a string that contains the server name.

name_length: holds the length of name

This function is to be used by clients that want to inform (via a TLS extension mechanism) the server of the name they connected to. This should be used by clients that connect to servers that do virtual hosting.

The value of name depends on the type type. In case of GNUTLS_NAME_DNS , an ASCII (0)-terminated domain name string, without the trailing dot, is expected. IPv4 or IPv6 addresses are not permitted.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

gnutls_session_channel_binding

Function: int gnutls_session_channel_binding (gnutls_session_t session, gnutls_channel_binding_t cbtype, gnutls_datum_t * cb)

session: is a gnutls_session_t structure.

cbtype: an gnutls_channel_binding_t enumeration type

cb: output buffer array with data

Extract given channel binding data of the cbtype (e.g., GNUTLS_CB_TLS_UNIQUE ) type.

Returns: GNUTLS_E_SUCCESS on success, GNUTLS_E_UNIMPLEMENTED_FEATURE if the cbtype is unsupported, GNUTLS_E_CHANNEL_BINDING_NOT_AVAILABLE if the data is not currently available, or an error code.

Since: 2.12.0

gnutls_session_enable_compatibility_mode

Function: void gnutls_session_enable_compatibility_mode (gnutls_session_t session)

session: is a gnutls_session_t structure.

This function can be used to disable certain (security) features in TLS in order to maintain maximum compatibility with buggy clients. It is equivalent to calling: gnutls_record_disable_padding()

Normally only servers that require maximum compatibility with everything out there, need to call this function.

gnutls_session_get_data

Function: int gnutls_session_get_data (gnutls_session_t session, void * session_data, size_t * session_data_size)

session: is a gnutls_session_t structure.

session_data: is a pointer to space to hold the session.

session_data_size: is the session_data’s size, or it will be set by the function.

Returns all session parameters, in order to support resuming. The client should call this, and keep the returned session, if he wants to resume that current version later by calling gnutls_session_set_data() This function must be called after a successful handshake.

Resuming sessions is really useful and speedups connections after a successful one.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise an error code is returned.

gnutls_session_get_data2

Function: int gnutls_session_get_data2 (gnutls_session_t session, gnutls_datum_t * data)

session: is a gnutls_session_t structure.

data: is a pointer to a datum that will hold the session.

Returns all session parameters, in order to support resuming. The client should call this, and keep the returned session, if he wants to resume that current version later by calling gnutls_session_set_data() . This function must be called after a successful handshake. The returned datum must be freed with gnutls_free() .

Resuming sessions is really useful and speedups connections after a successful one.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise an error code is returned.

gnutls_session_get_id

Function: int gnutls_session_get_id (gnutls_session_t session, void * session_id, size_t * session_id_size)

session: is a gnutls_session_t structure.

session_id: is a pointer to space to hold the session id.

session_id_size: is the session id’s size, or it will be set by the function.

Returns the current session id. This can be used if you want to check if the next session you tried to resume was actually resumed. This is because resumed sessions have the same sessionID with the original session.

Session id is some data set by the server, that identify the current session. In TLS 1.0 and SSL 3.0 session id is always less than 32 bytes.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise an error code is returned.

gnutls_session_get_ptr

Function: void * gnutls_session_get_ptr (gnutls_session_t session)

session: is a gnutls_session_t structure.

Get user pointer for session. Useful in callbacks. This is the pointer set with gnutls_session_set_ptr() .

Returns: the user given pointer from the session structure, or NULL if it was never set.

gnutls_session_get_random

Function: void gnutls_session_get_random (gnutls_session_t session, gnutls_datum_t* client, gnutls_datum_t* server)

session: is a gnutls_session_t structure.

client: the client part of the random

server: the server part of the random

This functions returns pointers to the client and server random fields used in the TLS handshake. The pointers are not to be modified or deallocated.

If a client random value has not yet been established, the output will be garbage.

Since: 3.0

gnutls_session_is_resumed

Function: int gnutls_session_is_resumed (gnutls_session_t session)

session: is a gnutls_session_t structure.

Check whether session is resumed or not.

Returns: non zero if this session is resumed, or a zero if this is a new session.

gnutls_session_resumption_requested

Function: int gnutls_session_resumption_requested (gnutls_session_t session)

session: is a gnutls_session_t structure.

Check whether the client has asked for session resumption. This function is valid only on server side.

Returns: non zero if session resumption was asked, or a zero if not.

gnutls_session_set_data

Function: int gnutls_session_set_data (gnutls_session_t session, const void * session_data, size_t session_data_size)

session: is a gnutls_session_t structure.

session_data: is a pointer to space to hold the session.

session_data_size: is the session’s size

Sets all session parameters, in order to resume a previously established session. The session data given must be the one returned by gnutls_session_get_data() . This function should be called before gnutls_handshake() .

Keep in mind that session resuming is advisory. The server may choose not to resume the session, thus a full handshake will be performed.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise an error code is returned.

gnutls_session_set_ptr

Function: void gnutls_session_set_ptr (gnutls_session_t session, void * ptr)

session: is a gnutls_session_t structure.

ptr: is the user pointer

This function will set (associate) the user given pointer ptr to the session structure. This is pointer can be accessed with gnutls_session_get_ptr() .

gnutls_session_ticket_enable_client

Function: int gnutls_session_ticket_enable_client (gnutls_session_t session)

session: is a gnutls_session_t structure.

Request that the client should attempt session resumption using SessionTicket.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, or an error code.

Since: 2.10.0

gnutls_session_ticket_enable_server

Function: int gnutls_session_ticket_enable_server (gnutls_session_t session, const gnutls_datum_t * key)

session: is a gnutls_session_t structure.

key: key to encrypt session parameters.

Request that the server should attempt session resumption using SessionTicket. key must be initialized with gnutls_session_ticket_key_generate() .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, or an error code.

Since: 2.10.0

gnutls_session_ticket_key_generate

Function: int gnutls_session_ticket_key_generate (gnutls_datum_t * key)

key: is a pointer to a gnutls_datum_t which will contain a newly created key.

Generate a random key to encrypt security parameters within SessionTicket.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, or an error code.

Since: 2.10.0

gnutls_set_default_priority

Function: int gnutls_set_default_priority (gnutls_session_t session)

session: is a gnutls_session_t structure.

Sets some default priority on the ciphers, key exchange methods, macs and compression methods.

This is the same as calling:

gnutls_priority_set_direct (session, "NORMAL", NULL);

This function is kept around for backwards compatibility, but because of its wide use it is still fully supported. If you wish to allow users to provide a string that specify which ciphers to use (which is recommended), you should use gnutls_priority_set_direct() or gnutls_priority_set() instead.

Returns: GNUTLS_E_SUCCESS on success, or an error code.

gnutls_sign_algorithm_get_requested

Function: int gnutls_sign_algorithm_get_requested (gnutls_session_t session, size_t indx, gnutls_sign_algorithm_t * algo)

session: is a gnutls_session_t structure.

indx: is an index of the signature algorithm to return

algo: the returned certificate type will be stored there

Returns the signature algorithm specified by index that was requested by the peer. If the specified index has no data available this function returns GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE . If the negotiated TLS version does not support signature algorithms then GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned even for the first index. The first index is 0.

This function is useful in the certificate callback functions to assist in selecting the correct certificate.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise an error code is returned.

Since: 2.10.0

gnutls_sign_get_id

Function: gnutls_sign_algorithm_t gnutls_sign_get_id (const char * name)

name: is a MAC algorithm name

The names are compared in a case insensitive way.

Returns: return a gnutls_sign_algorithm_t value corresponding to the specified cipher, or GNUTLS_SIGN_UNKNOWN on error.

gnutls_sign_get_name

Function: const char * gnutls_sign_get_name (gnutls_sign_algorithm_t algorithm)

algorithm: is a sign algorithm

Convert a gnutls_sign_algorithm_t value to a string.

Returns: a string that contains the name of the specified sign algorithm, or NULL .

gnutls_sign_list

Function: const gnutls_sign_algorithm_t * gnutls_sign_list ( void)

Get a list of supported public key signature algorithms.

Returns: a (0)-terminated list of gnutls_sign_algorithm_t integers indicating the available ciphers.

gnutls_srp_allocate_client_credentials

Function: int gnutls_srp_allocate_client_credentials (gnutls_srp_client_credentials_t * sc)

sc: is a pointer to a gnutls_srp_server_credentials_t structure.

This structure is complex enough to manipulate directly thus this helper function is provided in order to allocate it.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, or an error code.

gnutls_srp_allocate_server_credentials

Function: int gnutls_srp_allocate_server_credentials (gnutls_srp_server_credentials_t * sc)

sc: is a pointer to a gnutls_srp_server_credentials_t structure.

This structure is complex enough to manipulate directly thus this helper function is provided in order to allocate it.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, or an error code.

gnutls_srp_base64_decode

Function: int gnutls_srp_base64_decode (const gnutls_datum_t * b64_data, char * result, size_t * result_size)

b64_data: contain the encoded data

result: the place where decoded data will be copied

result_size: holds the size of the result

This function will decode the given encoded data, using the base64 encoding found in libsrp.

Note that b64_data should be null terminated.

Warning! This base64 encoding is not the "standard" encoding, so do not use it for non-SRP purposes.

Returns: GNUTLS_E_SHORT_MEMORY_BUFFER if the buffer given is not long enough, or 0 on success.

gnutls_srp_base64_decode_alloc

Function: int gnutls_srp_base64_decode_alloc (const gnutls_datum_t * b64_data, gnutls_datum_t * result)

b64_data: contains the encoded data

result: the place where decoded data lie

This function will decode the given encoded data. The decoded data will be allocated, and stored into result. It will decode using the base64 algorithm as used in libsrp.

You should use gnutls_free() to free the returned data.

Warning! This base64 encoding is not the "standard" encoding, so do not use it for non-SRP purposes.

Returns: 0 on success, or an error code.

gnutls_srp_base64_encode

Function: int gnutls_srp_base64_encode (const gnutls_datum_t * data, char * result, size_t * result_size)

data: contain the raw data

result: the place where base64 data will be copied

result_size: holds the size of the result

This function will convert the given data to printable data, using the base64 encoding, as used in the libsrp. This is the encoding used in SRP password files. If the provided buffer is not long enough GNUTLS_E_SHORT_MEMORY_BUFFER is returned.

Warning! This base64 encoding is not the "standard" encoding, so do not use it for non-SRP purposes.

Returns: GNUTLS_E_SHORT_MEMORY_BUFFER if the buffer given is not long enough, or 0 on success.

gnutls_srp_base64_encode_alloc

Function: int gnutls_srp_base64_encode_alloc (const gnutls_datum_t * data, gnutls_datum_t * result)

data: contains the raw data

result: will hold the newly allocated encoded data

This function will convert the given data to printable data, using the base64 encoding. This is the encoding used in SRP password files. This function will allocate the required memory to hold the encoded data.

You should use gnutls_free() to free the returned data.

Warning! This base64 encoding is not the "standard" encoding, so do not use it for non-SRP purposes.

Returns: 0 on success, or an error code.

gnutls_srp_free_client_credentials

Function: void gnutls_srp_free_client_credentials (gnutls_srp_client_credentials_t sc)

sc: is a gnutls_srp_client_credentials_t structure.

This structure is complex enough to manipulate directly thus this helper function is provided in order to free (deallocate) it.

gnutls_srp_free_server_credentials

Function: void gnutls_srp_free_server_credentials (gnutls_srp_server_credentials_t sc)

sc: is a gnutls_srp_server_credentials_t structure.

This structure is complex enough to manipulate directly thus this helper function is provided in order to free (deallocate) it.

gnutls_srp_server_get_username

Function: const char * gnutls_srp_server_get_username (gnutls_session_t session)

session: is a gnutls session

This function will return the username of the peer. This should only be called in case of SRP authentication and in case of a server. Returns NULL in case of an error.

Returns: SRP username of the peer, or NULL in case of error.

gnutls_srp_set_client_credentials

Function: int gnutls_srp_set_client_credentials (gnutls_srp_client_credentials_t res, const char * username, const char * password)

res: is a gnutls_srp_client_credentials_t structure.

username: is the user’s userid

password: is the user’s password

This function sets the username and password, in a gnutls_srp_client_credentials_t structure. Those will be used in SRP authentication. username and password should be ASCII strings or UTF-8 strings prepared using the "SASLprep" profile of "stringprep".

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, or an error code.

gnutls_srp_set_client_credentials_function

Function: void gnutls_srp_set_client_credentials_function (gnutls_srp_client_credentials_t                                             cred, gnutls_srp_client_credentials_function                                             * func)

cred: is a gnutls_srp_server_credentials_t structure.

func: is the callback function

This function can be used to set a callback to retrieve the username and password for client SRP authentication. The callback’s function form is:

int (*callback)(gnutls_session_t, char** username, char**password);

The username and password must be allocated using gnutls_malloc() . username and password should be ASCII strings or UTF-8 strings prepared using the "SASLprep" profile of "stringprep".

The callback function will be called once per handshake before the initial hello message is sent.

The callback should not return a negative error code the second time called, since the handshake procedure will be aborted.

The callback function should return 0 on success. -1 indicates an error.

gnutls_srp_set_prime_bits

Function: void gnutls_srp_set_prime_bits (gnutls_session_t session, unsigned int bits)

session: is a gnutls_session_t structure.

bits: is the number of bits

This function sets the minimum accepted number of bits, for use in an SRP key exchange. If zero, the default 2048 bits will be used.

In the client side it sets the minimum accepted number of bits. If a server sends a prime with less bits than that GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER will be returned by the handshake.

This function has no effect in server side.

Since: 2.6.0

gnutls_srp_set_server_credentials_file

Function: int gnutls_srp_set_server_credentials_file (gnutls_srp_server_credentials_t res, const char * password_file, const char * password_conf_file)

res: is a gnutls_srp_server_credentials_t structure.

password_file: is the SRP password file (tpasswd)

password_conf_file: is the SRP password conf file (tpasswd.conf)

This function sets the password files, in a gnutls_srp_server_credentials_t structure. Those password files hold usernames and verifiers and will be used for SRP authentication.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, or an error code.

gnutls_srp_set_server_credentials_function

Function: void gnutls_srp_set_server_credentials_function (gnutls_srp_server_credentials_t                                             cred, gnutls_srp_server_credentials_function                                             * func)

cred: is a gnutls_srp_server_credentials_t structure.

func: is the callback function

This function can be used to set a callback to retrieve the user’s SRP credentials. The callback’s function form is:

int (*callback)(gnutls_session_t, const char* username, gnutls_datum_t* salt, gnutls_datum_t *verifier, gnutls_datum_t* g, gnutls_datum_t* n);

username contains the actual username. The salt , verifier , generator and prime must be filled in using the gnutls_malloc() . For convenience prime and generator may also be one of the static parameters defined in gnutls.h.

In case the callback returned a negative number then gnutls will assume that the username does not exist.

In order to prevent attackers from guessing valid usernames, if a user does not exist, g and n values should be filled in using a random user’s parameters. In that case the callback must return the special value (1).

The callback function will only be called once per handshake. The callback function should return 0 on success, while -1 indicates an error.

gnutls_srp_verifier

Function: int gnutls_srp_verifier (const char * username, const char * password, const gnutls_datum_t * salt, const gnutls_datum_t * generator, const gnutls_datum_t * prime, gnutls_datum_t * res)

username: is the user’s name

password: is the user’s password

salt: should be some randomly generated bytes

generator: is the generator of the group

prime: is the group’s prime

res: where the verifier will be stored.

This function will create an SRP verifier, as specified in RFC2945. The prime and generator should be one of the static parameters defined in gnutls/gnutls.h or may be generated.

The verifier will be allocated with gnutls_malloc () and will be stored in res using binary format.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, or an error code.

gnutls_store_commitment

Function: int gnutls_store_commitment (const char* db_name, gnutls_tdb_t tdb, const char* host, const char* service, gnutls_digest_algorithm_t hash_algo, const gnutls_datum_t* hash, time_t expiration, unsigned int flags)

db_name: A file specifying the stored keys (use NULL for the default)

tdb: A storage structure or NULL to use the default

host: The peer’s name

service: non-NULL if this key is specific to a service (e.g. http)

hash_algo: The hash algorithm type

hash: The raw hash

expiration: The expiration time (use 0 to disable expiration)

flags: should be 0.

This function will store the provided hash commitment to the list of stored public keys. The key with the given hash will be considered valid until the provided expiration time.

The store variable if non-null specifies a custom backend for the storage of entries. If it is NULL then the default file backend will be used.

Note that this function is not thread safe with the default backend.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 3.0

gnutls_store_pubkey

Function: int gnutls_store_pubkey (const char* db_name, gnutls_tdb_t tdb, const char* host, const char* service, gnutls_certificate_type_t cert_type, const gnutls_datum_t * cert, time_t expiration, unsigned int flags)

db_name: A file specifying the stored keys (use NULL for the default)

tdb: A storage structure or NULL to use the default

host: The peer’s name

service: non-NULL if this key is specific to a service (e.g. http)

cert_type: The type of the certificate

cert: The data of the certificate

expiration: The expiration time (use 0 to disable expiration)

flags: should be 0.

This function will store the provided certificate to the list of stored public keys. The key will be considered valid until the provided expiration time.

The store variable if non-null specifies a custom backend for the storage of entries. If it is NULL then the default file backend will be used.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 3.0

gnutls_strerror

Function: const char * gnutls_strerror (int error)

error: is a GnuTLS error code, a negative error code

This function is similar to strerror. The difference is that it accepts an error number returned by a gnutls function; In case of an unknown error a descriptive string is sent instead of NULL .

Error codes are always a negative error code.

Returns: A string explaining the GnuTLS error message.

gnutls_strerror_name

Function: const char * gnutls_strerror_name (int error)

error: is an error returned by a gnutls function.

Return the GnuTLS error code define as a string. For example, gnutls_strerror_name (GNUTLS_E_DH_PRIME_UNACCEPTABLE) will return the string "GNUTLS_E_DH_PRIME_UNACCEPTABLE".

Returns: A string corresponding to the symbol name of the error code.

Since: 2.6.0

gnutls_supplemental_get_name

Function: const char * gnutls_supplemental_get_name (gnutls_supplemental_data_format_type_t type)

type: is a supplemental data format type

Convert a gnutls_supplemental_data_format_type_t value to a string.

Returns: a string that contains the name of the specified supplemental data format type, or NULL for unknown types.

gnutls_tdb_deinit

Function: void gnutls_tdb_deinit (gnutls_tdb_t tdb)

tdb: The structure to be deinitialized

This function will deinitialize a public key trust storage structure.

gnutls_tdb_init

Function: int gnutls_tdb_init (gnutls_tdb_t* tdb)

tdb: The structure to be initialized

This function will initialize a public key trust storage structure.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_tdb_set_store_commitment_func

Function: void gnutls_tdb_set_store_commitment_func (gnutls_tdb_t tdb, gnutls_tdb_store_commitment_func cstore)

tdb: The trust storage

cstore: The commitment storage function

This function will associate a commitment (hash) storage function with the trust storage structure. The function is of the following form.

gnutls_tdb_store_commitment_func(const char* db_name, const char* host, const char* service, time_t expiration, gnutls_digest_algorithm_t, const gnutls_datum_t* hash);

gnutls_tdb_set_store_func

Function: void gnutls_tdb_set_store_func (gnutls_tdb_t tdb, gnutls_tdb_store_func store)

tdb: The trust storage

store: The storage function

This function will associate a storage function with the trust storage structure. The function is of the following form.

gnutls_tdb_store_func(const char* db_name, const char* host, const char* service, time_t expiration, const gnutls_datum_t* pubkey);

gnutls_tdb_set_verify_func

Function: void gnutls_tdb_set_verify_func (gnutls_tdb_t tdb, gnutls_tdb_verify_func verify)

tdb: The trust storage

verify: The verification function

This function will associate a retrieval function with the trust storage structure. The function is of the following form.

gnutls_tdb_verify_func(const char* db_name, const char* host, const char* service, const gnutls_datum_t* pubkey);

gnutls_transport_get_ptr

Function: gnutls_transport_ptr_t gnutls_transport_get_ptr (gnutls_session_t session)

session: is a gnutls_session_t structure.

Used to get the first argument of the transport function (like PUSH and PULL). This must have been set using gnutls_transport_set_ptr() .

Returns: The first argument of the transport function.

gnutls_transport_get_ptr2

Function: void gnutls_transport_get_ptr2 (gnutls_session_t session, gnutls_transport_ptr_t * recv_ptr, gnutls_transport_ptr_t * send_ptr)

session: is a gnutls_session_t structure.

recv_ptr: will hold the value for the pull function

send_ptr: will hold the value for the push function

Used to get the arguments of the transport functions (like PUSH and PULL). These should have been set using gnutls_transport_set_ptr2() .

gnutls_transport_set_errno

Function: void gnutls_transport_set_errno (gnutls_session_t session, int err)

session: is a gnutls_session_t structure.

err: error value to store in session-specific errno variable.

Store err in the session-specific errno variable. Useful values for err is EAGAIN and EINTR, other values are treated will be treated as real errors in the push/pull function.

This function is useful in replacement push and pull functions set by gnutls_transport_set_push_function() and gnutls_transport_set_pull_function() under Windows, where the replacements may not have access to the same errno variable that is used by GnuTLS (e.g., the application is linked to msvcr71.dll and gnutls is linked to msvcrt.dll).

gnutls_transport_set_errno_function

Function: void gnutls_transport_set_errno_function (gnutls_session_t session, gnutls_errno_func errno_func)

session: is a gnutls_session_t structure.

errno_func: a callback function similar to write()

This is the function where you set a function to retrieve errno after a failed push or pull operation.

errno_func is of the form, int (*gnutls_errno_func)(gnutls_transport_ptr_t); and should return the errno.

Since: 2.12.0

gnutls_transport_set_ptr

Function: void gnutls_transport_set_ptr (gnutls_session_t session, gnutls_transport_ptr_t ptr)

session: is a gnutls_session_t structure.

ptr: is the value.

Used to set the first argument of the transport function (for push and pull callbacks). In berkeley style sockets this function will set the connection descriptor.

gnutls_transport_set_ptr2

Function: void gnutls_transport_set_ptr2 (gnutls_session_t session, gnutls_transport_ptr_t recv_ptr, gnutls_transport_ptr_t send_ptr)

session: is a gnutls_session_t structure.

recv_ptr: is the value for the pull function

send_ptr: is the value for the push function

Used to set the first argument of the transport function (for push and pull callbacks). In berkeley style sockets this function will set the connection descriptor. With this function you can use two different pointers for receiving and sending.

gnutls_transport_set_pull_function

Function: void gnutls_transport_set_pull_function (gnutls_session_t session, gnutls_pull_func pull_func)

session: is a gnutls_session_t structure.

pull_func: a callback function similar to read()

This is the function where you set a function for gnutls to receive data. Normally, if you use berkeley style sockets, do not need to use this function since the default recv(2) will probably be ok. The callback should return 0 on connection termination, a positive number indicating the number of bytes received, and -1 on error.

gnutls_pull_func is of the form, ssize_t (*gnutls_pull_func)(gnutls_transport_ptr_t, void*, size_t);

gnutls_transport_set_pull_timeout_function

Function: void gnutls_transport_set_pull_timeout_function (gnutls_session_t session, gnutls_pull_timeout_func func)

session: is a gnutls_session_t structure.

func: a callback function

This is the function where you set a function for gnutls to know whether data are ready to be received. It should wait for data a given time frame in milliseconds. The callback should return 0 on timeout, a positive number if data can be received, and -1 on error. You’ll need to override this function if select() is not suitable for the provided transport calls. The callback function is used in DTLS only.

gnutls_pull_timeout_func is of the form, ssize_t (*gnutls_pull_timeout_func)(gnutls_transport_ptr_t, unsigned int ms);

Since: 3.0

gnutls_transport_set_push_function

Function: void gnutls_transport_set_push_function (gnutls_session_t session, gnutls_push_func push_func)

session: is a gnutls_session_t structure.

push_func: a callback function similar to write()

This is the function where you set a push function for gnutls to use in order to send data. If you are going to use berkeley style sockets, you do not need to use this function since the default send(2) will probably be ok. Otherwise you should specify this function for gnutls to be able to send data. The callback should return a positive number indicating the bytes sent, and -1 on error.

push_func is of the form, ssize_t (*gnutls_push_func)(gnutls_transport_ptr_t, const void*, size_t);

gnutls_transport_set_vec_push_function

Function: void gnutls_transport_set_vec_push_function (gnutls_session_t session, gnutls_vec_push_func vec_func)

session: is a gnutls_session_t structure.

vec_func: a callback function similar to writev()

Using this function you can override the default writev(2) function for gnutls to send data. Setting this callback instead of gnutls_transport_set_push_function() is recommended since it introduces less overhead in the TLS handshake process.

vec_func is of the form, ssize_t (*gnutls_vec_push_func) (gnutls_transport_ptr_t, const giovec_t * iov, int iovcnt);

Since: 2.12.0

gnutls_verify_stored_pubkey

Function: int gnutls_verify_stored_pubkey (const char* db_name, gnutls_tdb_t tdb, const char* host, const char* service, gnutls_certificate_type_t cert_type, const gnutls_datum_t * cert, unsigned int flags)

db_name: A file specifying the stored keys (use NULL for the default)

tdb: A storage structure or NULL to use the default

host: The peer’s name

service: non-NULL if this key is specific to a service (e.g. http)

cert_type: The type of the certificate

cert: The raw (der) data of the certificate

flags: should be 0.

This function will try to verify the provided certificate using a list of stored public keys. The service field if non-NULL should be a port number.

The retrieve variable if non-null specifies a custom backend for the retrieval of entries. If it is NULL then the default file backend will be used. In POSIX-like systems the file backend uses the $HOME/.gnutls/known_hosts file.

Note that if the custom storage backend is provided the retrieval function should return GNUTLS_E_CERTIFICATE_KEY_MISMATCH if the host/service pair is found but key doesn’t match, GNUTLS_E_NO_CERTIFICATE_FOUND if no such host/service with the given key is found, and 0 if it was found. The storage function should return 0 on success.

Returns: If no associated public key is found then GNUTLS_E_NO_CERTIFICATE_FOUND will be returned. If a key is found but does not match GNUTLS_E_CERTIFICATE_KEY_MISMATCH is returned. On success, GNUTLS_E_SUCCESS (0) is returned, or a negative error value on other errors.

Since: 3.0

Datagram TLS API

The prototypes for the following functions lie in gnutls/dtls.h.

gnutls_dtls_cookie_send

Function: int gnutls_dtls_cookie_send (gnutls_datum_t* key, void* client_data, size_t client_data_size, gnutls_dtls_prestate_st* prestate, gnutls_transport_ptr_t ptr, gnutls_push_func push_func)

key: is a random key to be used at cookie generation

client_data: contains data identifying the client (i.e. address)

client_data_size: The size of client’s data

prestate: The previous cookie returned by gnutls_dtls_cookie_verify()

ptr: A transport pointer to be used by push_func

push_func: A function that will be used to reply

This function can be used to prevent denial of service attacks to a DTLS server by requiring the client to reply using a cookie sent by this function. That way it can be ensured that a client we allocated resources for (i.e. gnutls_session_t ) is the one that the original incoming packet was originated from.

Returns: the number of bytes sent, or a negative error code.

Since: 3.0

gnutls_dtls_cookie_verify

Function: int gnutls_dtls_cookie_verify (gnutls_datum_t* key, void* client_data, size_t client_data_size, void* _msg, size_t msg_size, gnutls_dtls_prestate_st* prestate)

key: is a random key to be used at cookie generation

client_data: contains data identifying the client (i.e. address)

client_data_size: The size of client’s data

_msg: An incoming message that initiates a connection.

msg_size: The size of the message.

prestate: The cookie of this client.

This function will verify an incoming message for a valid cookie. If a valid cookie is returned then it should be associated with the session using gnutls_dtls_prestate_set() ;

Returns: GNUTLS_E_SUCCESS (0) on success, or a negative error code.

Since: 3.0

gnutls_dtls_get_data_mtu

Function: unsigned int gnutls_dtls_get_data_mtu (gnutls_session_t session)

session: is a gnutls_session_t structure.

This function will return the actual maximum transfer unit for application data. I.e. DTLS headers are subtracted from the actual MTU.

Returns: the maximum allowed transfer unit.

Since: 3.0

gnutls_dtls_get_mtu

Function: unsigned int gnutls_dtls_get_mtu (gnutls_session_t session)

session: is a gnutls_session_t structure.

This function will return the MTU size as set with gnutls_dtls_set_mtu() . This is not the actual MTU of data you can transmit. Use gnutls_dtls_get_data_mtu() for that reason.

Returns: the set maximum transfer unit.

Since: 3.0

gnutls_dtls_get_timeout

Function: unsigned int gnutls_dtls_get_timeout (gnutls_session_t session)

session: is a gnutls_session_t structure.

This function will return the milliseconds remaining for a retransmission of the previously sent handshake message. This function is useful when DTLS is used in non-blocking mode, to estimate when to call gnutls_handshake() if no packets have been received.

Returns: the remaining time in milliseconds.

Since: 3.0

gnutls_dtls_prestate_set

Function: void gnutls_dtls_prestate_set (gnutls_session_t session, gnutls_dtls_prestate_st* prestate)

session: a new session

prestate: contains the client’s prestate

This function will associate the prestate acquired by the cookie authentication with the client, with the newly established session.

Since: 3.0

gnutls_dtls_set_mtu

Function: void gnutls_dtls_set_mtu (gnutls_session_t session, unsigned int mtu)

session: is a gnutls_session_t structure.

mtu: The maximum transfer unit of the interface

This function will set the maximum transfer unit of the interface that DTLS packets are expected to leave from.

Since: 3.0

gnutls_dtls_set_timeouts

Function: void gnutls_dtls_set_timeouts (gnutls_session_t session, unsigned int retrans_timeout, unsigned int total_timeout)

session: is a gnutls_session_t structure.

retrans_timeout: The time at which a retransmission will occur in milliseconds

total_timeout: The time at which the connection will be aborted, in milliseconds.

This function will set the timeouts required for the DTLS handshake protocol. The retransmission timeout is the time after which a message from the peer is not received, the previous messages will be retransmitted. The total timeout is the time after which the handshake will be aborted with GNUTLS_E_TIMEDOUT .

The DTLS protocol recommends the values of 1 sec and 60 seconds respectively.

If the retransmission timeout is zero then the handshake will operate in a non-blocking way, i.e., return GNUTLS_E_AGAIN .

Since: 3.0

gnutls_record_get_discarded

Function: unsigned int gnutls_record_get_discarded (gnutls_session_t session)

session: is a gnutls_session_t structure.

Returns the number of discarded packets in a DTLS connection.

Returns: The number of discarded packets.

Since: 3.0

X.509 certificate API

The following functions are to be used for X.509 certificate handling. Their prototypes lie in gnutls/x509.h.

gnutls_pkcs7_deinit

Function: void gnutls_pkcs7_deinit (gnutls_pkcs7_t pkcs7)

pkcs7: The structure to be initialized

This function will deinitialize a PKCS7 structure.

gnutls_pkcs7_delete_crl

Function: int gnutls_pkcs7_delete_crl (gnutls_pkcs7_t pkcs7, int indx)

pkcs7: should contain a gnutls_pkcs7_t structure

indx: the index of the crl to delete

This function will delete a crl from a PKCS7 or RFC2630 crl set. Index starts from 0. Returns 0 on success.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_pkcs7_delete_crt

Function: int gnutls_pkcs7_delete_crt (gnutls_pkcs7_t pkcs7, int indx)

pkcs7: should contain a gnutls_pkcs7_t structure

indx: the index of the certificate to delete

This function will delete a certificate from a PKCS7 or RFC2630 certificate set. Index starts from 0. Returns 0 on success.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_pkcs7_export

Function: int gnutls_pkcs7_export (gnutls_pkcs7_t pkcs7, gnutls_x509_crt_fmt_t format, void * output_data, size_t * output_data_size)

pkcs7: Holds the pkcs7 structure

format: the format of output params. One of PEM or DER.

output_data: will contain a structure PEM or DER encoded

output_data_size: holds the size of output_data (and will be replaced by the actual size of parameters)

This function will export the pkcs7 structure to DER or PEM format.

If the buffer provided is not long enough to hold the output, then * output_data_size is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will be returned.

If the structure is PEM encoded, it will have a header of "BEGIN PKCS7".

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_pkcs7_get_crl_count

Function: int gnutls_pkcs7_get_crl_count (gnutls_pkcs7_t pkcs7)

pkcs7: should contain a gnutls_pkcs7_t structure

This function will return the number of certifcates in the PKCS7 or RFC2630 crl set.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_pkcs7_get_crl_raw

Function: int gnutls_pkcs7_get_crl_raw (gnutls_pkcs7_t pkcs7, int indx, void * crl, size_t * crl_size)

pkcs7: should contain a gnutls_pkcs7_t structure

indx: contains the index of the crl to extract

crl: the contents of the crl will be copied there (may be null)

crl_size: should hold the size of the crl

This function will return a crl of the PKCS7 or RFC2630 crl set.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value. If the provided buffer is not long enough, then crl_size is updated and GNUTLS_E_SHORT_MEMORY_BUFFER is returned. After the last crl has been read GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.

gnutls_pkcs7_get_crt_count

Function: int gnutls_pkcs7_get_crt_count (gnutls_pkcs7_t pkcs7)

pkcs7: should contain a gnutls_pkcs7_t structure

This function will return the number of certifcates in the PKCS7 or RFC2630 certificate set.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_pkcs7_get_crt_raw

Function: int gnutls_pkcs7_get_crt_raw (gnutls_pkcs7_t pkcs7, int indx, void * certificate, size_t * certificate_size)

pkcs7: should contain a gnutls_pkcs7_t structure

indx: contains the index of the certificate to extract

certificate: the contents of the certificate will be copied there (may be null)

certificate_size: should hold the size of the certificate

This function will return a certificate of the PKCS7 or RFC2630 certificate set.

After the last certificate has been read GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value. If the provided buffer is not long enough, then certificate_size is updated and GNUTLS_E_SHORT_MEMORY_BUFFER is returned.

gnutls_pkcs7_import

Function: int gnutls_pkcs7_import (gnutls_pkcs7_t pkcs7, const gnutls_datum_t * data, gnutls_x509_crt_fmt_t format)

pkcs7: The structure to store the parsed PKCS7.

data: The DER or PEM encoded PKCS7.

format: One of DER or PEM

This function will convert the given DER or PEM encoded PKCS7 to the native gnutls_pkcs7_t format. The output will be stored in pkcs7 .

If the PKCS7 is PEM encoded it should have a header of "PKCS7".

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_pkcs7_init

Function: int gnutls_pkcs7_init (gnutls_pkcs7_t * pkcs7)

pkcs7: The structure to be initialized

This function will initialize a PKCS7 structure. PKCS7 structures usually contain lists of X.509 Certificates and X.509 Certificate revocation lists.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_pkcs7_set_crl

Function: int gnutls_pkcs7_set_crl (gnutls_pkcs7_t pkcs7, gnutls_x509_crl_t crl)

pkcs7: should contain a gnutls_pkcs7_t structure

crl: the DER encoded crl to be added

This function will add a parsed CRL to the PKCS7 or RFC2630 crl set.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_pkcs7_set_crl_raw

Function: int gnutls_pkcs7_set_crl_raw (gnutls_pkcs7_t pkcs7, const gnutls_datum_t * crl)

pkcs7: should contain a gnutls_pkcs7_t structure

crl: the DER encoded crl to be added

This function will add a crl to the PKCS7 or RFC2630 crl set.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_pkcs7_set_crt

Function: int gnutls_pkcs7_set_crt (gnutls_pkcs7_t pkcs7, gnutls_x509_crt_t crt)

pkcs7: should contain a gnutls_pkcs7_t structure

crt: the certificate to be copied.

This function will add a parsed certificate to the PKCS7 or RFC2630 certificate set. This is a wrapper function over gnutls_pkcs7_set_crt_raw() .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_pkcs7_set_crt_raw

Function: int gnutls_pkcs7_set_crt_raw (gnutls_pkcs7_t pkcs7, const gnutls_datum_t * crt)

pkcs7: should contain a gnutls_pkcs7_t structure

crt: the DER encoded certificate to be added

This function will add a certificate to the PKCS7 or RFC2630 certificate set.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crl_check_issuer

Function: int gnutls_x509_crl_check_issuer (gnutls_x509_crl_t crl, gnutls_x509_crt_t issuer)

crl: is the CRL to be checked

issuer: is the certificate of a possible issuer

This function will check if the given CRL was issued by the given issuer certificate. It will return true (1) if the given CRL was issued by the given issuer, and false (0) if not.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crl_deinit

Function: void gnutls_x509_crl_deinit (gnutls_x509_crl_t crl)

crl: The structure to be initialized

This function will deinitialize a CRL structure.

gnutls_x509_crl_export

Function: int gnutls_x509_crl_export (gnutls_x509_crl_t crl, gnutls_x509_crt_fmt_t format, void * output_data, size_t * output_data_size)

crl: Holds the revocation list

format: the format of output params. One of PEM or DER.

output_data: will contain a private key PEM or DER encoded

output_data_size: holds the size of output_data (and will be replaced by the actual size of parameters)

This function will export the revocation list to DER or PEM format.

If the buffer provided is not long enough to hold the output, then GNUTLS_E_SHORT_MEMORY_BUFFER will be returned.

If the structure is PEM encoded, it will have a header of "BEGIN X509 CRL".

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value. and a negative error code on failure.

gnutls_x509_crl_get_authority_key_gn_serial

Function: int gnutls_x509_crl_get_authority_key_gn_serial (gnutls_x509_crl_t crl, unsigned int seq, void * alt, size_t * alt_size, unsigned int * alt_type, void* serial, size_t * serial_size, unsigned int * critical)

crl: should contain a gnutls_x509_crl_t structure

seq: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)

alt: is the place where the alternative name will be copied to

alt_size: holds the size of alt.

alt_type: holds the type of the alternative name (one of gnutls_x509_subject_alt_name_t).

serial: buffer to store the serial number (may be null)

serial_size: Holds the size of the serial field (may be null)

critical: will be non (0) if the extension is marked as critical (may be null)

This function will return the X.509 authority key identifier when stored as a general name (authorityCertIssuer) and serial number.

Because more than one general names might be stored seq can be used as a counter to request them all until GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE is returned.

Returns: Returns 0 on success, or an error code.

Since: 3.0

gnutls_x509_crl_get_authority_key_id

Function: int gnutls_x509_crl_get_authority_key_id (gnutls_x509_crl_t crl, void * id, size_t * id_size, unsigned int * critical)

crl: should contain a gnutls_x509_crl_t structure

id: The place where the identifier will be copied

id_size: Holds the size of the result field.

critical: will be non (0) if the extension is marked as critical (may be null)

This function will return the CRL authority’s key identifier. This is obtained by the X.509 Authority Key identifier extension field (2.5.29.35). Note that this function only returns the keyIdentifier field of the extension and GNUTLS_E_X509_UNSUPPORTED_EXTENSION , if the extension contains the name and serial number of the certificate. In that case gnutls_x509_crl_get_authority_key_gn_serial() may be used.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code in case of an error.

Since: 2.8.0

gnutls_x509_crl_get_crt_count

Function: int gnutls_x509_crl_get_crt_count (gnutls_x509_crl_t crl)

crl: should contain a gnutls_x509_crl_t structure

This function will return the number of revoked certificates in the given CRL.

Returns: number of certificates, a negative error code on failure.

gnutls_x509_crl_get_crt_serial

Function: int gnutls_x509_crl_get_crt_serial (gnutls_x509_crl_t crl, int indx, unsigned char * serial, size_t * serial_size, time_t * t)

crl: should contain a gnutls_x509_crl_t structure

indx: the index of the certificate to extract (starting from 0)

serial: where the serial number will be copied

serial_size: initially holds the size of serial

t: if non null, will hold the time this certificate was revoked

This function will retrieve the serial number of the specified, by the index, revoked certificate.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value. and a negative error code on error.

gnutls_x509_crl_get_dn_oid

Function: int gnutls_x509_crl_get_dn_oid (gnutls_x509_crl_t crl, int indx, void * oid, size_t * sizeof_oid)

crl: should contain a gnutls_x509_crl_t structure

indx: Specifies which DN OID to send. Use (0) to get the first one.

oid: a pointer to a structure to hold the name (may be null)

sizeof_oid: initially holds the size of ’oid’

This function will extract the requested OID of the name of the CRL issuer, specified by the given index.

If oid is null then only the size will be filled.

Returns: GNUTLS_E_SHORT_MEMORY_BUFFER if the provided buffer is not long enough, and in that case the sizeof_oid will be updated with the required size. On success 0 is returned.

gnutls_x509_crl_get_extension_data

Function: int gnutls_x509_crl_get_extension_data (gnutls_x509_crl_t crl, int indx, void * data, size_t * sizeof_data)

crl: should contain a gnutls_x509_crl_t structure

indx: Specifies which extension OID to send. Use (0) to get the first one.

data: a pointer to a structure to hold the data (may be null)

sizeof_data: initially holds the size of oid

This function will return the requested extension data in the CRL. The extension data will be stored as a string in the provided buffer.

Use gnutls_x509_crl_get_extension_info() to extract the OID and critical flag. Use gnutls_x509_crl_get_extension_info() instead, if you want to get data indexed by the extension OID rather than sequence.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code in case of an error. If your have reached the last extension available GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.

Since: 2.8.0

gnutls_x509_crl_get_extension_info

Function: int gnutls_x509_crl_get_extension_info (gnutls_x509_crl_t crl, int indx, void * oid, size_t * sizeof_oid, unsigned int * critical)

crl: should contain a gnutls_x509_crl_t structure

indx: Specifies which extension OID to send, use (0) to get the first one.

oid: a pointer to a structure to hold the OID

sizeof_oid: initially holds the maximum size of oid , on return holds actual size of oid .

critical: output variable with critical flag, may be NULL.

This function will return the requested extension OID in the CRL, and the critical flag for it. The extension OID will be stored as a string in the provided buffer. Use gnutls_x509_crl_get_extension_data() to extract the data.

If the buffer provided is not long enough to hold the output, then * sizeof_oid is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will be returned.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code in case of an error. If your have reached the last extension available GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.

Since: 2.8.0

gnutls_x509_crl_get_extension_oid

Function: int gnutls_x509_crl_get_extension_oid (gnutls_x509_crl_t crl, int indx, void * oid, size_t * sizeof_oid)

crl: should contain a gnutls_x509_crl_t structure

indx: Specifies which extension OID to send, use (0) to get the first one.

oid: a pointer to a structure to hold the OID (may be null)

sizeof_oid: initially holds the size of oid

This function will return the requested extension OID in the CRL. The extension OID will be stored as a string in the provided buffer.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code in case of an error. If your have reached the last extension available GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.

Since: 2.8.0

gnutls_x509_crl_get_issuer_dn

Function: int gnutls_x509_crl_get_issuer_dn (const gnutls_x509_crl_t crl, char * buf, size_t * sizeof_buf)

crl: should contain a gnutls_x509_crl_t structure

buf: a pointer to a structure to hold the peer’s name (may be null)

sizeof_buf: initially holds the size of buf

This function will copy the name of the CRL issuer in the provided buffer. The name will be in the form "C=xxxx,O=yyyy,CN=zzzz" as described in RFC4514. The output string will be ASCII or UTF-8 encoded, depending on the certificate data.

If buf is NULL then only the size will be filled.

Returns: GNUTLS_E_SHORT_MEMORY_BUFFER if the provided buffer is not long enough, and in that case the sizeof_buf will be updated with the required size, and 0 on success.

gnutls_x509_crl_get_issuer_dn_by_oid

Function: int gnutls_x509_crl_get_issuer_dn_by_oid (gnutls_x509_crl_t crl, const char * oid, int indx, unsigned int raw_flag, void * buf, size_t * sizeof_buf)

crl: should contain a gnutls_x509_crl_t structure

oid: holds an Object Identified in null terminated string

indx: In case multiple same OIDs exist in the RDN, this specifies which to send. Use (0) to get the first one.

raw_flag: If non (0) returns the raw DER data of the DN part.

buf: a pointer to a structure to hold the peer’s name (may be null)

sizeof_buf: initially holds the size of buf

This function will extract the part of the name of the CRL issuer specified by the given OID. The output will be encoded as described in RFC4514. The output string will be ASCII or UTF-8 encoded, depending on the certificate data.

Some helper macros with popular OIDs can be found in gnutls/x509.h If raw flag is (0), this function will only return known OIDs as text. Other OIDs will be DER encoded, as described in RFC4514 – in hex format with a ’#’ prefix. You can check about known OIDs using gnutls_x509_dn_oid_known() .

If buf is null then only the size will be filled.

Returns: GNUTLS_E_SHORT_MEMORY_BUFFER if the provided buffer is not long enough, and in that case the sizeof_buf will be updated with the required size, and 0 on success.

gnutls_x509_crl_get_next_update

Function: time_t gnutls_x509_crl_get_next_update (gnutls_x509_crl_t crl)

crl: should contain a gnutls_x509_crl_t structure

This function will return the time the next CRL will be issued. This field is optional in a CRL so it might be normal to get an error instead.

Returns: when the next CRL will be issued, or (time_t)-1 on error.

gnutls_x509_crl_get_number

Function: int gnutls_x509_crl_get_number (gnutls_x509_crl_t crl, void * ret, size_t * ret_size, unsigned int * critical)

crl: should contain a gnutls_x509_crl_t structure

ret: The place where the number will be copied

ret_size: Holds the size of the result field.

critical: will be non (0) if the extension is marked as critical (may be null)

This function will return the CRL number extension. This is obtained by the CRL Number extension field (2.5.29.20).

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code in case of an error.

Since: 2.8.0

gnutls_x509_crl_get_raw_issuer_dn

Function: int gnutls_x509_crl_get_raw_issuer_dn (gnutls_x509_crl_t crl, gnutls_datum_t * dn)

crl: should contain a gnutls_x509_crl_t structure

dn: will hold the starting point of the DN

This function will return a pointer to the DER encoded DN structure and the length.

Returns: a negative error code on error, and (0) on success.

Since: 2.12.0

gnutls_x509_crl_get_signature

Function: int gnutls_x509_crl_get_signature (gnutls_x509_crl_t crl, char * sig, size_t * sizeof_sig)

crl: should contain a gnutls_x509_crl_t structure

sig: a pointer where the signature part will be copied (may be null).

sizeof_sig: initially holds the size of sig

This function will extract the signature field of a CRL.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value. and a negative error code on error.

gnutls_x509_crl_get_signature_algorithm

Function: int gnutls_x509_crl_get_signature_algorithm (gnutls_x509_crl_t crl)

crl: should contain a gnutls_x509_crl_t structure

This function will return a value of the gnutls_sign_algorithm_t enumeration that is the signature algorithm.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crl_get_this_update

Function: time_t gnutls_x509_crl_get_this_update (gnutls_x509_crl_t crl)

crl: should contain a gnutls_x509_crl_t structure

This function will return the time this CRL was issued.

Returns: when the CRL was issued, or (time_t)-1 on error.

gnutls_x509_crl_get_version

Function: int gnutls_x509_crl_get_version (gnutls_x509_crl_t crl)

crl: should contain a gnutls_x509_crl_t structure

This function will return the version of the specified CRL.

Returns: The version number, or a negative error code on error.

gnutls_x509_crl_import

Function: int gnutls_x509_crl_import (gnutls_x509_crl_t crl, const gnutls_datum_t * data, gnutls_x509_crt_fmt_t format)

crl: The structure to store the parsed CRL.

data: The DER or PEM encoded CRL.

format: One of DER or PEM

This function will convert the given DER or PEM encoded CRL to the native gnutls_x509_crl_t format. The output will be stored in ’crl’.

If the CRL is PEM encoded it should have a header of "X509 CRL".

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crl_init

Function: int gnutls_x509_crl_init (gnutls_x509_crl_t * crl)

crl: The structure to be initialized

This function will initialize a CRL structure. CRL stands for Certificate Revocation List. A revocation list usually contains lists of certificate serial numbers that have been revoked by an Authority. The revocation lists are always signed with the authority’s private key.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crl_list_import

Function: int gnutls_x509_crl_list_import (gnutls_x509_crl_t * crls, unsigned int * crl_max, const gnutls_datum_t * data, gnutls_x509_crt_fmt_t format, unsigned int flags)

crls: The structures to store the parsed CRLs. Must not be initialized.

crl_max: Initially must hold the maximum number of crls. It will be updated with the number of crls available.

data: The PEM encoded CRLs

format: One of DER or PEM.

flags: must be (0) or an OR’d sequence of gnutls_certificate_import_flags.

This function will convert the given PEM encoded CRL list to the native gnutls_x509_crl_t format. The output will be stored in crls . They will be automatically initialized.

If the Certificate is PEM encoded it should have a header of "X509 CRL".

Returns: the number of certificates read or a negative error value.

Since: 3.0

gnutls_x509_crl_list_import2

Function: int gnutls_x509_crl_list_import2 (gnutls_x509_crl_t ** crls, unsigned int * size, const gnutls_datum_t * data, gnutls_x509_crt_fmt_t format, unsigned int flags)

crls: The structures to store the parsed crl list. Must not be initialized.

size: It will contain the size of the list.

data: The PEM encoded CRL.

format: One of DER or PEM.

flags: must be (0) or an OR’d sequence of gnutls_certificate_import_flags.

This function will convert the given PEM encoded CRL list to the native gnutls_x509_crl_t format. The output will be stored in crls . They will be automatically initialized.

If the Certificate is PEM encoded it should have a header of "X509 CRL".

Returns: the number of certificates read or a negative error value.

Since: 3.0

gnutls_x509_crl_print

Function: int gnutls_x509_crl_print (gnutls_x509_crl_t crl, gnutls_certificate_print_formats_t format, gnutls_datum_t * out)

crl: The structure to be printed

format: Indicate the format to use

out: Newly allocated datum with (0) terminated string.

This function will pretty print a X.509 certificate revocation list, suitable for display to a human.

The output out needs to be deallocate using gnutls_free() .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crl_set_authority_key_id

Function: int gnutls_x509_crl_set_authority_key_id (gnutls_x509_crl_t crl, const void * id, size_t id_size)

crl: a CRL of type gnutls_x509_crl_t

id: The key ID

id_size: Holds the size of the serial field.

This function will set the CRL’s authority key ID extension. Only the keyIdentifier field can be set with this function. This may be used by an authority that holds multiple private keys, to distinguish the used key.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.8.0

gnutls_x509_crl_set_crt

Function: int gnutls_x509_crl_set_crt (gnutls_x509_crl_t crl, gnutls_x509_crt_t crt, time_t revocation_time)

crl: should contain a gnutls_x509_crl_t structure

crt: a certificate of type gnutls_x509_crt_t with the revoked certificate

revocation_time: The time this certificate was revoked

This function will set a revoked certificate’s serial number to the CRL.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crl_set_crt_serial

Function: int gnutls_x509_crl_set_crt_serial (gnutls_x509_crl_t crl, const void * serial, size_t serial_size, time_t revocation_time)

crl: should contain a gnutls_x509_crl_t structure

serial: The revoked certificate’s serial number

serial_size: Holds the size of the serial field.

revocation_time: The time this certificate was revoked

This function will set a revoked certificate’s serial number to the CRL.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crl_set_next_update

Function: int gnutls_x509_crl_set_next_update (gnutls_x509_crl_t crl, time_t exp_time)

crl: should contain a gnutls_x509_crl_t structure

exp_time: The actual time

This function will set the time this CRL will be updated.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crl_set_number

Function: int gnutls_x509_crl_set_number (gnutls_x509_crl_t crl, const void * nr, size_t nr_size)

crl: a CRL of type gnutls_x509_crl_t

nr: The CRL number

nr_size: Holds the size of the nr field.

This function will set the CRL’s number extension. This is to be used as a unique and monotonic number assigned to the CRL by the authority.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.8.0

gnutls_x509_crl_set_this_update

Function: int gnutls_x509_crl_set_this_update (gnutls_x509_crl_t crl, time_t act_time)

crl: should contain a gnutls_x509_crl_t structure

act_time: The actual time

This function will set the time this CRL was issued.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crl_set_version

Function: int gnutls_x509_crl_set_version (gnutls_x509_crl_t crl, unsigned int version)

crl: should contain a gnutls_x509_crl_t structure

version: holds the version number. For CRLv1 crls must be 1.

This function will set the version of the CRL. This must be one for CRL version 1, and so on. The CRLs generated by gnutls should have a version number of 2.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crl_sign2

Function: int gnutls_x509_crl_sign2 (gnutls_x509_crl_t crl, gnutls_x509_crt_t issuer, gnutls_x509_privkey_t issuer_key, gnutls_digest_algorithm_t dig, unsigned int flags)

crl: should contain a gnutls_x509_crl_t structure

issuer: is the certificate of the certificate issuer

issuer_key: holds the issuer’s private key

dig: The message digest to use. GNUTLS_DIG_SHA1 is the safe choice unless you know what you’re doing.

flags: must be 0

This function will sign the CRL with the issuer’s private key, and will copy the issuer’s information into the CRL.

This must be the last step in a certificate CRL since all the previously set parameters are now signed.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crl_verify

Function: int gnutls_x509_crl_verify (gnutls_x509_crl_t crl, const gnutls_x509_crt_t * CA_list, int CA_list_length, unsigned int flags, unsigned int * verify)

crl: is the crl to be verified

CA_list: is a certificate list that is considered to be trusted one

CA_list_length: holds the number of CA certificates in CA_list

flags: Flags that may be used to change the verification algorithm. Use OR of the gnutls_certificate_verify_flags enumerations.

verify: will hold the crl verification output.

This function will try to verify the given crl and return its status. See gnutls_x509_crt_list_verify() for a detailed description of return values.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crq_deinit

Function: void gnutls_x509_crq_deinit (gnutls_x509_crq_t crq)

crq: The structure to be initialized

This function will deinitialize a PKCS10 certificate request structure.

gnutls_x509_crq_export

Function: int gnutls_x509_crq_export (gnutls_x509_crq_t crq, gnutls_x509_crt_fmt_t format, void * output_data, size_t * output_data_size)

crq: should contain a gnutls_x509_crq_t structure

format: the format of output params. One of PEM or DER.

output_data: will contain a certificate request PEM or DER encoded

output_data_size: holds the size of output_data (and will be replaced by the actual size of parameters)

This function will export the certificate request to a PEM or DER encoded PKCS10 structure.

If the buffer provided is not long enough to hold the output, then GNUTLS_E_SHORT_MEMORY_BUFFER will be returned and * output_data_size will be updated.

If the structure is PEM encoded, it will have a header of "BEGIN NEW CERTIFICATE REQUEST".

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crq_get_attribute_by_oid

Function: int gnutls_x509_crq_get_attribute_by_oid (gnutls_x509_crq_t crq, const char * oid, int indx, void * buf, size_t * sizeof_buf)

crq: should contain a gnutls_x509_crq_t structure

oid: holds an Object Identified in (0)-terminated string

indx: In case multiple same OIDs exist in the attribute list, this specifies which to send, use (0) to get the first one

buf: a pointer to a structure to hold the attribute data (may be NULL )

sizeof_buf: initially holds the size of buf

This function will return the attribute in the certificate request specified by the given Object ID. The attribute will be DER encoded.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crq_get_attribute_data

Function: int gnutls_x509_crq_get_attribute_data (gnutls_x509_crq_t crq, int indx, void * data, size_t * sizeof_data)

crq: should contain a gnutls_x509_crq_t structure

indx: Specifies which attribute OID to send. Use (0) to get the first one.

data: a pointer to a structure to hold the data (may be null)

sizeof_data: initially holds the size of oid

This function will return the requested attribute data in the certificate request. The attribute data will be stored as a string in the provided buffer.

Use gnutls_x509_crq_get_attribute_info() to extract the OID. Use gnutls_x509_crq_get_attribute_by_oid() instead, if you want to get data indexed by the attribute OID rather than sequence.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code in case of an error. If your have reached the last extension available GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.

Since: 2.8.0

gnutls_x509_crq_get_attribute_info

Function: int gnutls_x509_crq_get_attribute_info (gnutls_x509_crq_t crq, int indx, void * oid, size_t * sizeof_oid)

crq: should contain a gnutls_x509_crq_t structure

indx: Specifies which attribute OID to send. Use (0) to get the first one.

oid: a pointer to a structure to hold the OID

sizeof_oid: initially holds the maximum size of oid , on return holds actual size of oid .

This function will return the requested attribute OID in the certificate, and the critical flag for it. The attribute OID will be stored as a string in the provided buffer. Use gnutls_x509_crq_get_attribute_data() to extract the data.

If the buffer provided is not long enough to hold the output, then * sizeof_oid is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will be returned.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code in case of an error. If your have reached the last extension available GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.

Since: 2.8.0

gnutls_x509_crq_get_basic_constraints

Function: int gnutls_x509_crq_get_basic_constraints (gnutls_x509_crq_t crq, unsigned int * critical, unsigned int * ca, int * pathlen)

crq: should contain a gnutls_x509_crq_t structure

critical: will be non (0) if the extension is marked as critical

ca: pointer to output integer indicating CA status, may be NULL, value is 1 if the certificate CA flag is set, 0 otherwise.

pathlen: pointer to output integer indicating path length (may be NULL), non-negative error codes indicate a present pathLenConstraint field and the actual value, -1 indicate that the field is absent.

This function will read the certificate’s basic constraints, and return the certificates CA status. It reads the basicConstraints X.509 extension (2.5.29.19).

Returns: If the certificate is a CA a positive value will be returned, or (0) if the certificate does not have CA flag set. A negative error code may be returned in case of errors. If the certificate does not contain the basicConstraints extension GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.

Since: 2.8.0

gnutls_x509_crq_get_challenge_password

Function: int gnutls_x509_crq_get_challenge_password (gnutls_x509_crq_t crq, char * pass, size_t * sizeof_pass)

crq: should contain a gnutls_x509_crq_t structure

pass: will hold a (0)-terminated password string

sizeof_pass: Initially holds the size of pass .

This function will return the challenge password in the request. The challenge password is intended to be used for requesting a revocation of the certificate.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crq_get_dn

Function: int gnutls_x509_crq_get_dn (gnutls_x509_crq_t crq, char * buf, size_t * sizeof_buf)

crq: should contain a gnutls_x509_crq_t structure

buf: a pointer to a structure to hold the name (may be NULL )

sizeof_buf: initially holds the size of buf

This function will copy the name of the Certificate request subject to the provided buffer. The name will be in the form "C=xxxx,O=yyyy,CN=zzzz" as described in RFC 2253. The output string buf will be ASCII or UTF-8 encoded, depending on the certificate data.

Returns: GNUTLS_E_SHORT_MEMORY_BUFFER if the provided buffer is not long enough, and in that case the * sizeof_buf will be updated with the required size. On success 0 is returned.

gnutls_x509_crq_get_dn_by_oid

Function: int gnutls_x509_crq_get_dn_by_oid (gnutls_x509_crq_t crq, const char * oid, int indx, unsigned int raw_flag, void * buf, size_t * sizeof_buf)

crq: should contain a gnutls_x509_crq_t structure

oid: holds an Object Identified in null terminated string

indx: In case multiple same OIDs exist in the RDN, this specifies which to send. Use (0) to get the first one.

raw_flag: If non (0) returns the raw DER data of the DN part.

buf: a pointer to a structure to hold the name (may be NULL )

sizeof_buf: initially holds the size of buf

This function will extract the part of the name of the Certificate request subject, specified by the given OID. The output will be encoded as described in RFC2253. The output string will be ASCII or UTF-8 encoded, depending on the certificate data.

Some helper macros with popular OIDs can be found in gnutls/x509.h If raw flag is (0), this function will only return known OIDs as text. Other OIDs will be DER encoded, as described in RFC2253 – in hex format with a ’\#’ prefix. You can check about known OIDs using gnutls_x509_dn_oid_known() .

Returns: GNUTLS_E_SHORT_MEMORY_BUFFER if the provided buffer is not long enough, and in that case the * sizeof_buf will be updated with the required size. On success 0 is returned.

gnutls_x509_crq_get_dn_oid

Function: int gnutls_x509_crq_get_dn_oid (gnutls_x509_crq_t crq, int indx, void * oid, size_t * sizeof_oid)

crq: should contain a gnutls_x509_crq_t structure

indx: Specifies which DN OID to send. Use (0) to get the first one.

oid: a pointer to a structure to hold the name (may be NULL )

sizeof_oid: initially holds the size of oid

This function will extract the requested OID of the name of the certificate request subject, specified by the given index.

Returns: GNUTLS_E_SHORT_MEMORY_BUFFER if the provided buffer is not long enough, and in that case the * sizeof_oid will be updated with the required size. On success 0 is returned.

gnutls_x509_crq_get_extension_by_oid

Function: int gnutls_x509_crq_get_extension_by_oid (gnutls_x509_crq_t crq, const char * oid, int indx, void * buf, size_t * sizeof_buf, unsigned int * critical)

crq: should contain a gnutls_x509_crq_t structure

oid: holds an Object Identified in null terminated string

indx: In case multiple same OIDs exist in the extensions, this specifies which to send. Use (0) to get the first one.

buf: a pointer to a structure to hold the name (may be null)

sizeof_buf: initially holds the size of buf

critical: will be non (0) if the extension is marked as critical

This function will return the extension specified by the OID in the certificate. The extensions will be returned as binary data DER encoded, in the provided buffer.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code in case of an error. If the certificate does not contain the specified extension GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.

Since: 2.8.0

gnutls_x509_crq_get_extension_data

Function: int gnutls_x509_crq_get_extension_data (gnutls_x509_crq_t crq, int indx, void * data, size_t * sizeof_data)

crq: should contain a gnutls_x509_crq_t structure

indx: Specifies which extension OID to send. Use (0) to get the first one.

data: a pointer to a structure to hold the data (may be null)

sizeof_data: initially holds the size of oid

This function will return the requested extension data in the certificate. The extension data will be stored as a string in the provided buffer.

Use gnutls_x509_crq_get_extension_info() to extract the OID and critical flag. Use gnutls_x509_crq_get_extension_by_oid() instead, if you want to get data indexed by the extension OID rather than sequence.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code in case of an error. If your have reached the last extension available GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.

Since: 2.8.0

gnutls_x509_crq_get_extension_info

Function: int gnutls_x509_crq_get_extension_info (gnutls_x509_crq_t crq, int indx, void * oid, size_t * sizeof_oid, unsigned int * critical)

crq: should contain a gnutls_x509_crq_t structure

indx: Specifies which extension OID to send. Use (0) to get the first one.

oid: a pointer to a structure to hold the OID

sizeof_oid: initially holds the maximum size of oid , on return holds actual size of oid .

critical: output variable with critical flag, may be NULL.

This function will return the requested extension OID in the certificate, and the critical flag for it. The extension OID will be stored as a string in the provided buffer. Use gnutls_x509_crq_get_extension_data() to extract the data.

If the buffer provided is not long enough to hold the output, then * sizeof_oid is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will be returned.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code in case of an error. If your have reached the last extension available GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.

Since: 2.8.0

gnutls_x509_crq_get_key_id

Function: int gnutls_x509_crq_get_key_id (gnutls_x509_crq_t crq, unsigned int flags, unsigned char * output_data, size_t * output_data_size)

crq: a certificate of type gnutls_x509_crq_t

flags: should be 0 for now

output_data: will contain the key ID

output_data_size: holds the size of output_data (and will be replaced by the actual size of parameters)

This function will return a unique ID the depends on the public key parameters. This ID can be used in checking whether a certificate corresponds to the given private key.

If the buffer provided is not long enough to hold the output, then * output_data_size is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will be returned. The output will normally be a SHA-1 hash output, which is 20 bytes.

Returns: In case of failure a negative error code will be returned, and 0 on success.

Since: 2.8.0

gnutls_x509_crq_get_key_purpose_oid

Function: int gnutls_x509_crq_get_key_purpose_oid (gnutls_x509_crq_t crq, int indx, void * oid, size_t * sizeof_oid, unsigned int * critical)

crq: should contain a gnutls_x509_crq_t structure

indx: This specifies which OID to return, use (0) to get the first one

oid: a pointer to a buffer to hold the OID (may be NULL )

sizeof_oid: initially holds the size of oid

critical: output variable with critical flag, may be NULL .

This function will extract the key purpose OIDs of the Certificate specified by the given index. These are stored in the Extended Key Usage extension (2.5.29.37). See the GNUTLS_KP_* definitions for human readable names.

Returns: GNUTLS_E_SHORT_MEMORY_BUFFER if the provided buffer is not long enough, and in that case the * sizeof_oid will be updated with the required size. On success 0 is returned.

Since: 2.8.0

gnutls_x509_crq_get_key_rsa_raw

Function: int gnutls_x509_crq_get_key_rsa_raw (gnutls_x509_crq_t crq, gnutls_datum_t * m, gnutls_datum_t * e)

crq: Holds the certificate

m: will hold the modulus

e: will hold the public exponent

This function will export the RSA public key’s parameters found in the given structure. The new parameters will be allocated using gnutls_malloc() and will be stored in the appropriate datum.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.8.0

gnutls_x509_crq_get_key_usage

Function: int gnutls_x509_crq_get_key_usage (gnutls_x509_crq_t crq, unsigned int * key_usage, unsigned int * critical)

crq: should contain a gnutls_x509_crq_t structure

key_usage: where the key usage bits will be stored

critical: will be non (0) if the extension is marked as critical

This function will return certificate’s key usage, by reading the keyUsage X.509 extension (2.5.29.15). The key usage value will ORed values of the: GNUTLS_KEY_DIGITAL_SIGNATURE , GNUTLS_KEY_NON_REPUDIATION , GNUTLS_KEY_KEY_ENCIPHERMENT , GNUTLS_KEY_DATA_ENCIPHERMENT , GNUTLS_KEY_KEY_AGREEMENT , GNUTLS_KEY_KEY_CERT_SIGN , GNUTLS_KEY_CRL_SIGN , GNUTLS_KEY_ENCIPHER_ONLY , GNUTLS_KEY_DECIPHER_ONLY .

Returns: the certificate key usage, or a negative error code in case of parsing error. If the certificate does not contain the keyUsage extension GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.

Since: 2.8.0

gnutls_x509_crq_get_pk_algorithm

Function: int gnutls_x509_crq_get_pk_algorithm (gnutls_x509_crq_t crq, unsigned int * bits)

crq: should contain a gnutls_x509_crq_t structure

bits: if bits is non-NULL it will hold the size of the parameters’ in bits

This function will return the public key algorithm of a PKCS10 certificate request.

If bits is non-NULL , it should have enough size to hold the parameters size in bits. For RSA the bits returned is the modulus. For DSA the bits returned are of the public exponent.

Returns: a member of the gnutls_pk_algorithm_t enumeration on success, or a negative error code on error.

gnutls_x509_crq_get_private_key_usage_period

Function: int gnutls_x509_crq_get_private_key_usage_period (gnutls_x509_crq_t crq, time_t* activation, time_t* expiration, unsigned int * critical)

crq: – undescribed –

activation: The activation time

expiration: The expiration time

critical: the extension status

This function will return the expiration and activation times of the private key of the certificate.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE if the extension is not present, otherwise a negative error value.

gnutls_x509_crq_get_subject_alt_name

Function: int gnutls_x509_crq_get_subject_alt_name (gnutls_x509_crq_t crq, unsigned int seq, void * ret, size_t * ret_size, unsigned int * ret_type, unsigned int * critical)

crq: should contain a gnutls_x509_crq_t structure

seq: specifies the sequence number of the alt name, 0 for the first one, 1 for the second etc.

ret: is the place where the alternative name will be copied to

ret_size: holds the size of ret.

ret_type: holds the gnutls_x509_subject_alt_name_t name type

critical: will be non (0) if the extension is marked as critical (may be null)

This function will return the alternative names, contained in the given certificate. It is the same as gnutls_x509_crq_get_subject_alt_name() except for the fact that it will return the type of the alternative name in ret_type even if the function fails for some reason (i.e. the buffer provided is not enough).

Returns: the alternative subject name type on success, one of the enumerated gnutls_x509_subject_alt_name_t . It will return GNUTLS_E_SHORT_MEMORY_BUFFER if ret_size is not large enough to hold the value. In that case ret_size will be updated with the required size. If the certificate request does not have an Alternative name with the specified sequence number then GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE is returned.

Since: 2.8.0

gnutls_x509_crq_get_subject_alt_othername_oid

Function: int gnutls_x509_crq_get_subject_alt_othername_oid (gnutls_x509_crq_t crq, unsigned int seq, void * ret, size_t * ret_size)

crq: should contain a gnutls_x509_crq_t structure

seq: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)

ret: is the place where the otherName OID will be copied to

ret_size: holds the size of ret.

This function will extract the type OID of an otherName Subject Alternative Name, contained in the given certificate, and return the type as an enumerated element.

This function is only useful if gnutls_x509_crq_get_subject_alt_name() returned GNUTLS_SAN_OTHERNAME .

Returns: the alternative subject name type on success, one of the enumerated gnutls_x509_subject_alt_name_t. For supported OIDs, it will return one of the virtual (GNUTLS_SAN_OTHERNAME_*) types, e.g. GNUTLS_SAN_OTHERNAME_XMPP , and GNUTLS_SAN_OTHERNAME for unknown OIDs. It will return GNUTLS_E_SHORT_MEMORY_BUFFER if ret_size is not large enough to hold the value. In that case ret_size will be updated with the required size. If the certificate does not have an Alternative name with the specified sequence number and with the otherName type then GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE is returned.

Since: 2.8.0

gnutls_x509_crq_get_version

Function: int gnutls_x509_crq_get_version (gnutls_x509_crq_t crq)

crq: should contain a gnutls_x509_crq_t structure

This function will return the version of the specified Certificate request.

Returns: version of certificate request, or a negative error code on error.

gnutls_x509_crq_import

Function: int gnutls_x509_crq_import (gnutls_x509_crq_t crq, const gnutls_datum_t * data, gnutls_x509_crt_fmt_t format)

crq: The structure to store the parsed certificate request.

data: The DER or PEM encoded certificate.

format: One of DER or PEM

This function will convert the given DER or PEM encoded certificate request to a gnutls_x509_crq_t structure. The output will be stored in crq .

If the Certificate is PEM encoded it should have a header of "NEW CERTIFICATE REQUEST".

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crq_init

Function: int gnutls_x509_crq_init (gnutls_x509_crq_t * crq)

crq: The structure to be initialized

This function will initialize a PKCS10 certificate request structure.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crq_print

Function: int gnutls_x509_crq_print (gnutls_x509_crq_t crq, gnutls_certificate_print_formats_t format, gnutls_datum_t * out)

crq: The structure to be printed

format: Indicate the format to use

out: Newly allocated datum with (0) terminated string.

This function will pretty print a certificate request, suitable for display to a human.

The output out needs to be deallocate using gnutls_free() .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.8.0

gnutls_x509_crq_set_attribute_by_oid

Function: int gnutls_x509_crq_set_attribute_by_oid (gnutls_x509_crq_t crq, const char * oid, void * buf, size_t sizeof_buf)

crq: should contain a gnutls_x509_crq_t structure

oid: holds an Object Identified in (0)-terminated string

buf: a pointer to a structure that holds the attribute data

sizeof_buf: holds the size of buf

This function will set the attribute in the certificate request specified by the given Object ID. The attribute must be be DER encoded.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crq_set_basic_constraints

Function: int gnutls_x509_crq_set_basic_constraints (gnutls_x509_crq_t crq, unsigned int ca, int pathLenConstraint)

crq: a certificate request of type gnutls_x509_crq_t

ca: true(1) or false(0) depending on the Certificate authority status.

pathLenConstraint: non-negative error codes indicate maximum length of path, and negative error codes indicate that the pathLenConstraints field should not be present.

This function will set the basicConstraints certificate extension.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.8.0

gnutls_x509_crq_set_challenge_password

Function: int gnutls_x509_crq_set_challenge_password (gnutls_x509_crq_t crq, const char * pass)

crq: should contain a gnutls_x509_crq_t structure

pass: holds a (0)-terminated password

This function will set a challenge password to be used when revoking the request.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crq_set_dn_by_oid

Function: int gnutls_x509_crq_set_dn_by_oid (gnutls_x509_crq_t crq, const char * oid, unsigned int raw_flag, const void * data, unsigned int sizeof_data)

crq: should contain a gnutls_x509_crq_t structure

oid: holds an Object Identifier in a (0)-terminated string

raw_flag: must be 0, or 1 if the data are DER encoded

data: a pointer to the input data

sizeof_data: holds the size of data

This function will set the part of the name of the Certificate request subject, specified by the given OID. The input string should be ASCII or UTF-8 encoded.

Some helper macros with popular OIDs can be found in gnutls/x509.h With this function you can only set the known OIDs. You can test for known OIDs using gnutls_x509_dn_oid_known() . For OIDs that are not known (by gnutls) you should properly DER encode your data, and call this function with raw_flag set.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crq_set_key

Function: int gnutls_x509_crq_set_key (gnutls_x509_crq_t crq, gnutls_x509_privkey_t key)

crq: should contain a gnutls_x509_crq_t structure

key: holds a private key

This function will set the public parameters from the given private key to the request.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crq_set_key_purpose_oid

Function: int gnutls_x509_crq_set_key_purpose_oid (gnutls_x509_crq_t crq, const void * oid, unsigned int critical)

crq: a certificate of type gnutls_x509_crq_t

oid: a pointer to a (0)-terminated string that holds the OID

critical: Whether this extension will be critical or not

This function will set the key purpose OIDs of the Certificate. These are stored in the Extended Key Usage extension (2.5.29.37) See the GNUTLS_KP_* definitions for human readable names.

Subsequent calls to this function will append OIDs to the OID list.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.8.0

gnutls_x509_crq_set_key_rsa_raw

Function: int gnutls_x509_crq_set_key_rsa_raw (gnutls_x509_crq_t crq, const gnutls_datum_t * m, const gnutls_datum_t * e)

crq: should contain a gnutls_x509_crq_t structure

m: holds the modulus

e: holds the public exponent

This function will set the public parameters from the given private key to the request. Only RSA keys are currently supported.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.6.0

gnutls_x509_crq_set_key_usage

Function: int gnutls_x509_crq_set_key_usage (gnutls_x509_crq_t crq, unsigned int usage)

crq: a certificate request of type gnutls_x509_crq_t

usage: an ORed sequence of the GNUTLS_KEY_* elements.

This function will set the keyUsage certificate extension.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.8.0

gnutls_x509_crq_set_private_key_usage_period

Function: int gnutls_x509_crq_set_private_key_usage_period (gnutls_x509_crq_t crq, time_t activation, time_t expiration)

crq: a certificate of type gnutls_x509_crq_t

activation: The activation time

expiration: The expiration time

This function will set the private key usage period extension (2.5.29.16).

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crq_set_subject_alt_name

Function: int gnutls_x509_crq_set_subject_alt_name (gnutls_x509_crq_t crq, gnutls_x509_subject_alt_name_t nt, const void * data, unsigned int data_size, unsigned int flags)

crq: a certificate request of type gnutls_x509_crq_t

nt: is one of the gnutls_x509_subject_alt_name_t enumerations

data: The data to be set

data_size: The size of data to be set

flags: GNUTLS_FSAN_SET to clear previous data or GNUTLS_FSAN_APPEND to append.

This function will set the subject alternative name certificate extension. It can set the following types:

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.8.0

gnutls_x509_crq_set_version

Function: int gnutls_x509_crq_set_version (gnutls_x509_crq_t crq, unsigned int version)

crq: should contain a gnutls_x509_crq_t structure

version: holds the version number, for v1 Requests must be 1

This function will set the version of the certificate request. For version 1 requests this must be one.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crq_sign2

Function: int gnutls_x509_crq_sign2 (gnutls_x509_crq_t crq, gnutls_x509_privkey_t key, gnutls_digest_algorithm_t dig, unsigned int flags)

crq: should contain a gnutls_x509_crq_t structure

key: holds a private key

dig: The message digest to use, i.e., GNUTLS_DIG_SHA1

flags: must be 0

This function will sign the certificate request with a private key. This must be the same key as the one used in gnutls_x509_crt_set_key() since a certificate request is self signed.

This must be the last step in a certificate request generation since all the previously set parameters are now signed.

Returns: GNUTLS_E_SUCCESS on success, otherwise a negative error code. GNUTLS_E_ASN1_VALUE_NOT_FOUND is returned if you didn’t set all information in the certificate request (e.g., the version using gnutls_x509_crq_set_version() ).

gnutls_x509_crq_verify

Function: int gnutls_x509_crq_verify (gnutls_x509_crq_t crq, unsigned int flags)

crq: is the crq to be verified

flags: Flags that may be used to change the verification algorithm. Use OR of the gnutls_certificate_verify_flags enumerations.

This function will verify self signature in the certificate request and return its status.

Returns: In case of a verification failure GNUTLS_E_PK_SIG_VERIFY_FAILED is returned, and zero or positive code on success.

Since 2.12.0

gnutls_x509_crt_check_hostname

Function: int gnutls_x509_crt_check_hostname (gnutls_x509_crt_t cert, const char * hostname)

cert: should contain an gnutls_x509_crt_t structure

hostname: A null terminated string that contains a DNS name

This function will check if the given certificate’s subject matches the given hostname. This is a basic implementation of the matching described in RFC2818 (HTTPS), which takes into account wildcards, and the DNSName/IPAddress subject alternative name PKIX extension.

Returns: non (0) for a successful match, and (0) on failure.

gnutls_x509_crt_check_issuer

Function: int gnutls_x509_crt_check_issuer (gnutls_x509_crt_t cert, gnutls_x509_crt_t issuer)

cert: is the certificate to be checked

issuer: is the certificate of a possible issuer

This function will check if the given certificate was issued by the given issuer.

Returns: It will return true (1) if the given certificate is issued by the given issuer, and false (0) if not. A negative error code is returned in case of an error.

gnutls_x509_crt_check_revocation

Function: int gnutls_x509_crt_check_revocation (gnutls_x509_crt_t cert, const gnutls_x509_crl_t * crl_list, int crl_list_length)

cert: should contain a gnutls_x509_crt_t structure

crl_list: should contain a list of gnutls_x509_crl_t structures

crl_list_length: the length of the crl_list

This function will return check if the given certificate is revoked. It is assumed that the CRLs have been verified before.

Returns: 0 if the certificate is NOT revoked, and 1 if it is. A negative error code is returned on error.

gnutls_x509_crt_cpy_crl_dist_points

Function: int gnutls_x509_crt_cpy_crl_dist_points (gnutls_x509_crt_t dst, gnutls_x509_crt_t src)

dst: a certificate of type gnutls_x509_crt_t

src: the certificate where the dist points will be copied from

This function will copy the CRL distribution points certificate extension, from the source to the destination certificate. This may be useful to copy from a CA certificate to issued ones.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crt_deinit

Function: void gnutls_x509_crt_deinit (gnutls_x509_crt_t cert)

cert: The structure to be deinitialized

This function will deinitialize a certificate structure.

gnutls_x509_crt_export

Function: int gnutls_x509_crt_export (gnutls_x509_crt_t cert, gnutls_x509_crt_fmt_t format, void * output_data, size_t * output_data_size)

cert: Holds the certificate

format: the format of output params. One of PEM or DER.

output_data: will contain a certificate PEM or DER encoded

output_data_size: holds the size of output_data (and will be replaced by the actual size of parameters)

This function will export the certificate to DER or PEM format.

If the buffer provided is not long enough to hold the output, then *output_data_size is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will be returned.

If the structure is PEM encoded, it will have a header of "BEGIN CERTIFICATE".

Returns: In case of failure a negative error code will be returned, and 0 on success.

gnutls_x509_crt_get_activation_time

Function: time_t gnutls_x509_crt_get_activation_time (gnutls_x509_crt_t cert)

cert: should contain a gnutls_x509_crt_t structure

This function will return the time this Certificate was or will be activated.

Returns: activation time, or (time_t)-1 on error.

gnutls_x509_crt_get_authority_info_access

Function: int gnutls_x509_crt_get_authority_info_access (gnutls_x509_crt_t crt, unsigned int seq, int what, gnutls_datum_t * data, unsigned int * critical)

crt: Holds the certificate

seq: specifies the sequence number of the access descriptor (0 for the first one, 1 for the second etc.)

what: what data to get, a gnutls_info_access_what_t type.

data: output data to be freed with gnutls_free() .

critical: pointer to output integer that is set to non-0 if the extension is marked as critical (may be NULL )

This function extracts the Authority Information Access (AIA) extension, see RFC 5280 section 4.2.2.1 for more information. The AIA extension holds a sequence of AccessDescription (AD) data:

<informalexample><programlisting> AuthorityInfoAccessSyntax ::= SEQUENCE SIZE (1..MAX) OF AccessDescription

AccessDescription ::= SEQUENCE { accessMethod OBJECT IDENTIFIER, accessLocation GeneralName } </programlisting></informalexample>

The seq input parameter is used to indicate which member of the sequence the caller is interested in. The first member is 0, the second member 1 and so on. When the seq value is out of bounds, GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE is returned.

The type of data returned in data is specified via what which should be gnutls_info_access_what_t values.

If what is GNUTLS_IA_ACCESSMETHOD_OID then data will hold the accessMethod OID (e.g., "1.3.6.1.5.5.7.48.1").

If what is GNUTLS_IA_ACCESSLOCATION_GENERALNAME_TYPE , data will hold the accessLocation GeneralName type (e.g., "uniformResourceIdentifier").

If what is GNUTLS_IA_URI , data will hold the accessLocation URI data. Requesting this what value leads to an error if the accessLocation is not of the "uniformResourceIdentifier" type.

If what is GNUTLS_IA_OCSP_URI , data will hold the OCSP URI. Requesting this what value leads to an error if the accessMethod is not 1.3.6.1.5.5.7.48.1 aka OSCP, or if accessLocation is not of the "uniformResourceIdentifier" type.

If what is GNUTLS_IA_CAISSUERS_URI , data will hold the caIssuers URI. Requesting this what value leads to an error if the accessMethod is not 1.3.6.1.5.5.7.48.2 aka caIssuers, or if accessLocation is not of the "uniformResourceIdentifier" type.

More what values may be allocated in the future as needed.

If data is NULL, the function does the same without storing the output data, that is, it will set critical and do error checking as usual.

The value of the critical flag is returned in * critical . Supply a NULL critical if you want the function to make sure the extension is non-critical, as required by RFC 5280.

Returns: GNUTLS_E_SUCCESS on success, GNUTLS_E_INVALID_REQUEST on invalid crt , GNUTLS_E_CONSTRAINT_ERROR if the extension is incorrectly marked as critical (use a non-NULL critical to override), GNUTLS_E_UNKNOWN_ALGORITHM if the requested OID does not match (e.g., when using GNUTLS_IA_OCSP_URI ), otherwise a negative error code.

Since: 3.0

gnutls_x509_crt_get_authority_key_gn_serial

Function: int gnutls_x509_crt_get_authority_key_gn_serial (gnutls_x509_crt_t cert, unsigned int seq, void * alt, size_t * alt_size, unsigned int * alt_type, void* serial, size_t * serial_size, unsigned int * critical)

cert: should contain a gnutls_x509_crt_t structure

seq: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)

alt: is the place where the alternative name will be copied to

alt_size: holds the size of alt.

alt_type: holds the type of the alternative name (one of gnutls_x509_subject_alt_name_t).

serial: buffer to store the serial number (may be null)

serial_size: Holds the size of the serial field (may be null)

critical: will be non (0) if the extension is marked as critical (may be null)

This function will return the X.509 authority key identifier when stored as a general name (authorityCertIssuer) and serial number.

Because more than one general names might be stored seq can be used as a counter to request them all until GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE is returned.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE if the extension is not present, otherwise a negative error value.

Since: 3.0

gnutls_x509_crt_get_authority_key_id

Function: int gnutls_x509_crt_get_authority_key_id (gnutls_x509_crt_t cert, void * id, size_t * id_size, unsigned int * critical)

cert: should contain a gnutls_x509_crt_t structure

id: The place where the identifier will be copied

id_size: Holds the size of the id field.

critical: will be non (0) if the extension is marked as critical (may be null)

This function will return the X.509v3 certificate authority’s key identifier. This is obtained by the X.509 Authority Key identifier extension field (2.5.29.35). Note that this function only returns the keyIdentifier field of the extension and GNUTLS_E_X509_UNSUPPORTED_EXTENSION , if the extension contains the name and serial number of the certificate. In that case gnutls_x509_crt_get_authority_key_gn_serial() may be used.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE if the extension is not present, otherwise a negative error value.

gnutls_x509_crt_get_basic_constraints

Function: int gnutls_x509_crt_get_basic_constraints (gnutls_x509_crt_t cert, unsigned int * critical, unsigned int * ca, int * pathlen)

cert: should contain a gnutls_x509_crt_t structure

critical: will be non (0) if the extension is marked as critical

ca: pointer to output integer indicating CA status, may be NULL, value is 1 if the certificate CA flag is set, 0 otherwise.

pathlen: pointer to output integer indicating path length (may be NULL), non-negative error codes indicate a present pathLenConstraint field and the actual value, -1 indicate that the field is absent.

This function will read the certificate’s basic constraints, and return the certificates CA status. It reads the basicConstraints X.509 extension (2.5.29.19).

Returns: If the certificate is a CA a positive value will be returned, or (0) if the certificate does not have CA flag set. A negative error code may be returned in case of errors. If the certificate does not contain the basicConstraints extension GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.

gnutls_x509_crt_get_ca_status

Function: int gnutls_x509_crt_get_ca_status (gnutls_x509_crt_t cert, unsigned int * critical)

cert: should contain a gnutls_x509_crt_t structure

critical: will be non (0) if the extension is marked as critical

This function will return certificates CA status, by reading the basicConstraints X.509 extension (2.5.29.19). If the certificate is a CA a positive value will be returned, or (0) if the certificate does not have CA flag set.

Use gnutls_x509_crt_get_basic_constraints() if you want to read the pathLenConstraint field too.

Returns: A negative error code may be returned in case of parsing error. If the certificate does not contain the basicConstraints extension GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.

gnutls_x509_crt_get_crl_dist_points

Function: int gnutls_x509_crt_get_crl_dist_points (gnutls_x509_crt_t cert, unsigned int seq, void * ret, size_t * ret_size, unsigned int * reason_flags, unsigned int * critical)

cert: should contain a gnutls_x509_crt_t structure

seq: specifies the sequence number of the distribution point (0 for the first one, 1 for the second etc.)

ret: is the place where the distribution point will be copied to

ret_size: holds the size of ret.

reason_flags: Revocation reasons flags.

critical: will be non (0) if the extension is marked as critical (may be null)

This function retrieves the CRL distribution points (2.5.29.31), contained in the given certificate in the X509v3 Certificate Extensions.

reason_flags should be an ORed sequence of GNUTLS_CRL_REASON_UNUSED , GNUTLS_CRL_REASON_KEY_COMPROMISE , GNUTLS_CRL_REASON_CA_COMPROMISE , GNUTLS_CRL_REASON_AFFILIATION_CHANGED , GNUTLS_CRL_REASON_SUPERSEEDED , GNUTLS_CRL_REASON_CESSATION_OF_OPERATION , GNUTLS_CRL_REASON_CERTIFICATE_HOLD , GNUTLS_CRL_REASON_PRIVILEGE_WITHDRAWN , GNUTLS_CRL_REASON_AA_COMPROMISE , or (0) for all possible reasons.

Returns: GNUTLS_E_SHORT_MEMORY_BUFFER and updates ret_size if ret_size is not enough to hold the distribution point, or the type of the distribution point if everything was ok. The type is one of the enumerated gnutls_x509_subject_alt_name_t . If the certificate does not have an Alternative name with the specified sequence number then GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE is returned.

gnutls_x509_crt_get_dn

Function: int gnutls_x509_crt_get_dn (gnutls_x509_crt_t cert, char * buf, size_t * buf_size)

cert: should contain a gnutls_x509_crt_t structure

buf: a pointer to a structure to hold the name (may be null)

buf_size: initially holds the size of buf

This function will copy the name of the Certificate in the provided buffer. The name will be in the form "C=xxxx,O=yyyy,CN=zzzz" as described in RFC4514. The output string will be ASCII or UTF-8 encoded, depending on the certificate data.

If buf is null then only the size will be filled.

Returns: GNUTLS_E_SHORT_MEMORY_BUFFER if the provided buffer is not long enough, and in that case the buf_size will be updated with the required size. On success 0 is returned.

gnutls_x509_crt_get_dn_by_oid

Function: int gnutls_x509_crt_get_dn_by_oid (gnutls_x509_crt_t cert, const char * oid, int indx, unsigned int raw_flag, void * buf, size_t * buf_size)

cert: should contain a gnutls_x509_crt_t structure

oid: holds an Object Identified in null terminated string

indx: In case multiple same OIDs exist in the RDN, this specifies which to send. Use (0) to get the first one.

raw_flag: If non (0) returns the raw DER data of the DN part.

buf: a pointer where the DN part will be copied (may be null).

buf_size: initially holds the size of buf

This function will extract the part of the name of the Certificate subject specified by the given OID. The output, if the raw flag is not used, will be encoded as described in RFC4514. Thus a string that is ASCII or UTF-8 encoded, depending on the certificate data.

Some helper macros with popular OIDs can be found in gnutls/x509.h If raw flag is (0), this function will only return known OIDs as text. Other OIDs will be DER encoded, as described in RFC4514 – in hex format with a ’#’ prefix. You can check about known OIDs using gnutls_x509_dn_oid_known() .

If buf is null then only the size will be filled. If the raw_flag is not specified the output is always null terminated, although the buf_size will not include the null character.

Returns: GNUTLS_E_SHORT_MEMORY_BUFFER if the provided buffer is not long enough, and in that case the *buf_size will be updated with the required size. On success 0 is returned.

gnutls_x509_crt_get_dn_oid

Function: int gnutls_x509_crt_get_dn_oid (gnutls_x509_crt_t cert, int indx, void * oid, size_t * oid_size)

cert: should contain a gnutls_x509_crt_t structure

indx: This specifies which OID to return. Use (0) to get the first one.

oid: a pointer to a buffer to hold the OID (may be null)

oid_size: initially holds the size of oid

This function will extract the OIDs of the name of the Certificate subject specified by the given index.

If oid is null then only the size will be filled. The oid returned will be null terminated, although oid_size will not account for the trailing null.

Returns: GNUTLS_E_SHORT_MEMORY_BUFFER if the provided buffer is not long enough, and in that case the oid_size will be updated with the required size. On success 0 is returned.

gnutls_x509_crt_get_expiration_time

Function: time_t gnutls_x509_crt_get_expiration_time (gnutls_x509_crt_t cert)

cert: should contain a gnutls_x509_crt_t structure

This function will return the time this Certificate was or will be expired.

Returns: expiration time, or (time_t)-1 on error.

gnutls_x509_crt_get_extension_by_oid

Function: int gnutls_x509_crt_get_extension_by_oid (gnutls_x509_crt_t cert, const char * oid, int indx, void * buf, size_t * buf_size, unsigned int * critical)

cert: should contain a gnutls_x509_crt_t structure

oid: holds an Object Identified in null terminated string

indx: In case multiple same OIDs exist in the extensions, this specifies which to send. Use (0) to get the first one.

buf: a pointer to a structure to hold the name (may be null)

buf_size: initially holds the size of buf

critical: will be non (0) if the extension is marked as critical

This function will return the extension specified by the OID in the certificate. The extensions will be returned as binary data DER encoded, in the provided buffer.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned. If the certificate does not contain the specified extension GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.

gnutls_x509_crt_get_extension_data

Function: int gnutls_x509_crt_get_extension_data (gnutls_x509_crt_t cert, int indx, void * data, size_t * sizeof_data)

cert: should contain a gnutls_x509_crt_t structure

indx: Specifies which extension OID to send. Use (0) to get the first one.

data: a pointer to a structure to hold the data (may be null)

sizeof_data: initially holds the size of oid

This function will return the requested extension data in the certificate. The extension data will be stored as a string in the provided buffer.

Use gnutls_x509_crt_get_extension_info() to extract the OID and critical flag. Use gnutls_x509_crt_get_extension_by_oid() instead, if you want to get data indexed by the extension OID rather than sequence.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned. If you have reached the last extension available GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.

gnutls_x509_crt_get_extension_info

Function: int gnutls_x509_crt_get_extension_info (gnutls_x509_crt_t cert, int indx, void * oid, size_t * oid_size, unsigned int * critical)

cert: should contain a gnutls_x509_crt_t structure

indx: Specifies which extension OID to send. Use (0) to get the first one.

oid: a pointer to a structure to hold the OID

oid_size: initially holds the maximum size of oid , on return holds actual size of oid .

critical: output variable with critical flag, may be NULL.

This function will return the requested extension OID in the certificate, and the critical flag for it. The extension OID will be stored as a string in the provided buffer. Use gnutls_x509_crt_get_extension_data() to extract the data.

If the buffer provided is not long enough to hold the output, then oid_size is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will be returned. The oid returned will be null terminated, although oid_size will not account for the trailing null.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned. If you have reached the last extension available GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.

gnutls_x509_crt_get_extension_oid

Function: int gnutls_x509_crt_get_extension_oid (gnutls_x509_crt_t cert, int indx, void * oid, size_t * oid_size)

cert: should contain a gnutls_x509_crt_t structure

indx: Specifies which extension OID to send. Use (0) to get the first one.

oid: a pointer to a structure to hold the OID (may be null)

oid_size: initially holds the size of oid

This function will return the requested extension OID in the certificate. The extension OID will be stored as a string in the provided buffer.

The oid returned will be null terminated, although oid_size will not account for the trailing null.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned. If you have reached the last extension available GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.

gnutls_x509_crt_get_fingerprint

Function: int gnutls_x509_crt_get_fingerprint (gnutls_x509_crt_t cert, gnutls_digest_algorithm_t algo, void * buf, size_t * buf_size)

cert: should contain a gnutls_x509_crt_t structure

algo: is a digest algorithm

buf: a pointer to a structure to hold the fingerprint (may be null)

buf_size: initially holds the size of buf

This function will calculate and copy the certificate’s fingerprint in the provided buffer.

If the buffer is null then only the size will be filled.

Returns: GNUTLS_E_SHORT_MEMORY_BUFFER if the provided buffer is not long enough, and in that case the *buf_size will be updated with the required size. On success 0 is returned.

gnutls_x509_crt_get_issuer

Function: int gnutls_x509_crt_get_issuer (gnutls_x509_crt_t cert, gnutls_x509_dn_t * dn)

cert: should contain a gnutls_x509_crt_t structure

dn: output variable with pointer to uint8_t DN

Return the Certificate’s Issuer DN as an uint8_t data type. You may use gnutls_x509_dn_get_rdn_ava() to decode the DN.

Note that dn should be treated as constant. Because points into the cert object, you may not deallocate cert and continue to access dn .

Returns: Returns 0 on success, or an error code.

gnutls_x509_crt_get_issuer_alt_name

Function: int gnutls_x509_crt_get_issuer_alt_name (gnutls_x509_crt_t cert, unsigned int seq, void * ian, size_t * ian_size, unsigned int * critical)

cert: should contain a gnutls_x509_crt_t structure

seq: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)

ian: is the place where the alternative name will be copied to

ian_size: holds the size of ian.

critical: will be non (0) if the extension is marked as critical (may be null)

This function retrieves the Issuer Alternative Name (2.5.29.18), contained in the given certificate in the X509v3 Certificate Extensions.

When the SAN type is otherName, it will extract the data in the otherName’s value field, and GNUTLS_SAN_OTHERNAME is returned. You may use gnutls_x509_crt_get_subject_alt_othername_oid() to get the corresponding OID and the "virtual" SAN types (e.g., GNUTLS_SAN_OTHERNAME_XMPP ).

If an otherName OID is known, the data will be decoded. Otherwise the returned data will be DER encoded, and you will have to decode it yourself. Currently, only the RFC 3920 id-on-xmppAddr Issuer AltName is recognized.

Returns: the alternative issuer name type on success, one of the enumerated gnutls_x509_subject_alt_name_t . It will return GNUTLS_E_SHORT_MEMORY_BUFFER if ian_size is not large enough to hold the value. In that case ian_size will be updated with the required size. If the certificate does not have an Alternative name with the specified sequence number then GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE is returned.

Since: 2.10.0

gnutls_x509_crt_get_issuer_alt_name2

Function: int gnutls_x509_crt_get_issuer_alt_name2 (gnutls_x509_crt_t cert, unsigned int seq, void * ian, size_t * ian_size, unsigned int * ian_type, unsigned int * critical)

cert: should contain a gnutls_x509_crt_t structure

seq: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)

ian: is the place where the alternative name will be copied to

ian_size: holds the size of ret.

ian_type: holds the type of the alternative name (one of gnutls_x509_subject_alt_name_t).

critical: will be non (0) if the extension is marked as critical (may be null)

This function will return the alternative names, contained in the given certificate. It is the same as gnutls_x509_crt_get_issuer_alt_name() except for the fact that it will return the type of the alternative name in ian_type even if the function fails for some reason (i.e. the buffer provided is not enough).

Returns: the alternative issuer name type on success, one of the enumerated gnutls_x509_subject_alt_name_t . It will return GNUTLS_E_SHORT_MEMORY_BUFFER if ian_size is not large enough to hold the value. In that case ian_size will be updated with the required size. If the certificate does not have an Alternative name with the specified sequence number then GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE is returned.

Since: 2.10.0

gnutls_x509_crt_get_issuer_alt_othername_oid

Function: int gnutls_x509_crt_get_issuer_alt_othername_oid (gnutls_x509_crt_t cert, unsigned int seq, void * ret, size_t * ret_size)

cert: should contain a gnutls_x509_crt_t structure

seq: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)

ret: is the place where the otherName OID will be copied to

ret_size: holds the size of ret.

This function will extract the type OID of an otherName Subject Alternative Name, contained in the given certificate, and return the type as an enumerated element.

If oid is null then only the size will be filled. The oid returned will be null terminated, although oid_size will not account for the trailing null.

This function is only useful if gnutls_x509_crt_get_issuer_alt_name() returned GNUTLS_SAN_OTHERNAME .

Returns: the alternative issuer name type on success, one of the enumerated gnutls_x509_subject_alt_name_t. For supported OIDs, it will return one of the virtual (GNUTLS_SAN_OTHERNAME_*) types, e.g. GNUTLS_SAN_OTHERNAME_XMPP , and GNUTLS_SAN_OTHERNAME for unknown OIDs. It will return GNUTLS_E_SHORT_MEMORY_BUFFER if ret_size is not large enough to hold the value. In that case ret_size will be updated with the required size. If the certificate does not have an Alternative name with the specified sequence number and with the otherName type then GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE is returned.

Since: 2.10.0

gnutls_x509_crt_get_issuer_dn

Function: int gnutls_x509_crt_get_issuer_dn (gnutls_x509_crt_t cert, char * buf, size_t * buf_size)

cert: should contain a gnutls_x509_crt_t structure

buf: a pointer to a structure to hold the name (may be null)

buf_size: initially holds the size of buf

This function will copy the name of the Certificate issuer in the provided buffer. The name will be in the form "C=xxxx,O=yyyy,CN=zzzz" as described in RFC4514. The output string will be ASCII or UTF-8 encoded, depending on the certificate data.

If buf is null then only the size will be filled.

Returns: GNUTLS_E_SHORT_MEMORY_BUFFER if the provided buffer is not long enough, and in that case the buf_size will be updated with the required size. On success 0 is returned.

gnutls_x509_crt_get_issuer_dn_by_oid

Function: int gnutls_x509_crt_get_issuer_dn_by_oid (gnutls_x509_crt_t cert, const char * oid, int indx, unsigned int raw_flag, void * buf, size_t * buf_size)

cert: should contain a gnutls_x509_crt_t structure

oid: holds an Object Identified in null terminated string

indx: In case multiple same OIDs exist in the RDN, this specifies which to send. Use (0) to get the first one.

raw_flag: If non (0) returns the raw DER data of the DN part.

buf: a pointer to a structure to hold the name (may be null)

buf_size: initially holds the size of buf

This function will extract the part of the name of the Certificate issuer specified by the given OID. The output, if the raw flag is not used, will be encoded as described in RFC4514. Thus a string that is ASCII or UTF-8 encoded, depending on the certificate data.

Some helper macros with popular OIDs can be found in gnutls/x509.h If raw flag is (0), this function will only return known OIDs as text. Other OIDs will be DER encoded, as described in RFC4514 – in hex format with a ’#’ prefix. You can check about known OIDs using gnutls_x509_dn_oid_known() .

If buf is null then only the size will be filled. If the raw_flag is not specified the output is always null terminated, although the buf_size will not include the null character.

Returns: GNUTLS_E_SHORT_MEMORY_BUFFER if the provided buffer is not long enough, and in that case the buf_size will be updated with the required size. On success 0 is returned.

gnutls_x509_crt_get_issuer_dn_oid

Function: int gnutls_x509_crt_get_issuer_dn_oid (gnutls_x509_crt_t cert, int indx, void * oid, size_t * oid_size)

cert: should contain a gnutls_x509_crt_t structure

indx: This specifies which OID to return. Use (0) to get the first one.

oid: a pointer to a buffer to hold the OID (may be null)

oid_size: initially holds the size of oid

This function will extract the OIDs of the name of the Certificate issuer specified by the given index.

If oid is null then only the size will be filled. The oid returned will be null terminated, although oid_size will not account for the trailing null.

Returns: GNUTLS_E_SHORT_MEMORY_BUFFER if the provided buffer is not long enough, and in that case the oid_size will be updated with the required size. On success 0 is returned.

gnutls_x509_crt_get_issuer_unique_id

Function: int gnutls_x509_crt_get_issuer_unique_id (gnutls_x509_crt_t crt, char * buf, size_t * buf_size)

crt: Holds the certificate

buf: user allocated memory buffer, will hold the unique id

buf_size: size of user allocated memory buffer (on input), will hold actual size of the unique ID on return.

This function will extract the issuerUniqueID value (if present) for the given certificate.

If the user allocated memory buffer is not large enough to hold the full subjectUniqueID, then a GNUTLS_E_SHORT_MEMORY_BUFFER error will be returned, and buf_size will be set to the actual length.

Returns: GNUTLS_E_SUCCESS on success, otherwise a negative error code.

Since: 2.12.0

gnutls_x509_crt_get_key_id

Function: int gnutls_x509_crt_get_key_id (gnutls_x509_crt_t crt, unsigned int flags, unsigned char * output_data, size_t * output_data_size)

crt: Holds the certificate

flags: should be 0 for now

output_data: will contain the key ID

output_data_size: holds the size of output_data (and will be replaced by the actual size of parameters)

This function will return a unique ID the depends on the public key parameters. This ID can be used in checking whether a certificate corresponds to the given private key.

If the buffer provided is not long enough to hold the output, then *output_data_size is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will be returned. The output will normally be a SHA-1 hash output, which is 20 bytes.

Returns: In case of failure a negative error code will be returned, and 0 on success.

gnutls_x509_crt_get_key_purpose_oid

Function: int gnutls_x509_crt_get_key_purpose_oid (gnutls_x509_crt_t cert, int indx, void * oid, size_t * oid_size, unsigned int * critical)

cert: should contain a gnutls_x509_crt_t structure

indx: This specifies which OID to return. Use (0) to get the first one.

oid: a pointer to a buffer to hold the OID (may be null)

oid_size: initially holds the size of oid

critical: output flag to indicate criticality of extension

This function will extract the key purpose OIDs of the Certificate specified by the given index. These are stored in the Extended Key Usage extension (2.5.29.37) See the GNUTLS_KP_* definitions for human readable names.

If oid is null then only the size will be filled. The oid returned will be null terminated, although oid_size will not account for the trailing null.

Returns: GNUTLS_E_SHORT_MEMORY_BUFFER if the provided buffer is not long enough, and in that case the *oid_size will be updated with the required size. On success 0 is returned.

gnutls_x509_crt_get_key_usage

Function: int gnutls_x509_crt_get_key_usage (gnutls_x509_crt_t cert, unsigned int * key_usage, unsigned int * critical)

cert: should contain a gnutls_x509_crt_t structure

key_usage: where the key usage bits will be stored

critical: will be non (0) if the extension is marked as critical

This function will return certificate’s key usage, by reading the keyUsage X.509 extension (2.5.29.15). The key usage value will ORed values of the: GNUTLS_KEY_DIGITAL_SIGNATURE , GNUTLS_KEY_NON_REPUDIATION , GNUTLS_KEY_KEY_ENCIPHERMENT , GNUTLS_KEY_DATA_ENCIPHERMENT , GNUTLS_KEY_KEY_AGREEMENT , GNUTLS_KEY_KEY_CERT_SIGN , GNUTLS_KEY_CRL_SIGN , GNUTLS_KEY_ENCIPHER_ONLY , GNUTLS_KEY_DECIPHER_ONLY .

Returns: the certificate key usage, or a negative error code in case of parsing error. If the certificate does not contain the keyUsage extension GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.

gnutls_x509_crt_get_pk_algorithm

Function: int gnutls_x509_crt_get_pk_algorithm (gnutls_x509_crt_t cert, unsigned int * bits)

cert: should contain a gnutls_x509_crt_t structure

bits: if bits is non null it will hold the size of the parameters’ in bits

This function will return the public key algorithm of an X.509 certificate.

If bits is non null, it should have enough size to hold the parameters size in bits. For RSA the bits returned is the modulus. For DSA the bits returned are of the public exponent.

Returns: a member of the gnutls_pk_algorithm_t enumeration on success, or a negative error code on error.

gnutls_x509_crt_get_pk_dsa_raw

Function: int gnutls_x509_crt_get_pk_dsa_raw (gnutls_x509_crt_t crt, gnutls_datum_t * p, gnutls_datum_t * q, gnutls_datum_t * g, gnutls_datum_t * y)

crt: Holds the certificate

p: will hold the p

q: will hold the q

g: will hold the g

y: will hold the y

This function will export the DSA public key’s parameters found in the given certificate. The new parameters will be allocated using gnutls_malloc() and will be stored in the appropriate datum.

Returns: GNUTLS_E_SUCCESS on success, otherwise a negative error code.

gnutls_x509_crt_get_pk_rsa_raw

Function: int gnutls_x509_crt_get_pk_rsa_raw (gnutls_x509_crt_t crt, gnutls_datum_t * m, gnutls_datum_t * e)

crt: Holds the certificate

m: will hold the modulus

e: will hold the public exponent

This function will export the RSA public key’s parameters found in the given structure. The new parameters will be allocated using gnutls_malloc() and will be stored in the appropriate datum.

Returns: GNUTLS_E_SUCCESS on success, otherwise a negative error code.

gnutls_x509_crt_get_private_key_usage_period

Function: int gnutls_x509_crt_get_private_key_usage_period (gnutls_x509_crt_t cert, time_t* activation, time_t* expiration, unsigned int * critical)

cert: should contain a gnutls_x509_crt_t structure

activation: The activation time

expiration: The expiration time

critical: the extension status

This function will return the expiration and activation times of the private key of the certificate. It relies on the PKIX extension 2.5.29.16 being present.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE if the extension is not present, otherwise a negative error value.

gnutls_x509_crt_get_proxy

Function: int gnutls_x509_crt_get_proxy (gnutls_x509_crt_t cert, unsigned int * critical, int * pathlen, char ** policyLanguage, char ** policy, size_t * sizeof_policy)

cert: should contain a gnutls_x509_crt_t structure

critical: will be non (0) if the extension is marked as critical

pathlen: pointer to output integer indicating path length (may be NULL), non-negative error codes indicate a present pCPathLenConstraint field and the actual value, -1 indicate that the field is absent.

policyLanguage: output variable with OID of policy language

policy: output variable with policy data

sizeof_policy: output variable size of policy data

This function will get information from a proxy certificate. It reads the ProxyCertInfo X.509 extension (1.3.6.1.5.5.7.1.14).

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

gnutls_x509_crt_get_raw_dn

Function: int gnutls_x509_crt_get_raw_dn (gnutls_x509_crt_t cert, gnutls_datum_t * start)

cert: should contain a gnutls_x509_crt_t structure

start: will hold the starting point of the DN

This function will return a pointer to the DER encoded DN structure and the length.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value. or a negative error code on error.

gnutls_x509_crt_get_raw_issuer_dn

Function: int gnutls_x509_crt_get_raw_issuer_dn (gnutls_x509_crt_t cert, gnutls_datum_t * start)

cert: should contain a gnutls_x509_crt_t structure

start: will hold the starting point of the DN

This function will return a pointer to the DER encoded DN structure and the length.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.or a negative error code on error.

gnutls_x509_crt_get_serial

Function: int gnutls_x509_crt_get_serial (gnutls_x509_crt_t cert, void * result, size_t * result_size)

cert: should contain a gnutls_x509_crt_t structure

result: The place where the serial number will be copied

result_size: Holds the size of the result field.

This function will return the X.509 certificate’s serial number. This is obtained by the X509 Certificate serialNumber field. Serial is not always a 32 or 64bit number. Some CAs use large serial numbers, thus it may be wise to handle it as something uint8_t.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crt_get_signature

Function: int gnutls_x509_crt_get_signature (gnutls_x509_crt_t cert, char * sig, size_t * sizeof_sig)

cert: should contain a gnutls_x509_crt_t structure

sig: a pointer where the signature part will be copied (may be null).

sizeof_sig: initially holds the size of sig

This function will extract the signature field of a certificate.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value. and a negative error code on error.

gnutls_x509_crt_get_signature_algorithm

Function: int gnutls_x509_crt_get_signature_algorithm (gnutls_x509_crt_t cert)

cert: should contain a gnutls_x509_crt_t structure

This function will return a value of the gnutls_sign_algorithm_t enumeration that is the signature algorithm that has been used to sign this certificate.

Returns: a gnutls_sign_algorithm_t value, or a negative error code on error.

gnutls_x509_crt_get_subject

Function: int gnutls_x509_crt_get_subject (gnutls_x509_crt_t cert, gnutls_x509_dn_t * dn)

cert: should contain a gnutls_x509_crt_t structure

dn: output variable with pointer to uint8_t DN.

Return the Certificate’s Subject DN as an uint8_t data type. You may use gnutls_x509_dn_get_rdn_ava() to decode the DN.

Note that dn should be treated as constant. Because points into the cert object, you may not deallocate cert and continue to access dn .

Returns: Returns 0 on success, or an error code.

gnutls_x509_crt_get_subject_alt_name

Function: int gnutls_x509_crt_get_subject_alt_name (gnutls_x509_crt_t cert, unsigned int seq, void * san, size_t * san_size, unsigned int * critical)

cert: should contain a gnutls_x509_crt_t structure

seq: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)

san: is the place where the alternative name will be copied to

san_size: holds the size of san.

critical: will be non (0) if the extension is marked as critical (may be null)

This function retrieves the Alternative Name (2.5.29.17), contained in the given certificate in the X509v3 Certificate Extensions.

When the SAN type is otherName, it will extract the data in the otherName’s value field, and GNUTLS_SAN_OTHERNAME is returned. You may use gnutls_x509_crt_get_subject_alt_othername_oid() to get the corresponding OID and the "virtual" SAN types (e.g., GNUTLS_SAN_OTHERNAME_XMPP ).

If an otherName OID is known, the data will be decoded. Otherwise the returned data will be DER encoded, and you will have to decode it yourself. Currently, only the RFC 3920 id-on-xmppAddr SAN is recognized.

Returns: the alternative subject name type on success, one of the enumerated gnutls_x509_subject_alt_name_t . It will return GNUTLS_E_SHORT_MEMORY_BUFFER if san_size is not large enough to hold the value. In that case san_size will be updated with the required size. If the certificate does not have an Alternative name with the specified sequence number then GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE is returned.

gnutls_x509_crt_get_subject_alt_name2

Function: int gnutls_x509_crt_get_subject_alt_name2 (gnutls_x509_crt_t cert, unsigned int seq, void * san, size_t * san_size, unsigned int * san_type, unsigned int * critical)

cert: should contain a gnutls_x509_crt_t structure

seq: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)

san: is the place where the alternative name will be copied to

san_size: holds the size of ret.

san_type: holds the type of the alternative name (one of gnutls_x509_subject_alt_name_t).

critical: will be non (0) if the extension is marked as critical (may be null)

This function will return the alternative names, contained in the given certificate. It is the same as gnutls_x509_crt_get_subject_alt_name() except for the fact that it will return the type of the alternative name in san_type even if the function fails for some reason (i.e. the buffer provided is not enough).

Returns: the alternative subject name type on success, one of the enumerated gnutls_x509_subject_alt_name_t . It will return GNUTLS_E_SHORT_MEMORY_BUFFER if san_size is not large enough to hold the value. In that case san_size will be updated with the required size. If the certificate does not have an Alternative name with the specified sequence number then GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE is returned.

gnutls_x509_crt_get_subject_alt_othername_oid

Function: int gnutls_x509_crt_get_subject_alt_othername_oid (gnutls_x509_crt_t cert, unsigned int seq, void * oid, size_t * oid_size)

cert: should contain a gnutls_x509_crt_t structure

seq: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)

oid: is the place where the otherName OID will be copied to

oid_size: holds the size of ret.

This function will extract the type OID of an otherName Subject Alternative Name, contained in the given certificate, and return the type as an enumerated element.

This function is only useful if gnutls_x509_crt_get_subject_alt_name() returned GNUTLS_SAN_OTHERNAME .

If oid is null then only the size will be filled. The oid returned will be null terminated, although oid_size will not account for the trailing null.

Returns: the alternative subject name type on success, one of the enumerated gnutls_x509_subject_alt_name_t. For supported OIDs, it will return one of the virtual (GNUTLS_SAN_OTHERNAME_*) types, e.g. GNUTLS_SAN_OTHERNAME_XMPP , and GNUTLS_SAN_OTHERNAME for unknown OIDs. It will return GNUTLS_E_SHORT_MEMORY_BUFFER if ian_size is not large enough to hold the value. In that case ian_size will be updated with the required size. If the certificate does not have an Alternative name with the specified sequence number and with the otherName type then GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE is returned.

gnutls_x509_crt_get_subject_key_id

Function: int gnutls_x509_crt_get_subject_key_id (gnutls_x509_crt_t cert, void * ret, size_t * ret_size, unsigned int * critical)

cert: should contain a gnutls_x509_crt_t structure

ret: The place where the identifier will be copied

ret_size: Holds the size of the result field.

critical: will be non (0) if the extension is marked as critical (may be null)

This function will return the X.509v3 certificate’s subject key identifier. This is obtained by the X.509 Subject Key identifier extension field (2.5.29.14).

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE if the extension is not present, otherwise a negative error value.

gnutls_x509_crt_get_subject_unique_id

Function: int gnutls_x509_crt_get_subject_unique_id (gnutls_x509_crt_t crt, char * buf, size_t * buf_size)

crt: Holds the certificate

buf: user allocated memory buffer, will hold the unique id

buf_size: size of user allocated memory buffer (on input), will hold actual size of the unique ID on return.

This function will extract the subjectUniqueID value (if present) for the given certificate.

If the user allocated memory buffer is not large enough to hold the full subjectUniqueID, then a GNUTLS_E_SHORT_MEMORY_BUFFER error will be returned, and buf_size will be set to the actual length.

Returns: GNUTLS_E_SUCCESS on success, otherwise a negative error code.

gnutls_x509_crt_get_version

Function: int gnutls_x509_crt_get_version (gnutls_x509_crt_t cert)

cert: should contain a gnutls_x509_crt_t structure

This function will return the version of the specified Certificate.

Returns: version of certificate, or a negative error code on error.

gnutls_x509_crt_import

Function: int gnutls_x509_crt_import (gnutls_x509_crt_t cert, const gnutls_datum_t * data, gnutls_x509_crt_fmt_t format)

cert: The structure to store the parsed certificate.

data: The DER or PEM encoded certificate.

format: One of DER or PEM

This function will convert the given DER or PEM encoded Certificate to the native gnutls_x509_crt_t format. The output will be stored in cert .

If the Certificate is PEM encoded it should have a header of "X509 CERTIFICATE", or "CERTIFICATE".

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crt_init

Function: int gnutls_x509_crt_init (gnutls_x509_crt_t * cert)

cert: The structure to be initialized

This function will initialize an X.509 certificate structure.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crt_list_import

Function: int gnutls_x509_crt_list_import (gnutls_x509_crt_t * certs, unsigned int * cert_max, const gnutls_datum_t * data, gnutls_x509_crt_fmt_t format, unsigned int flags)

certs: The structures to store the parsed certificate. Must not be initialized.

cert_max: Initially must hold the maximum number of certs. It will be updated with the number of certs available.

data: The PEM encoded certificate.

format: One of DER or PEM.

flags: must be (0) or an OR’d sequence of gnutls_certificate_import_flags.

This function will convert the given PEM encoded certificate list to the native gnutls_x509_crt_t format. The output will be stored in certs . They will be automatically initialized.

The flag GNUTLS_X509_CRT_LIST_IMPORT_FAIL_IF_EXCEED will cause import to fail if the certificates in the provided buffer are more than the available structures. The GNUTLS_X509_CRT_LIST_FAIL_IF_UNSORTED flag will cause the function to fail if the provided list is not sorted from subject to issuer.

If the Certificate is PEM encoded it should have a header of "X509 CERTIFICATE", or "CERTIFICATE".

Returns: the number of certificates read or a negative error value.

gnutls_x509_crt_list_import2

Function: int gnutls_x509_crt_list_import2 (gnutls_x509_crt_t ** certs, unsigned int * size, const gnutls_datum_t * data, gnutls_x509_crt_fmt_t format, unsigned int flags)

certs: The structures to store the parsed certificate. Must not be initialized.

size: It will contain the size of the list.

data: The PEM encoded certificate.

format: One of DER or PEM.

flags: must be (0) or an OR’d sequence of gnutls_certificate_import_flags.

This function will convert the given PEM encoded certificate list to the native gnutls_x509_crt_t format. The output will be stored in certs . They will be automatically initialized.

If the Certificate is PEM encoded it should have a header of "X509 CERTIFICATE", or "CERTIFICATE".

Returns: the number of certificates read or a negative error value.

Since: 3.0

gnutls_x509_crt_list_verify

Function: int gnutls_x509_crt_list_verify (const gnutls_x509_crt_t * cert_list, int cert_list_length, const gnutls_x509_crt_t * CA_list, int CA_list_length, const gnutls_x509_crl_t * CRL_list, int CRL_list_length, unsigned int flags, unsigned int * verify)

cert_list: is the certificate list to be verified

cert_list_length: holds the number of certificate in cert_list

CA_list: is the CA list which will be used in verification

CA_list_length: holds the number of CA certificate in CA_list

CRL_list: holds a list of CRLs.

CRL_list_length: the length of CRL list.

flags: Flags that may be used to change the verification algorithm. Use OR of the gnutls_certificate_verify_flags enumerations.

verify: will hold the certificate verification output.

This function will try to verify the given certificate list and return its status. If no flags are specified (0), this function will use the basicConstraints (2.5.29.19) PKIX extension. This means that only a certificate authority is allowed to sign a certificate.

You must also check the peer’s name in order to check if the verified certificate belongs to the actual peer.

The certificate verification output will be put in verify and will be one or more of the gnutls_certificate_status_t enumerated elements bitwise or’d. For a more detailed verification status use gnutls_x509_crt_verify() per list element.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crt_print

Function: int gnutls_x509_crt_print (gnutls_x509_crt_t cert, gnutls_certificate_print_formats_t format, gnutls_datum_t * out)

cert: The structure to be printed

format: Indicate the format to use

out: Newly allocated datum with (0) terminated string.

This function will pretty print a X.509 certificate, suitable for display to a human.

If the format is GNUTLS_CRT_PRINT_FULL then all fields of the certificate will be output, on multiple lines. The GNUTLS_CRT_PRINT_ONELINE format will generate one line with some selected fields, which is useful for logging purposes.

The output out needs to be deallocate using gnutls_free() .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crt_set_activation_time

Function: int gnutls_x509_crt_set_activation_time (gnutls_x509_crt_t cert, time_t act_time)

cert: a certificate of type gnutls_x509_crt_t

act_time: The actual time

This function will set the time this Certificate was or will be activated.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crt_set_authority_info_access

Function: int gnutls_x509_crt_set_authority_info_access (gnutls_x509_crt_t crt, int what, gnutls_datum_t * data)

crt: Holds the certificate

what: what data to get, a gnutls_info_access_what_t type.

data: output data to be freed with gnutls_free() .

This function sets the Authority Information Access (AIA) extension, see RFC 5280 section 4.2.2.1 for more information.

The type of data stored in data is specified via what which should be gnutls_info_access_what_t values.

If what is GNUTLS_IA_OCSP_URI , data will hold the OCSP URI. If what is GNUTLS_IA_CAISSUERS_URI , data will hold the caIssuers URI.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 3.0

gnutls_x509_crt_set_authority_key_id

Function: int gnutls_x509_crt_set_authority_key_id (gnutls_x509_crt_t cert, const void * id, size_t id_size)

cert: a certificate of type gnutls_x509_crt_t

id: The key ID

id_size: Holds the size of the serial field.

This function will set the X.509 certificate’s authority key ID extension. Only the keyIdentifier field can be set with this function.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crt_set_basic_constraints

Function: int gnutls_x509_crt_set_basic_constraints (gnutls_x509_crt_t crt, unsigned int ca, int pathLenConstraint)

crt: a certificate of type gnutls_x509_crt_t

ca: true(1) or false(0). Depending on the Certificate authority status.

pathLenConstraint: non-negative error codes indicate maximum length of path, and negative error codes indicate that the pathLenConstraints field should not be present.

This function will set the basicConstraints certificate extension.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crt_set_ca_status

Function: int gnutls_x509_crt_set_ca_status (gnutls_x509_crt_t crt, unsigned int ca)

crt: a certificate of type gnutls_x509_crt_t

ca: true(1) or false(0). Depending on the Certificate authority status.

This function will set the basicConstraints certificate extension. Use gnutls_x509_crt_set_basic_constraints() if you want to control the pathLenConstraint field too.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crt_set_crl_dist_points

Function: int gnutls_x509_crt_set_crl_dist_points (gnutls_x509_crt_t crt, gnutls_x509_subject_alt_name_t type, const void * data_string, unsigned int reason_flags)

crt: a certificate of type gnutls_x509_crt_t

type: is one of the gnutls_x509_subject_alt_name_t enumerations

data_string: The data to be set

reason_flags: revocation reasons

This function will set the CRL distribution points certificate extension.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crt_set_crl_dist_points2

Function: int gnutls_x509_crt_set_crl_dist_points2 (gnutls_x509_crt_t crt, gnutls_x509_subject_alt_name_t type, const void * data, unsigned int data_size, unsigned int reason_flags)

crt: a certificate of type gnutls_x509_crt_t

type: is one of the gnutls_x509_subject_alt_name_t enumerations

data: The data to be set

data_size: The data size

reason_flags: revocation reasons

This function will set the CRL distribution points certificate extension.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.6.0

gnutls_x509_crt_set_crq

Function: int gnutls_x509_crt_set_crq (gnutls_x509_crt_t crt, gnutls_x509_crq_t crq)

crt: a certificate of type gnutls_x509_crt_t

crq: holds a certificate request

This function will set the name and public parameters as well as the extensions from the given certificate request to the certificate. Only RSA keys are currently supported.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crt_set_crq_extensions

Function: int gnutls_x509_crt_set_crq_extensions (gnutls_x509_crt_t crt, gnutls_x509_crq_t crq)

crt: a certificate of type gnutls_x509_crt_t

crq: holds a certificate request

This function will set extensions from the given request to the certificate.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.8.0

gnutls_x509_crt_set_dn_by_oid

Function: int gnutls_x509_crt_set_dn_by_oid (gnutls_x509_crt_t crt, const char * oid, unsigned int raw_flag, const void * name, unsigned int sizeof_name)

crt: a certificate of type gnutls_x509_crt_t

oid: holds an Object Identifier in a null terminated string

raw_flag: must be 0, or 1 if the data are DER encoded

name: a pointer to the name

sizeof_name: holds the size of name

This function will set the part of the name of the Certificate subject, specified by the given OID. The input string should be ASCII or UTF-8 encoded.

Some helper macros with popular OIDs can be found in gnutls/x509.h With this function you can only set the known OIDs. You can test for known OIDs using gnutls_x509_dn_oid_known() . For OIDs that are not known (by gnutls) you should properly DER encode your data, and call this function with raw_flag set.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crt_set_expiration_time

Function: int gnutls_x509_crt_set_expiration_time (gnutls_x509_crt_t cert, time_t exp_time)

cert: a certificate of type gnutls_x509_crt_t

exp_time: The actual time

This function will set the time this Certificate will expire.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crt_set_extension_by_oid

Function: int gnutls_x509_crt_set_extension_by_oid (gnutls_x509_crt_t crt, const char * oid, const void * buf, size_t sizeof_buf, unsigned int critical)

crt: a certificate of type gnutls_x509_crt_t

oid: holds an Object Identified in null terminated string

buf: a pointer to a DER encoded data

sizeof_buf: holds the size of buf

critical: should be non (0) if the extension is to be marked as critical

This function will set an the extension, by the specified OID, in the certificate. The extension data should be binary data DER encoded.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crt_set_issuer_dn_by_oid

Function: int gnutls_x509_crt_set_issuer_dn_by_oid (gnutls_x509_crt_t crt, const char * oid, unsigned int raw_flag, const void * name, unsigned int sizeof_name)

crt: a certificate of type gnutls_x509_crt_t

oid: holds an Object Identifier in a null terminated string

raw_flag: must be 0, or 1 if the data are DER encoded

name: a pointer to the name

sizeof_name: holds the size of name

This function will set the part of the name of the Certificate issuer, specified by the given OID. The input string should be ASCII or UTF-8 encoded.

Some helper macros with popular OIDs can be found in gnutls/x509.h With this function you can only set the known OIDs. You can test for known OIDs using gnutls_x509_dn_oid_known() . For OIDs that are not known (by gnutls) you should properly DER encode your data, and call this function with raw_flag set.

Normally you do not need to call this function, since the signing operation will copy the signer’s name as the issuer of the certificate.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crt_set_key

Function: int gnutls_x509_crt_set_key (gnutls_x509_crt_t crt, gnutls_x509_privkey_t key)

crt: a certificate of type gnutls_x509_crt_t

key: holds a private key

This function will set the public parameters from the given private key to the certificate. Only RSA keys are currently supported.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crt_set_key_purpose_oid

Function: int gnutls_x509_crt_set_key_purpose_oid (gnutls_x509_crt_t cert, const void * oid, unsigned int critical)

cert: a certificate of type gnutls_x509_crt_t

oid: a pointer to a null terminated string that holds the OID

critical: Whether this extension will be critical or not

This function will set the key purpose OIDs of the Certificate. These are stored in the Extended Key Usage extension (2.5.29.37) See the GNUTLS_KP_* definitions for human readable names.

Subsequent calls to this function will append OIDs to the OID list.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

gnutls_x509_crt_set_key_usage

Function: int gnutls_x509_crt_set_key_usage (gnutls_x509_crt_t crt, unsigned int usage)

crt: a certificate of type gnutls_x509_crt_t

usage: an ORed sequence of the GNUTLS_KEY_* elements.

This function will set the keyUsage certificate extension.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crt_set_private_key_usage_period

Function: int gnutls_x509_crt_set_private_key_usage_period (gnutls_x509_crt_t crt, time_t activation, time_t expiration)

crt: a certificate of type gnutls_x509_crt_t

activation: The activation time

expiration: The expiration time

This function will set the private key usage period extension (2.5.29.16).

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crt_set_proxy

Function: int gnutls_x509_crt_set_proxy (gnutls_x509_crt_t crt, int pathLenConstraint, const char * policyLanguage, const char * policy, size_t sizeof_policy)

crt: a certificate of type gnutls_x509_crt_t

pathLenConstraint: non-negative error codes indicate maximum length of path, and negative error codes indicate that the pathLenConstraints field should not be present.

policyLanguage: OID describing the language of policy .

policy: uint8_t byte array with policy language, can be NULL

sizeof_policy: size of policy .

This function will set the proxyCertInfo extension.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crt_set_proxy_dn

Function: int gnutls_x509_crt_set_proxy_dn (gnutls_x509_crt_t crt, gnutls_x509_crt_t eecrt, unsigned int raw_flag, const void * name, unsigned int sizeof_name)

crt: a gnutls_x509_crt_t structure with the new proxy cert

eecrt: the end entity certificate that will be issuing the proxy

raw_flag: must be 0, or 1 if the CN is DER encoded

name: a pointer to the CN name, may be NULL (but MUST then be added later)

sizeof_name: holds the size of name

This function will set the subject in crt to the end entity’s eecrt subject name, and add a single Common Name component name of size sizeof_name . This corresponds to the required proxy certificate naming style. Note that if name is NULL , you MUST set it later by using gnutls_x509_crt_set_dn_by_oid() or similar.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crt_set_serial

Function: int gnutls_x509_crt_set_serial (gnutls_x509_crt_t cert, const void * serial, size_t serial_size)

cert: a certificate of type gnutls_x509_crt_t

serial: The serial number

serial_size: Holds the size of the serial field.

This function will set the X.509 certificate’s serial number. Serial is not always a 32 or 64bit number. Some CAs use large serial numbers, thus it may be wise to handle it as something uint8_t.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crt_set_subject_alt_name

Function: int gnutls_x509_crt_set_subject_alt_name (gnutls_x509_crt_t crt, gnutls_x509_subject_alt_name_t type, const void * data, unsigned int data_size, unsigned int flags)

crt: a certificate of type gnutls_x509_crt_t

type: is one of the gnutls_x509_subject_alt_name_t enumerations

data: The data to be set

data_size: The size of data to be set

flags: GNUTLS_FSAN_SET to clear previous data or GNUTLS_FSAN_APPEND to append.

This function will set the subject alternative name certificate extension. It can set the following types:

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.6.0

gnutls_x509_crt_set_subject_alternative_name

Function: int gnutls_x509_crt_set_subject_alternative_name (gnutls_x509_crt_t crt, gnutls_x509_subject_alt_name_t                                               type, const char * data_string)

crt: a certificate of type gnutls_x509_crt_t

type: is one of the gnutls_x509_subject_alt_name_t enumerations

data_string: The data to be set, a (0) terminated string

This function will set the subject alternative name certificate extension. This function assumes that data can be expressed as a null terminated string.

The name of the function is unfortunate since it is incosistent with gnutls_x509_crt_get_subject_alt_name() .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crt_set_subject_key_id

Function: int gnutls_x509_crt_set_subject_key_id (gnutls_x509_crt_t cert, const void * id, size_t id_size)

cert: a certificate of type gnutls_x509_crt_t

id: The key ID

id_size: Holds the size of the serial field.

This function will set the X.509 certificate’s subject key ID extension.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crt_set_version

Function: int gnutls_x509_crt_set_version (gnutls_x509_crt_t crt, unsigned int version)

crt: a certificate of type gnutls_x509_crt_t

version: holds the version number. For X.509v1 certificates must be 1.

This function will set the version of the certificate. This must be one for X.509 version 1, and so on. Plain certificates without extensions must have version set to one.

To create well-formed certificates, you must specify version 3 if you use any certificate extensions. Extensions are created by functions such as gnutls_x509_crt_set_subject_alt_name() or gnutls_x509_crt_set_key_usage() .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crt_sign

Function: int gnutls_x509_crt_sign (gnutls_x509_crt_t crt, gnutls_x509_crt_t issuer, gnutls_x509_privkey_t issuer_key)

crt: a certificate of type gnutls_x509_crt_t

issuer: is the certificate of the certificate issuer

issuer_key: holds the issuer’s private key

This function is the same a gnutls_x509_crt_sign2() with no flags, and SHA1 as the hash algorithm.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crt_sign2

Function: int gnutls_x509_crt_sign2 (gnutls_x509_crt_t crt, gnutls_x509_crt_t issuer, gnutls_x509_privkey_t issuer_key, gnutls_digest_algorithm_t dig, unsigned int flags)

crt: a certificate of type gnutls_x509_crt_t

issuer: is the certificate of the certificate issuer

issuer_key: holds the issuer’s private key

dig: The message digest to use, GNUTLS_DIG_SHA1 is a safe choice

flags: must be 0

This function will sign the certificate with the issuer’s private key, and will copy the issuer’s information into the certificate.

This must be the last step in a certificate generation since all the previously set parameters are now signed.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crt_verify

Function: int gnutls_x509_crt_verify (gnutls_x509_crt_t cert, const gnutls_x509_crt_t * CA_list, int CA_list_length, unsigned int flags, unsigned int * verify)

cert: is the certificate to be verified

CA_list: is one certificate that is considered to be trusted one

CA_list_length: holds the number of CA certificate in CA_list

flags: Flags that may be used to change the verification algorithm. Use OR of the gnutls_certificate_verify_flags enumerations.

verify: will hold the certificate verification output.

This function will try to verify the given certificate and return its status.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_dn_deinit

Function: void gnutls_x509_dn_deinit (gnutls_x509_dn_t dn)

dn: a DN uint8_t object pointer.

This function deallocates the DN object as returned by gnutls_x509_dn_import() .

Since: 2.4.0

gnutls_x509_dn_export

Function: int gnutls_x509_dn_export (gnutls_x509_dn_t dn, gnutls_x509_crt_fmt_t format, void * output_data, size_t * output_data_size)

dn: Holds the uint8_t DN object

format: the format of output params. One of PEM or DER.

output_data: will contain a DN PEM or DER encoded

output_data_size: holds the size of output_data (and will be replaced by the actual size of parameters)

This function will export the DN to DER or PEM format.

If the buffer provided is not long enough to hold the output, then * output_data_size is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will be returned.

If the structure is PEM encoded, it will have a header of "BEGIN NAME".

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_dn_get_rdn_ava

Function: int gnutls_x509_dn_get_rdn_ava (gnutls_x509_dn_t dn, int irdn, int iava, gnutls_x509_ava_st * ava)

dn: input variable with uint8_t DN pointer

irdn: index of RDN

iava: index of AVA.

ava: Pointer to structure which will hold output information.

Get pointers to data within the DN.

Note that ava will contain pointers into the dn structure, so you should not modify any data or deallocate it. Note also that the DN in turn points into the original certificate structure, and thus you may not deallocate the certificate and continue to access dn .

Returns: Returns 0 on success, or an error code.

gnutls_x509_dn_import

Function: int gnutls_x509_dn_import (gnutls_x509_dn_t dn, const gnutls_datum_t * data)

dn: the structure that will hold the imported DN

data: should contain a DER encoded RDN sequence

This function parses an RDN sequence and stores the result to a gnutls_x509_dn_t structure. The structure must have been initialized with gnutls_x509_dn_init() . You may use gnutls_x509_dn_get_rdn_ava() to decode the DN.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.4.0

gnutls_x509_dn_init

Function: int gnutls_x509_dn_init (gnutls_x509_dn_t * dn)

dn: the object to be initialized

This function initializes a gnutls_x509_dn_t structure.

The object returned must be deallocated using gnutls_x509_dn_deinit() .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.4.0

gnutls_x509_dn_oid_known

Function: int gnutls_x509_dn_oid_known (const char * oid)

oid: holds an Object Identifier in a null terminated string

This function will inform about known DN OIDs. This is useful since functions like gnutls_x509_crt_set_dn_by_oid() use the information on known OIDs to properly encode their input. Object Identifiers that are not known are not encoded by these functions, and their input is stored directly into the ASN.1 structure. In that case of unknown OIDs, you have the responsibility of DER encoding your data.

Returns: 1 on known OIDs and 0 otherwise.

gnutls_x509_dn_oid_name

Function: const char* gnutls_x509_dn_oid_name (const char * oid, unsigned int flags)

oid: holds an Object Identifier in a null terminated string

flags: 0 or GNUTLS_X509_DN_OID_ *

This function will return the name of a known DN OID. If GNUTLS_X509_DN_OID_RETURN_OID is specified this function will return the given OID if no descriptive name has been found.

Returns: A null terminated string or NULL otherwise.

Since: 3.0

gnutls_x509_privkey_cpy

Function: int gnutls_x509_privkey_cpy (gnutls_x509_privkey_t dst, gnutls_x509_privkey_t src)

dst: The destination key, which should be initialized.

src: The source key

This function will copy a private key from source to destination key. Destination has to be initialized.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_privkey_deinit

Function: void gnutls_x509_privkey_deinit (gnutls_x509_privkey_t key)

key: The structure to be deinitialized

This function will deinitialize a private key structure.

gnutls_x509_privkey_export

Function: int gnutls_x509_privkey_export (gnutls_x509_privkey_t key, gnutls_x509_crt_fmt_t format, void * output_data, size_t * output_data_size)

key: Holds the key

format: the format of output params. One of PEM or DER.

output_data: will contain a private key PEM or DER encoded

output_data_size: holds the size of output_data (and will be replaced by the actual size of parameters)

This function will export the private key to a PKCS1 structure for RSA keys, or an integer sequence for DSA keys. The DSA keys are in the same format with the parameters used by openssl.

If the buffer provided is not long enough to hold the output, then * output_data_size is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will be returned.

If the structure is PEM encoded, it will have a header of "BEGIN RSA PRIVATE KEY".

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_privkey_export_dsa_raw

Function: int gnutls_x509_privkey_export_dsa_raw (gnutls_x509_privkey_t key, gnutls_datum_t * p, gnutls_datum_t * q, gnutls_datum_t * g, gnutls_datum_t * y, gnutls_datum_t * x)

key: a structure that holds the DSA parameters

p: will hold the p

q: will hold the q

g: will hold the g

y: will hold the y

x: will hold the x

This function will export the DSA private key’s parameters found in the given structure. The new parameters will be allocated using gnutls_malloc() and will be stored in the appropriate datum.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_privkey_export_ecc_raw

Function: int gnutls_x509_privkey_export_ecc_raw (gnutls_x509_privkey_t key, gnutls_ecc_curve_t * curve, gnutls_datum_t * x, gnutls_datum_t * y, gnutls_datum_t* k)

key: a structure that holds the rsa parameters

curve: will hold the curve

x: will hold the x coordinate

y: will hold the y coordinate

k: will hold the private key

This function will export the ECC private key’s parameters found in the given structure. The new parameters will be allocated using gnutls_malloc() and will be stored in the appropriate datum.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 3.0

gnutls_x509_privkey_export_pkcs8

Function: int gnutls_x509_privkey_export_pkcs8 (gnutls_x509_privkey_t key, gnutls_x509_crt_fmt_t format, const char * password, unsigned int flags, void * output_data, size_t * output_data_size)

key: Holds the key

format: the format of output params. One of PEM or DER.

password: the password that will be used to encrypt the key.

flags: an ORed sequence of gnutls_pkcs_encrypt_flags_t

output_data: will contain a private key PEM or DER encoded

output_data_size: holds the size of output_data (and will be replaced by the actual size of parameters)

This function will export the private key to a PKCS8 structure. Both RSA and DSA keys can be exported. For DSA keys we use PKCS 11 definitions. If the flags do not specify the encryption cipher, then the default 3DES (PBES2) will be used.

The password can be either ASCII or UTF-8 in the default PBES2 encryption schemas, or ASCII for the PKCS12 schemas.

If the buffer provided is not long enough to hold the output, then *output_data_size is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will be returned.

If the structure is PEM encoded, it will have a header of "BEGIN ENCRYPTED PRIVATE KEY" or "BEGIN PRIVATE KEY" if encryption is not used.

Returns: In case of failure a negative error code will be returned, and 0 on success.

gnutls_x509_privkey_export_rsa_raw

Function: int gnutls_x509_privkey_export_rsa_raw (gnutls_x509_privkey_t key, gnutls_datum_t * m, gnutls_datum_t * e, gnutls_datum_t * d, gnutls_datum_t * p, gnutls_datum_t * q, gnutls_datum_t * u)

key: a structure that holds the rsa parameters

m: will hold the modulus

e: will hold the public exponent

d: will hold the private exponent

p: will hold the first prime (p)

q: will hold the second prime (q)

u: will hold the coefficient

This function will export the RSA private key’s parameters found in the given structure. The new parameters will be allocated using gnutls_malloc() and will be stored in the appropriate datum.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_privkey_export_rsa_raw2

Function: int gnutls_x509_privkey_export_rsa_raw2 (gnutls_x509_privkey_t key, gnutls_datum_t * m, gnutls_datum_t * e, gnutls_datum_t * d, gnutls_datum_t * p, gnutls_datum_t * q, gnutls_datum_t * u, gnutls_datum_t * e1, gnutls_datum_t * e2)

key: a structure that holds the rsa parameters

m: will hold the modulus

e: will hold the public exponent

d: will hold the private exponent

p: will hold the first prime (p)

q: will hold the second prime (q)

u: will hold the coefficient

e1: will hold e1 = d mod (p-1)

e2: will hold e2 = d mod (q-1)

This function will export the RSA private key’s parameters found in the given structure. The new parameters will be allocated using gnutls_malloc() and will be stored in the appropriate datum.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.12.0

gnutls_x509_privkey_fix

Function: int gnutls_x509_privkey_fix (gnutls_x509_privkey_t key)

key: Holds the key

This function will recalculate the secondary parameters in a key. In RSA keys, this can be the coefficient and exponent1,2.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_privkey_generate

Function: int gnutls_x509_privkey_generate (gnutls_x509_privkey_t key, gnutls_pk_algorithm_t algo, unsigned int bits, unsigned int flags)

key: should contain a gnutls_x509_privkey_t structure

algo: is one of the algorithms in gnutls_pk_algorithm_t .

bits: the size of the modulus

flags: unused for now. Must be 0.

This function will generate a random private key. Note that this function must be called on an empty private key.

Do not set the number of bits directly, use gnutls_sec_param_to_pk_bits() .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_privkey_get_key_id

Function: int gnutls_x509_privkey_get_key_id (gnutls_x509_privkey_t key, unsigned int flags, unsigned char * output_data, size_t * output_data_size)

key: Holds the key

flags: should be 0 for now

output_data: will contain the key ID

output_data_size: holds the size of output_data (and will be replaced by the actual size of parameters)

This function will return a unique ID the depends on the public key parameters. This ID can be used in checking whether a certificate corresponds to the given key.

If the buffer provided is not long enough to hold the output, then * output_data_size is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will be returned. The output will normally be a SHA-1 hash output, which is 20 bytes.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_privkey_get_pk_algorithm

Function: int gnutls_x509_privkey_get_pk_algorithm (gnutls_x509_privkey_t key)

key: should contain a gnutls_x509_privkey_t structure

This function will return the public key algorithm of a private key.

Returns: a member of the gnutls_pk_algorithm_t enumeration on success, or a negative error code on error.

gnutls_x509_privkey_import

Function: int gnutls_x509_privkey_import (gnutls_x509_privkey_t key, const gnutls_datum_t * data, gnutls_x509_crt_fmt_t format)

key: The structure to store the parsed key

data: The DER or PEM encoded certificate.

format: One of DER or PEM

This function will convert the given DER or PEM encoded key to the native gnutls_x509_privkey_t format. The output will be stored in key .

If the key is PEM encoded it should have a header of "RSA PRIVATE KEY", or "DSA PRIVATE KEY".

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_privkey_import_dsa_raw

Function: int gnutls_x509_privkey_import_dsa_raw (gnutls_x509_privkey_t key, const gnutls_datum_t * p, const gnutls_datum_t * q, const gnutls_datum_t * g, const gnutls_datum_t * y, const gnutls_datum_t * x)

key: The structure to store the parsed key

p: holds the p

q: holds the q

g: holds the g

y: holds the y

x: holds the x

This function will convert the given DSA raw parameters to the native gnutls_x509_privkey_t format. The output will be stored in key .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_privkey_import_ecc_raw

Function: int gnutls_x509_privkey_import_ecc_raw (gnutls_x509_privkey_t key, gnutls_ecc_curve_t curve, const gnutls_datum_t * x, const gnutls_datum_t * y, const gnutls_datum_t * k)

key: The structure to store the parsed key

curve: holds the curve

x: holds the x

y: holds the y

k: holds the k

This function will convert the given elliptic curve parameters to the native gnutls_x509_privkey_t format. The output will be stored in key .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 3.0

gnutls_x509_privkey_import_pkcs8

Function: int gnutls_x509_privkey_import_pkcs8 (gnutls_x509_privkey_t key, const gnutls_datum_t * data, gnutls_x509_crt_fmt_t format, const char * password, unsigned int flags)

key: The structure to store the parsed key

data: The DER or PEM encoded key.

format: One of DER or PEM

password: the password to decrypt the key (if it is encrypted).

flags: 0 if encrypted or GNUTLS_PKCS_PLAIN if not encrypted.

This function will convert the given DER or PEM encoded PKCS8 2.0 encrypted key to the native gnutls_x509_privkey_t format. The output will be stored in key . Both RSA and DSA keys can be imported, and flags can only be used to indicate an unencrypted key.

The password can be either ASCII or UTF-8 in the default PBES2 encryption schemas, or ASCII for the PKCS12 schemas.

If the Certificate is PEM encoded it should have a header of "ENCRYPTED PRIVATE KEY", or "PRIVATE KEY". You only need to specify the flags if the key is DER encoded, since in that case the encryption status cannot be auto-detected.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_privkey_import_rsa_raw

Function: int gnutls_x509_privkey_import_rsa_raw (gnutls_x509_privkey_t key, const gnutls_datum_t * m, const gnutls_datum_t * e, const gnutls_datum_t * d, const gnutls_datum_t * p, const gnutls_datum_t * q, const gnutls_datum_t * u)

key: The structure to store the parsed key

m: holds the modulus

e: holds the public exponent

d: holds the private exponent

p: holds the first prime (p)

q: holds the second prime (q)

u: holds the coefficient

This function will convert the given RSA raw parameters to the native gnutls_x509_privkey_t format. The output will be stored in key .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_privkey_import_rsa_raw2

Function: int gnutls_x509_privkey_import_rsa_raw2 (gnutls_x509_privkey_t key, const gnutls_datum_t * m, const gnutls_datum_t * e, const gnutls_datum_t * d, const gnutls_datum_t * p, const gnutls_datum_t * q, const gnutls_datum_t * u, const gnutls_datum_t * e1, const gnutls_datum_t * e2)

key: The structure to store the parsed key

m: holds the modulus

e: holds the public exponent

d: holds the private exponent

p: holds the first prime (p)

q: holds the second prime (q)

u: holds the coefficient

e1: holds e1 = d mod (p-1)

e2: holds e2 = d mod (q-1)

This function will convert the given RSA raw parameters to the native gnutls_x509_privkey_t format. The output will be stored in key .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_privkey_init

Function: int gnutls_x509_privkey_init (gnutls_x509_privkey_t * key)

key: The structure to be initialized

This function will initialize an private key structure.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_privkey_sec_param

Function: gnutls_sec_param_t gnutls_x509_privkey_sec_param (gnutls_x509_privkey_t key)

key: a key structure

This function will return the security parameter appropriate with this private key.

Returns: On success, a valid security parameter is returned otherwise GNUTLS_SEC_PARAM_UNKNOWN is returned.

Since: 2.12.0

gnutls_x509_privkey_verify_params

Function: int gnutls_x509_privkey_verify_params (gnutls_x509_privkey_t key)

key: should contain a gnutls_x509_privkey_t structure

This function will verify the private key parameters.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_rdn_get

Function: int gnutls_x509_rdn_get (const gnutls_datum_t * idn, char * buf, size_t * sizeof_buf)

idn: should contain a DER encoded RDN sequence

buf: a pointer to a structure to hold the peer’s name

sizeof_buf: holds the size of buf

This function will return the name of the given RDN sequence. The name will be in the form "C=xxxx,O=yyyy,CN=zzzz" as described in RFC4514.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, or GNUTLS_E_SHORT_MEMORY_BUFFER is returned and * sizeof_buf is updated if the provided buffer is not long enough, otherwise a negative error value.

gnutls_x509_rdn_get_by_oid

Function: int gnutls_x509_rdn_get_by_oid (const gnutls_datum_t * idn, const char * oid, int indx, unsigned int raw_flag, void * buf, size_t * sizeof_buf)

idn: should contain a DER encoded RDN sequence

oid: an Object Identifier

indx: In case multiple same OIDs exist in the RDN indicates which to send. Use 0 for the first one.

raw_flag: If non (0) then the raw DER data are returned.

buf: a pointer to a structure to hold the peer’s name

sizeof_buf: holds the size of buf

This function will return the name of the given Object identifier, of the RDN sequence. The name will be encoded using the rules from RFC4514.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, or GNUTLS_E_SHORT_MEMORY_BUFFER is returned and * sizeof_buf is updated if the provided buffer is not long enough, otherwise a negative error value.

gnutls_x509_rdn_get_oid

Function: int gnutls_x509_rdn_get_oid (const gnutls_datum_t * idn, int indx, void * buf, size_t * sizeof_buf)

idn: should contain a DER encoded RDN sequence

indx: Indicates which OID to return. Use 0 for the first one.

buf: a pointer to a structure to hold the peer’s name OID

sizeof_buf: holds the size of buf

This function will return the specified Object identifier, of the RDN sequence.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, or GNUTLS_E_SHORT_MEMORY_BUFFER is returned and * sizeof_buf is updated if the provided buffer is not long enough, otherwise a negative error value.

Since: 2.4.0

gnutls_x509_trust_list_add_cas

Function: int gnutls_x509_trust_list_add_cas (gnutls_x509_trust_list_t list, const gnutls_x509_crt_t * clist, int clist_size, unsigned int flags)

list: The structure of the list

clist: A list of CAs

clist_size: The length of the CA list

flags: should be 0.

This function will add the given certificate authorities to the trusted list. The list of CAs must not be deinitialized during this structure’s lifetime.

Returns: The number of added elements is returned.

Since: 3.0

gnutls_x509_trust_list_add_crls

Function: int gnutls_x509_trust_list_add_crls (gnutls_x509_trust_list_t list, const gnutls_x509_crl_t * crl_list, int crl_size, unsigned int flags, unsigned int verification_flags)

list: The structure of the list

crl_list: A list of CRLs

crl_size: The length of the CRL list

flags: if GNUTLS_TL_VERIFY_CRL is given the CRLs will be verified before being added.

verification_flags: gnutls_certificate_verify_flags if flags specifies GNUTLS_TL_VERIFY_CRL

This function will add the given certificate revocation lists to the trusted list. The list of CRLs must not be deinitialized during this structure’s lifetime.

This function must be called after gnutls_x509_trust_list_add_cas() to allow verifying the CRLs for validity.

Returns: The number of added elements is returned.

Since: 3.0

gnutls_x509_trust_list_add_named_crt

Function: int gnutls_x509_trust_list_add_named_crt (gnutls_x509_trust_list_t list, gnutls_x509_crt_t cert, const void * name, size_t name_size, unsigned int flags)

list: The structure of the list

cert: A certificate

name: An identifier for the certificate

name_size: The size of the identifier

flags: should be 0.

This function will add the given certificate to the trusted list and associate it with a name. The certificate will not be be used for verification with gnutls_x509_trust_list_verify_crt() but only with gnutls_x509_trust_list_verify_named_crt() .

In principle this function can be used to set individual "server" certificates that are trusted by the user for that specific server but for no other purposes.

The certificate must not be deinitialized during the lifetime of the trusted list.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 3.0

gnutls_x509_trust_list_deinit

Function: void gnutls_x509_trust_list_deinit (gnutls_x509_trust_list_t list, unsigned int all)

list: The structure to be deinitialized

all: if non-(0) it will deinitialize all the certificates and CRLs contained in the structure.

This function will deinitialize a trust list.

Since: 3.0

gnutls_x509_trust_list_get_issuer

Function: int gnutls_x509_trust_list_get_issuer (gnutls_x509_trust_list_t list, gnutls_x509_crt_t cert, gnutls_x509_crt_t * issuer, unsigned int flags)

list: The structure of the list

cert: is the certificate to find issuer for

issuer: Will hold the issuer if any. Should be treated as constant.

flags: Use (0).

This function will attempt to find the issuer of the given certificate.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 3.0

gnutls_x509_trust_list_init

Function: int gnutls_x509_trust_list_init (gnutls_x509_trust_list_t * list, unsigned int size)

list: The structure to be initialized

size: The size of the internal hash table. Use (0) for default size.

This function will initialize an X.509 trust list structure.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 3.0

gnutls_x509_trust_list_verify_crt

Function: int gnutls_x509_trust_list_verify_crt (gnutls_x509_trust_list_t list, gnutls_x509_crt_t * cert_list, unsigned int cert_list_size, unsigned int flags, unsigned int * verify, gnutls_verify_output_function func)

list: The structure of the list

cert_list: is the certificate list to be verified

cert_list_size: is the certificate list size

flags: Flags that may be used to change the verification algorithm. Use OR of the gnutls_certificate_verify_flags enumerations.

verify: will hold the certificate verification output.

func: If non-null will be called on each chain element verification with the output.

This function will try to verify the given certificate and return its status.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 3.0

gnutls_x509_trust_list_verify_named_crt

Function: int gnutls_x509_trust_list_verify_named_crt (gnutls_x509_trust_list_t list, gnutls_x509_crt_t cert, const void * name, size_t name_size, unsigned int flags, unsigned int * verify, gnutls_verify_output_function func)

list: The structure of the list

cert: is the certificate to be verified

name: is the certificate’s name

name_size: is the certificate’s name size

flags: Flags that may be used to change the verification algorithm. Use OR of the gnutls_certificate_verify_flags enumerations.

verify: will hold the certificate verification output.

func: If non-null will be called on each chain element verification with the output.

This function will try to find a matching named certificate. If a match is found the certificate is considered valid. In addition to that this function will also check CRLs.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 3.0

OCSP API

The following functions are for OCSP certificate status checking. Their prototypes lie in gnutls/ocsp.h.

gnutls_ocsp_req_add_cert

Function: int gnutls_ocsp_req_add_cert (gnutls_ocsp_req_t req, gnutls_digest_algorithm_t digest, gnutls_x509_crt_t issuer, gnutls_x509_crt_t cert)

req: should contain a gnutls_ocsp_req_t structure

digest: hash algorithm, a gnutls_digest_algorithm_t value

issuer: issuer of subject certificate

cert: certificate to request status for

This function will add another request to the OCSP request for a particular certificate. The issuer name hash, issuer key hash, and serial number fields is populated as follows. The issuer name and the serial number is taken from cert . The issuer key is taken from issuer . The hashed values will be hashed using the digest algorithm, normally GNUTLS_DIG_SHA1 .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

gnutls_ocsp_req_add_cert_id

Function: int gnutls_ocsp_req_add_cert_id (gnutls_ocsp_req_t req, gnutls_digest_algorithm_t digest, const gnutls_datum_t * issuer_name_hash, const gnutls_datum_t * issuer_key_hash, const gnutls_datum_t * serial_number)

req: should contain a gnutls_ocsp_req_t structure

digest: hash algorithm, a gnutls_digest_algorithm_t value

issuer_name_hash: hash of issuer’s DN

issuer_key_hash: hash of issuer’s public key

serial_number: serial number of certificate to check

This function will add another request to the OCSP request for a particular certificate having the issuer name hash of issuer_name_hash and issuer key hash of issuer_key_hash (both hashed using digest ) and serial number serial_number .

The information needed corresponds to the CertID structure:

<informalexample><programlisting> CertID ::= SEQUENCE { hashAlgorithm AlgorithmIdentifier, issuerNameHash OCTET STRING, – Hash of Issuer’s DN issuerKeyHash OCTET STRING, – Hash of Issuers public key serialNumber CertificateSerialNumber } </programlisting></informalexample>

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

gnutls_ocsp_req_deinit

Function: void gnutls_ocsp_req_deinit (gnutls_ocsp_req_t req)

req: The structure to be deinitialized

This function will deinitialize a OCSP request structure.

gnutls_ocsp_req_export

Function: int gnutls_ocsp_req_export (gnutls_ocsp_req_t req, gnutls_datum_t * data)

req: Holds the OCSP request

data: newly allocate buffer holding DER encoded OCSP request

This function will export the OCSP request to DER format.

Returns: In case of failure a negative error code will be returned, and 0 on success.

gnutls_ocsp_req_get_cert_id

Function: int gnutls_ocsp_req_get_cert_id (gnutls_ocsp_req_t req, unsigned indx, gnutls_digest_algorithm_t * digest, gnutls_datum_t * issuer_name_hash, gnutls_datum_t * issuer_key_hash, gnutls_datum_t * serial_number)

req: should contain a gnutls_ocsp_req_t structure

indx: Specifies which extension OID to get. Use (0) to get the first one.

digest: output variable with gnutls_digest_algorithm_t hash algorithm

issuer_name_hash: output buffer with hash of issuer’s DN

issuer_key_hash: output buffer with hash of issuer’s public key

serial_number: output buffer with serial number of certificate to check

This function will return the certificate information of the indx ’ed request in the OCSP request. The information returned corresponds to the CertID structure:

<informalexample><programlisting> CertID ::= SEQUENCE { hashAlgorithm AlgorithmIdentifier, issuerNameHash OCTET STRING, – Hash of Issuer’s DN issuerKeyHash OCTET STRING, – Hash of Issuers public key serialNumber CertificateSerialNumber } </programlisting></informalexample>

Each of the pointers to output variables may be NULL to indicate that the caller is not interested in that value.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned. If you have reached the last CertID available GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.

gnutls_ocsp_req_get_extension

Function: int gnutls_ocsp_req_get_extension (gnutls_ocsp_req_t req, unsigned indx, gnutls_datum_t * oid, unsigned int * critical, gnutls_datum_t * data)

req: should contain a gnutls_ocsp_req_t structure

indx: Specifies which extension OID to get. Use (0) to get the first one.

oid: will hold newly allocated buffer with OID of extension, may be NULL

critical: output variable with critical flag, may be NULL.

data: will hold newly allocated buffer with extension data, may be NULL

This function will return all information about the requested extension in the OCSP request. The information returned is the OID, the critical flag, and the data itself. The extension OID will be stored as a string. Any of oid , critical , and data may be NULL which means that the caller is not interested in getting that information back.

The caller needs to deallocate memory by calling gnutls_free() on oid ->data and data ->data.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned. If you have reached the last extension available GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.

gnutls_ocsp_req_get_nonce

Function: int gnutls_ocsp_req_get_nonce (gnutls_ocsp_req_t req, unsigned int * critical, gnutls_datum_t * nonce)

req: should contain a gnutls_ocsp_req_t structure

critical: whether nonce extension is marked critical, or NULL

nonce: will hold newly allocated buffer with nonce data

This function will return the OCSP request nonce extension data.

The caller needs to deallocate memory by calling gnutls_free() on nonce ->data.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

gnutls_ocsp_req_get_version

Function: int gnutls_ocsp_req_get_version (gnutls_ocsp_req_t req)

req: should contain a gnutls_ocsp_req_t structure

This function will return the version of the OCSP request. Typically this is always 1 indicating version 1.

Returns: version of OCSP request, or a negative error code on error.

gnutls_ocsp_req_import

Function: int gnutls_ocsp_req_import (gnutls_ocsp_req_t req, const gnutls_datum_t * data)

req: The structure to store the parsed request.

data: DER encoded OCSP request.

This function will convert the given DER encoded OCSP request to the native gnutls_ocsp_req_t format. The output will be stored in req .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_ocsp_req_init

Function: int gnutls_ocsp_req_init (gnutls_ocsp_req_t * req)

req: The structure to be initialized

This function will initialize an OCSP request structure.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_ocsp_req_print

Function: int gnutls_ocsp_req_print (gnutls_ocsp_req_t req, gnutls_ocsp_print_formats_t format, gnutls_datum_t * out)

req: The structure to be printed

format: Indicate the format to use

out: Newly allocated datum with (0) terminated string.

This function will pretty print a OCSP request, suitable for display to a human.

If the format is GNUTLS_PRINT_FULL then all fields of the request will be output, on multiple lines.

The output out ->data needs to be deallocate using gnutls_free() .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_ocsp_req_randomize_nonce

Function: int gnutls_ocsp_req_randomize_nonce (gnutls_ocsp_req_t req)

req: should contain a gnutls_ocsp_req_t structure

This function will add or update an nonce extension to the OCSP request with a newly generated random value.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

gnutls_ocsp_req_set_extension

Function: int gnutls_ocsp_req_set_extension (gnutls_ocsp_req_t req, const char * oid, unsigned int critical, const gnutls_datum_t * data)

req: should contain a gnutls_ocsp_req_t structure

oid: buffer with OID of extension as a string.

critical: critical flag, normally false.

data: the extension data

This function will add an extension to the OCSP request. Calling this function multiple times for the same OID will overwrite values from earlier calls.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

gnutls_ocsp_req_set_nonce

Function: int gnutls_ocsp_req_set_nonce (gnutls_ocsp_req_t req, unsigned int critical, const gnutls_datum_t * nonce)

req: should contain a gnutls_ocsp_req_t structure

critical: critical flag, normally false.

nonce: the nonce data

This function will add an nonce extension to the OCSP request. Calling this function multiple times will overwrite values from earlier calls.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

gnutls_ocsp_resp_deinit

Function: void gnutls_ocsp_resp_deinit (gnutls_ocsp_resp_t resp)

resp: The structure to be deinitialized

This function will deinitialize a OCSP response structure.

gnutls_ocsp_resp_export

Function: int gnutls_ocsp_resp_export (gnutls_ocsp_resp_t resp, gnutls_datum_t * data)

resp: Holds the OCSP response

data: newly allocate buffer holding DER encoded OCSP response

This function will export the OCSP response to DER format.

Returns: In case of failure a negative error code will be returned, and 0 on success.

gnutls_ocsp_resp_get_certs

Function: int gnutls_ocsp_resp_get_certs (gnutls_ocsp_resp_t resp, gnutls_x509_crt_t ** certs, size_t * ncerts)

resp: should contain a gnutls_ocsp_resp_t structure

certs: newly allocated array with gnutls_x509_crt_t certificates

ncerts: output variable with number of allocated certs.

This function will extract the X.509 certificates found in the Basic OCSP Response. The certs output variable will hold a newly allocated zero-terminated array with X.509 certificates.

Every certificate in the array needs to be de-allocated with gnutls_x509_crt_deinit() and the array itself must be freed using gnutls_free() .

Both the certs and ncerts variables may be NULL. Then the function will work as normal but will not return the NULL:d information. This can be used to get the number of certificates only, or to just get the certificate array without its size.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_ocsp_resp_get_extension

Function: int gnutls_ocsp_resp_get_extension (gnutls_ocsp_resp_t resp, unsigned indx, gnutls_datum_t * oid, unsigned int * critical, gnutls_datum_t * data)

resp: should contain a gnutls_ocsp_resp_t structure

indx: Specifies which extension OID to get. Use (0) to get the first one.

oid: will hold newly allocated buffer with OID of extension, may be NULL

critical: output variable with critical flag, may be NULL.

data: will hold newly allocated buffer with extension data, may be NULL

This function will return all information about the requested extension in the OCSP response. The information returned is the OID, the critical flag, and the data itself. The extension OID will be stored as a string. Any of oid , critical , and data may be NULL which means that the caller is not interested in getting that information back.

The caller needs to deallocate memory by calling gnutls_free() on oid ->data and data ->data.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned. If you have reached the last extension available GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.

gnutls_ocsp_resp_get_nonce

Function: int gnutls_ocsp_resp_get_nonce (gnutls_ocsp_resp_t resp, unsigned int * critical, gnutls_datum_t * nonce)

resp: should contain a gnutls_ocsp_resp_t structure

critical: whether nonce extension is marked critical

nonce: will hold newly allocated buffer with nonce data

This function will return the Basic OCSP Response nonce extension data.

The caller needs to deallocate memory by calling gnutls_free() on nonce ->data.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

gnutls_ocsp_resp_get_produced

Function: time_t gnutls_ocsp_resp_get_produced (gnutls_ocsp_resp_t resp)

resp: should contain a gnutls_ocsp_resp_t structure

This function will return the time when the OCSP response was signed.

Returns: signing time, or (time_t)-1 on error.

gnutls_ocsp_resp_get_responder

Function: int gnutls_ocsp_resp_get_responder (gnutls_ocsp_resp_t resp, gnutls_datum_t * dn)

resp: should contain a gnutls_ocsp_resp_t structure

dn: newly allocated buffer with name

This function will extract the name of the Basic OCSP Response in the provided buffer. The name will be in the form "C=xxxx,O=yyyy,CN=zzzz" as described in RFC2253. The output string will be ASCII or UTF-8 encoded, depending on the certificate data.

The caller needs to deallocate memory by calling gnutls_free() on dn ->data.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

gnutls_ocsp_resp_get_response

Function: int gnutls_ocsp_resp_get_response (gnutls_ocsp_resp_t resp, gnutls_datum_t * response_type_oid, gnutls_datum_t * response)

resp: should contain a gnutls_ocsp_resp_t structure

response_type_oid: newly allocated output buffer with response type OID

response: newly allocated output buffer with DER encoded response

This function will extract the response type OID in and the response data from an OCSP response. Normally the response_type_oid is always "1.3.6.1.5.5.7.48.1.1" which means the response should be decoded as a Basic OCSP Response, but technically other response types could be used.

This function is typically only useful when you want to extract the response type OID of an response for diagnostic purposes. Otherwise gnutls_ocsp_resp_import() will decode the basic OCSP response part and the caller need not worry about that aspect.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_ocsp_resp_get_signature

Function: int gnutls_ocsp_resp_get_signature (gnutls_ocsp_resp_t resp, gnutls_datum_t * sig)

resp: should contain a gnutls_ocsp_resp_t structure

sig: newly allocated output buffer with signature data

This function will extract the signature field of a OCSP response.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_ocsp_resp_get_signature_algorithm

Function: int gnutls_ocsp_resp_get_signature_algorithm (gnutls_ocsp_resp_t resp)

resp: should contain a gnutls_ocsp_resp_t structure

This function will return a value of the gnutls_sign_algorithm_t enumeration that is the signature algorithm that has been used to sign the OCSP response.

Returns: a gnutls_sign_algorithm_t value, or a negative error code on error.

gnutls_ocsp_resp_get_single

Function: int gnutls_ocsp_resp_get_single (gnutls_ocsp_resp_t resp, unsigned indx, gnutls_digest_algorithm_t * digest, gnutls_datum_t * issuer_name_hash, gnutls_datum_t * issuer_key_hash, gnutls_datum_t * serial_number, unsigned int * cert_status, time_t * this_update, time_t * next_update, time_t * revocation_time, unsigned int * revocation_reason)

resp: should contain a gnutls_ocsp_resp_t structure

indx: Specifies which extension OID to get. Use (0) to get the first one.

digest: output variable with gnutls_digest_algorithm_t hash algorithm

issuer_name_hash: output buffer with hash of issuer’s DN

issuer_key_hash: output buffer with hash of issuer’s public key

serial_number: output buffer with serial number of certificate to check

cert_status: a certificate status, a gnutls_ocsp_cert_status_t enum.

this_update: time at which the status is known to be correct.

next_update: when newer information will be available, or (time_t)-1 if unspecified

revocation_time: when cert_status is GNUTLS_OCSP_CERT_REVOKED , holds time of revocation.

revocation_reason: revocation reason, a gnutls_x509_crl_reason_t enum.

This function will return the certificate information of the indx ’ed response in the Basic OCSP Response resp . The information returned corresponds to the SingleResponse structure except the final singleExtensions, reproduced here for illustration:

<informalexample><programlisting> SingleResponse ::= SEQUENCE { certID CertID, certStatus CertStatus, thisUpdate GeneralizedTime, nextUpdate [0] EXPLICIT GeneralizedTime OPTIONAL, singleExtensions [1] EXPLICIT Extensions OPTIONAL }

CertID ::= SEQUENCE { hashAlgorithm AlgorithmIdentifier, issuerNameHash OCTET STRING, – Hash of Issuer’s DN issuerKeyHash OCTET STRING, – Hash of Issuers public key serialNumber CertificateSerialNumber }

CertStatus ::= CHOICE { good [0] IMPLICIT NULL, revoked [1] IMPLICIT RevokedInfo, unknown [2] IMPLICIT UnknownInfo }

RevokedInfo ::= SEQUENCE { revocationTime GeneralizedTime, revocationReason [0] EXPLICIT CRLReason OPTIONAL } </programlisting></informalexample>

Each of the pointers to output variables may be NULL to indicate that the caller is not interested in that value.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned. If you have reached the last CertID available GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.

gnutls_ocsp_resp_get_status

Function: int gnutls_ocsp_resp_get_status (gnutls_ocsp_resp_t resp)

resp: should contain a gnutls_ocsp_resp_t structure

This function will return the status of a OCSP response, an gnutls_ocsp_resp_status_t enumeration.

Returns: status of OCSP request as a gnutls_ocsp_resp_status_t , or a negative error code on error.

gnutls_ocsp_resp_get_version

Function: int gnutls_ocsp_resp_get_version (gnutls_ocsp_resp_t resp)

resp: should contain a gnutls_ocsp_resp_t structure

This function will return the version of the Basic OCSP Response. Typically this is always 1 indicating version 1.

Returns: version of Basic OCSP response, or a negative error code on error.

gnutls_ocsp_resp_import

Function: int gnutls_ocsp_resp_import (gnutls_ocsp_resp_t resp, const gnutls_datum_t * data)

resp: The structure to store the parsed response.

data: DER encoded OCSP response.

This function will convert the given DER encoded OCSP response to the native gnutls_ocsp_resp_t format. It also decodes the Basic OCSP Response part, if any. The output will be stored in resp .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_ocsp_resp_init

Function: int gnutls_ocsp_resp_init (gnutls_ocsp_resp_t * resp)

resp: The structure to be initialized

This function will initialize an OCSP response structure.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_ocsp_resp_print

Function: int gnutls_ocsp_resp_print (gnutls_ocsp_resp_t resp, gnutls_ocsp_print_formats_t format, gnutls_datum_t * out)

resp: The structure to be printed

format: Indicate the format to use

out: Newly allocated datum with (0) terminated string.

This function will pretty print a OCSP response, suitable for display to a human.

If the format is GNUTLS_PRINT_FULL then all fields of the response will be output, on multiple lines.

The output out ->data needs to be deallocate using gnutls_free() .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_ocsp_resp_verify

Function: int gnutls_ocsp_resp_verify (gnutls_ocsp_resp_t resp, gnutls_x509_trust_list_t trustlist, unsigned int * verify, unsigned int flags)

resp: should contain a gnutls_ocsp_resp_t structure

trustlist: trust anchors as a gnutls_x509_trust_list_t structure

verify: output variable with verification status, an gnutls_ocsp_cert_status_t

flags: verification flags, 0 for now.

Verify signature of the Basic OCSP Response against the public key in the certificate of a trusted signer. The trustlist should be populated with trust anchors. The function will extract the signer certificate from the Basic OCSP Response and will verify it against the trustlist . A trusted signer is a certificate that is either in trustlist , or it is signed directly by a certificate in trustlist and has the id-ad-ocspSigning Extended Key Usage bit set.

The output verify variable will hold verification status codes (e.g., GNUTLS_OCSP_VERIFY_SIGNER_NOT_FOUND , GNUTLS_OCSP_VERIFY_INSECURE_ALGORITHM ) which are only valid if the function returned GNUTLS_E_SUCCESS .

Note that the function returns GNUTLS_E_SUCCESS even when verification failed. The caller must always inspect the verify variable to find out the verification status.

The flags variable should be 0 for now.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_ocsp_resp_verify_direct

Function: int gnutls_ocsp_resp_verify_direct (gnutls_ocsp_resp_t resp, gnutls_x509_crt_t issuer, unsigned int * verify, unsigned int flags)

resp: should contain a gnutls_ocsp_resp_t structure

issuer: certificate believed to have signed the response

verify: output variable with verification status, an gnutls_ocsp_cert_status_t

flags: verification flags, 0 for now.

Verify signature of the Basic OCSP Response against the public key in the issuer certificate.

The output verify variable will hold verification status codes (e.g., GNUTLS_OCSP_VERIFY_SIGNER_NOT_FOUND , GNUTLS_OCSP_VERIFY_INSECURE_ALGORITHM ) which are only valid if the function returned GNUTLS_E_SUCCESS .

Note that the function returns GNUTLS_E_SUCCESS even when verification failed. The caller must always inspect the verify variable to find out the verification status.

The flags variable should be 0 for now.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

OpenPGP API

The following functions are to be used for OpenPGP certificate handling. Their prototypes lie in gnutls/openpgp.h.

gnutls_certificate_set_openpgp_key

Function: int gnutls_certificate_set_openpgp_key (gnutls_certificate_credentials_t res, gnutls_openpgp_crt_t crt, gnutls_openpgp_privkey_t pkey)

res: is a gnutls_certificate_credentials_t structure.

crt: contains an openpgp public key

pkey: is an openpgp private key

This function sets a certificate/private key pair in the gnutls_certificate_credentials_t structure. This function may be called more than once (in case multiple keys/certificates exist for the server).

Note that this function requires that the preferred key ids have been set and be used. See gnutls_openpgp_crt_set_preferred_key_id() . Otherwise the master key will be used.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

gnutls_certificate_set_openpgp_key_file

Function: int gnutls_certificate_set_openpgp_key_file (gnutls_certificate_credentials_t res, const char * certfile, const char * keyfile, gnutls_openpgp_crt_fmt_t format)

res: the destination context to save the data.

certfile: the file that contains the public key.

keyfile: the file that contains the secret key.

format: the format of the keys

This funtion is used to load OpenPGP keys into the GnuTLS credentials structure. The file should contain at least one valid non encrypted subkey.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_certificate_set_openpgp_key_file2

Function: int gnutls_certificate_set_openpgp_key_file2 (gnutls_certificate_credentials_t                                           res, const char * certfile, const char * keyfile, const char * subkey_id, gnutls_openpgp_crt_fmt_t format)

res: the destination context to save the data.

certfile: the file that contains the public key.

keyfile: the file that contains the secret key.

subkey_id: a hex encoded subkey id

format: the format of the keys

This funtion is used to load OpenPGP keys into the GnuTLS credential structure. The file should contain at least one valid non encrypted subkey.

The special keyword "auto" is also accepted as subkey_id . In that case the gnutls_openpgp_crt_get_auth_subkey() will be used to retrieve the subkey.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.4.0

gnutls_certificate_set_openpgp_key_mem

Function: int gnutls_certificate_set_openpgp_key_mem (gnutls_certificate_credentials_t res, const gnutls_datum_t * cert, const gnutls_datum_t * key, gnutls_openpgp_crt_fmt_t format)

res: the destination context to save the data.

cert: the datum that contains the public key.

key: the datum that contains the secret key.

format: the format of the keys

This funtion is used to load OpenPGP keys into the GnuTLS credential structure. The datum should contain at least one valid non encrypted subkey.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_certificate_set_openpgp_key_mem2

Function: int gnutls_certificate_set_openpgp_key_mem2 (gnutls_certificate_credentials_t res, const gnutls_datum_t * cert, const gnutls_datum_t * key, const char * subkey_id, gnutls_openpgp_crt_fmt_t format)

res: the destination context to save the data.

cert: the datum that contains the public key.

key: the datum that contains the secret key.

subkey_id: a hex encoded subkey id

format: the format of the keys

This funtion is used to load OpenPGP keys into the GnuTLS credentials structure. The datum should contain at least one valid non encrypted subkey.

The special keyword "auto" is also accepted as subkey_id . In that case the gnutls_openpgp_crt_get_auth_subkey() will be used to retrieve the subkey.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.4.0

gnutls_certificate_set_openpgp_keyring_file

Function: int gnutls_certificate_set_openpgp_keyring_file (gnutls_certificate_credentials_t c, const char * file, gnutls_openpgp_crt_fmt_t format)

c: A certificate credentials structure

file: filename of the keyring.

format: format of keyring.

The function is used to set keyrings that will be used internally by various OpenPGP functions. For example to find a key when it is needed for an operations. The keyring will also be used at the verification functions.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_certificate_set_openpgp_keyring_mem

Function: int gnutls_certificate_set_openpgp_keyring_mem (gnutls_certificate_credentials_t                                             c, const uint8_t * data, size_t dlen, gnutls_openpgp_crt_fmt_t format)

c: A certificate credentials structure

data: buffer with keyring data.

dlen: length of data buffer.

format: the format of the keyring

The function is used to set keyrings that will be used internally by various OpenPGP functions. For example to find a key when it is needed for an operations. The keyring will also be used at the verification functions.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_openpgp_crt_check_hostname

Function: int gnutls_openpgp_crt_check_hostname (gnutls_openpgp_crt_t key, const char * hostname)

key: should contain a gnutls_openpgp_crt_t structure

hostname: A null terminated string that contains a DNS name

This function will check if the given key’s owner matches the given hostname. This is a basic implementation of the matching described in RFC2818 (HTTPS), which takes into account wildcards.

Returns: GNUTLS_E_SUCCESS on success, or an error code.

gnutls_openpgp_crt_deinit

Function: void gnutls_openpgp_crt_deinit (gnutls_openpgp_crt_t key)

key: The structure to be initialized

This function will deinitialize a key structure.

gnutls_openpgp_crt_export

Function: int gnutls_openpgp_crt_export (gnutls_openpgp_crt_t key, gnutls_openpgp_crt_fmt_t format, void * output_data, size_t * output_data_size)

key: Holds the key.

format: One of gnutls_openpgp_crt_fmt_t elements.

output_data: will contain the key base64 encoded or raw

output_data_size: holds the size of output_data (and will be replaced by the actual size of parameters)

This function will convert the given key to RAW or Base64 format. If the buffer provided is not long enough to hold the output, then GNUTLS_E_SHORT_MEMORY_BUFFER will be returned.

Returns: GNUTLS_E_SUCCESS on success, or an error code.

gnutls_openpgp_crt_get_auth_subkey

Function: int gnutls_openpgp_crt_get_auth_subkey (gnutls_openpgp_crt_t crt, gnutls_openpgp_keyid_t keyid, unsigned int flag)

crt: the structure that contains the OpenPGP public key.

keyid: the struct to save the keyid.

flag: Non (0) indicates that a valid subkey is always returned.

Returns the 64-bit keyID of the first valid OpenPGP subkey marked for authentication. If flag is non (0) and no authentication subkey exists, then a valid subkey will be returned even if it is not marked for authentication. Returns the 64-bit keyID of the first valid OpenPGP subkey marked for authentication. If flag is non (0) and no authentication subkey exists, then a valid subkey will be returned even if it is not marked for authentication.

Returns: GNUTLS_E_SUCCESS on success, or an error code.

gnutls_openpgp_crt_get_creation_time

Function: time_t gnutls_openpgp_crt_get_creation_time (gnutls_openpgp_crt_t key)

key: the structure that contains the OpenPGP public key.

Get key creation time.

Returns: the timestamp when the OpenPGP key was created.

gnutls_openpgp_crt_get_expiration_time

Function: time_t gnutls_openpgp_crt_get_expiration_time (gnutls_openpgp_crt_t key)

key: the structure that contains the OpenPGP public key.

Get key expiration time. A value of ’0’ means that the key doesn’t expire at all.

Returns: the time when the OpenPGP key expires.

gnutls_openpgp_crt_get_fingerprint

Function: int gnutls_openpgp_crt_get_fingerprint (gnutls_openpgp_crt_t key, void * fpr, size_t * fprlen)

key: the raw data that contains the OpenPGP public key.

fpr: the buffer to save the fingerprint, must hold at least 20 bytes.

fprlen: the integer to save the length of the fingerprint.

Get key fingerprint. Depending on the algorithm, the fingerprint can be 16 or 20 bytes.

Returns: On success, 0 is returned. Otherwise, an error code.

gnutls_openpgp_crt_get_key_id

Function: int gnutls_openpgp_crt_get_key_id (gnutls_openpgp_crt_t key, gnutls_openpgp_keyid_t keyid)

key: the structure that contains the OpenPGP public key.

keyid: the buffer to save the keyid.

Get key id string.

Returns: the 64-bit keyID of the OpenPGP key.

Since: 2.4.0

gnutls_openpgp_crt_get_key_usage

Function: int gnutls_openpgp_crt_get_key_usage (gnutls_openpgp_crt_t key, unsigned int * key_usage)

key: should contain a gnutls_openpgp_crt_t structure

key_usage: where the key usage bits will be stored

This function will return certificate’s key usage, by checking the key algorithm. The key usage value will ORed values of the: GNUTLS_KEY_DIGITAL_SIGNATURE , GNUTLS_KEY_KEY_ENCIPHERMENT .

Returns: GNUTLS_E_SUCCESS on success, or an error code.

gnutls_openpgp_crt_get_name

Function: int gnutls_openpgp_crt_get_name (gnutls_openpgp_crt_t key, int idx, char * buf, size_t * sizeof_buf)

key: the structure that contains the OpenPGP public key.

idx: the index of the ID to extract

buf: a pointer to a structure to hold the name, may be NULL to only get the sizeof_buf .

sizeof_buf: holds the maximum size of buf , on return hold the actual/required size of buf .

Extracts the userID from the parsed OpenPGP key.

Returns: GNUTLS_E_SUCCESS on success, and if the index of the ID does not exist GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE , or an error code.

gnutls_openpgp_crt_get_pk_algorithm

Function: gnutls_pk_algorithm_t gnutls_openpgp_crt_get_pk_algorithm (gnutls_openpgp_crt_t key, unsigned int * bits)

key: is an OpenPGP key

bits: if bits is non null it will hold the size of the parameters’ in bits

This function will return the public key algorithm of an OpenPGP certificate.

If bits is non null, it should have enough size to hold the parameters size in bits. For RSA the bits returned is the modulus. For DSA the bits returned are of the public exponent.

Returns: a member of the gnutls_pk_algorithm_t enumeration on success, or GNUTLS_PK_UNKNOWN on error.

gnutls_openpgp_crt_get_pk_dsa_raw

Function: int gnutls_openpgp_crt_get_pk_dsa_raw (gnutls_openpgp_crt_t crt, gnutls_datum_t * p, gnutls_datum_t * q, gnutls_datum_t * g, gnutls_datum_t * y)

crt: Holds the certificate

p: will hold the p

q: will hold the q

g: will hold the g

y: will hold the y

This function will export the DSA public key’s parameters found in the given certificate. The new parameters will be allocated using gnutls_malloc() and will be stored in the appropriate datum.

Returns: GNUTLS_E_SUCCESS on success, otherwise a negative error code.

Since: 2.4.0

gnutls_openpgp_crt_get_pk_rsa_raw

Function: int gnutls_openpgp_crt_get_pk_rsa_raw (gnutls_openpgp_crt_t crt, gnutls_datum_t * m, gnutls_datum_t * e)

crt: Holds the certificate

m: will hold the modulus

e: will hold the public exponent

This function will export the RSA public key’s parameters found in the given structure. The new parameters will be allocated using gnutls_malloc() and will be stored in the appropriate datum.

Returns: GNUTLS_E_SUCCESS on success, otherwise a negative error code.

Since: 2.4.0

gnutls_openpgp_crt_get_preferred_key_id

Function: int gnutls_openpgp_crt_get_preferred_key_id (gnutls_openpgp_crt_t key, gnutls_openpgp_keyid_t keyid)

key: the structure that contains the OpenPGP public key.

keyid: the struct to save the keyid.

Get preferred key id. If it hasn’t been set it returns GNUTLS_E_INVALID_REQUEST .

Returns: the 64-bit preferred keyID of the OpenPGP key.

gnutls_openpgp_crt_get_revoked_status

Function: int gnutls_openpgp_crt_get_revoked_status (gnutls_openpgp_crt_t key)

key: the structure that contains the OpenPGP public key.

Get revocation status of key.

Returns: true (1) if the key has been revoked, or false (0) if it has not.

Since: 2.4.0

gnutls_openpgp_crt_get_subkey_count

Function: int gnutls_openpgp_crt_get_subkey_count (gnutls_openpgp_crt_t key)

key: is an OpenPGP key

This function will return the number of subkeys present in the given OpenPGP certificate.

Returns: the number of subkeys, or a negative error code on error.

Since: 2.4.0

gnutls_openpgp_crt_get_subkey_creation_time

Function: time_t gnutls_openpgp_crt_get_subkey_creation_time (gnutls_openpgp_crt_t key, unsigned int idx)

key: the structure that contains the OpenPGP public key.

idx: the subkey index

Get subkey creation time.

Returns: the timestamp when the OpenPGP sub-key was created.

Since: 2.4.0

gnutls_openpgp_crt_get_subkey_expiration_time

Function: time_t gnutls_openpgp_crt_get_subkey_expiration_time (gnutls_openpgp_crt_t key, unsigned int idx)

key: the structure that contains the OpenPGP public key.

idx: the subkey index

Get subkey expiration time. A value of ’0’ means that the key doesn’t expire at all.

Returns: the time when the OpenPGP key expires.

Since: 2.4.0

gnutls_openpgp_crt_get_subkey_fingerprint

Function: int gnutls_openpgp_crt_get_subkey_fingerprint (gnutls_openpgp_crt_t key, unsigned int idx, void * fpr, size_t * fprlen)

key: the raw data that contains the OpenPGP public key.

idx: the subkey index

fpr: the buffer to save the fingerprint, must hold at least 20 bytes.

fprlen: the integer to save the length of the fingerprint.

Get key fingerprint of a subkey. Depending on the algorithm, the fingerprint can be 16 or 20 bytes.

Returns: On success, 0 is returned. Otherwise, an error code.

Since: 2.4.0

gnutls_openpgp_crt_get_subkey_id

Function: int gnutls_openpgp_crt_get_subkey_id (gnutls_openpgp_crt_t key, unsigned int idx, gnutls_openpgp_keyid_t keyid)

key: the structure that contains the OpenPGP public key.

idx: the subkey index

keyid: the buffer to save the keyid.

Get the subkey’s key-id.

Returns: the 64-bit keyID of the OpenPGP key.

gnutls_openpgp_crt_get_subkey_idx

Function: int gnutls_openpgp_crt_get_subkey_idx (gnutls_openpgp_crt_t key, const gnutls_openpgp_keyid_t keyid)

key: the structure that contains the OpenPGP public key.

keyid: the keyid.

Get subkey’s index.

Returns: the index of the subkey or a negative error value.

Since: 2.4.0

gnutls_openpgp_crt_get_subkey_pk_algorithm

Function: gnutls_pk_algorithm_t gnutls_openpgp_crt_get_subkey_pk_algorithm (gnutls_openpgp_crt_t key, unsigned int idx, unsigned int * bits)

key: is an OpenPGP key

idx: is the subkey index

bits: if bits is non null it will hold the size of the parameters’ in bits

This function will return the public key algorithm of a subkey of an OpenPGP certificate.

If bits is non null, it should have enough size to hold the parameters size in bits. For RSA the bits returned is the modulus. For DSA the bits returned are of the public exponent.

Returns: a member of the gnutls_pk_algorithm_t enumeration on success, or GNUTLS_PK_UNKNOWN on error.

Since: 2.4.0

gnutls_openpgp_crt_get_subkey_pk_dsa_raw

Function: int gnutls_openpgp_crt_get_subkey_pk_dsa_raw (gnutls_openpgp_crt_t crt, unsigned int idx, gnutls_datum_t * p, gnutls_datum_t * q, gnutls_datum_t * g, gnutls_datum_t * y)

crt: Holds the certificate

idx: Is the subkey index

p: will hold the p

q: will hold the q

g: will hold the g

y: will hold the y

This function will export the DSA public key’s parameters found in the given certificate. The new parameters will be allocated using gnutls_malloc() and will be stored in the appropriate datum.

Returns: GNUTLS_E_SUCCESS on success, otherwise a negative error code.

Since: 2.4.0

gnutls_openpgp_crt_get_subkey_pk_rsa_raw

Function: int gnutls_openpgp_crt_get_subkey_pk_rsa_raw (gnutls_openpgp_crt_t crt, unsigned int idx, gnutls_datum_t * m, gnutls_datum_t * e)

crt: Holds the certificate

idx: Is the subkey index

m: will hold the modulus

e: will hold the public exponent

This function will export the RSA public key’s parameters found in the given structure. The new parameters will be allocated using gnutls_malloc() and will be stored in the appropriate datum.

Returns: GNUTLS_E_SUCCESS on success, otherwise a negative error code.

Since: 2.4.0

gnutls_openpgp_crt_get_subkey_revoked_status

Function: int gnutls_openpgp_crt_get_subkey_revoked_status (gnutls_openpgp_crt_t key, unsigned int idx)

key: the structure that contains the OpenPGP public key.

idx: is the subkey index

Get subkey revocation status. A negative error code indicates an error.

Returns: true (1) if the key has been revoked, or false (0) if it has not.

Since: 2.4.0

gnutls_openpgp_crt_get_subkey_usage

Function: int gnutls_openpgp_crt_get_subkey_usage (gnutls_openpgp_crt_t key, unsigned int idx, unsigned int * key_usage)

key: should contain a gnutls_openpgp_crt_t structure

idx: the subkey index

key_usage: where the key usage bits will be stored

This function will return certificate’s key usage, by checking the key algorithm. The key usage value will ORed values of GNUTLS_KEY_DIGITAL_SIGNATURE or GNUTLS_KEY_KEY_ENCIPHERMENT .

A negative error code may be returned in case of parsing error.

Returns: key usage value.

Since: 2.4.0

gnutls_openpgp_crt_get_version

Function: int gnutls_openpgp_crt_get_version (gnutls_openpgp_crt_t key)

key: the structure that contains the OpenPGP public key.

Extract the version of the OpenPGP key.

Returns: the version number is returned, or a negative error code on errors.

gnutls_openpgp_crt_import

Function: int gnutls_openpgp_crt_import (gnutls_openpgp_crt_t key, const gnutls_datum_t * data, gnutls_openpgp_crt_fmt_t format)

key: The structure to store the parsed key.

data: The RAW or BASE64 encoded key.

format: One of gnutls_openpgp_crt_fmt_t elements.

This function will convert the given RAW or Base64 encoded key to the native gnutls_openpgp_crt_t format. The output will be stored in ’key’.

Returns: GNUTLS_E_SUCCESS on success, or an error code.

gnutls_openpgp_crt_init

Function: int gnutls_openpgp_crt_init (gnutls_openpgp_crt_t * key)

key: The structure to be initialized

This function will initialize an OpenPGP key structure.

Returns: GNUTLS_E_SUCCESS on success, or an error code.

gnutls_openpgp_crt_print

Function: int gnutls_openpgp_crt_print (gnutls_openpgp_crt_t cert, gnutls_certificate_print_formats_t format, gnutls_datum_t * out)

cert: The structure to be printed

format: Indicate the format to use

out: Newly allocated datum with (0) terminated string.

This function will pretty print an OpenPGP certificate, suitable for display to a human.

The format should be (0) for future compatibility.

The output out needs to be deallocate using gnutls_free() .

Returns: GNUTLS_E_SUCCESS on success, or an error code.

gnutls_openpgp_crt_set_preferred_key_id

Function: int gnutls_openpgp_crt_set_preferred_key_id (gnutls_openpgp_crt_t key, const gnutls_openpgp_keyid_t keyid)

key: the structure that contains the OpenPGP public key.

keyid: the selected keyid

This allows setting a preferred key id for the given certificate. This key will be used by functions that involve key handling.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

gnutls_openpgp_crt_verify_ring

Function: int gnutls_openpgp_crt_verify_ring (gnutls_openpgp_crt_t key, gnutls_openpgp_keyring_t keyring, unsigned int flags, unsigned int * verify)

key: the structure that holds the key.

keyring: holds the keyring to check against

flags: unused (should be 0)

verify: will hold the certificate verification output.

Verify all signatures in the key, using the given set of keys (keyring).

The key verification output will be put in verify and will be one or more of the gnutls_certificate_status_t enumerated elements bitwise or’d.

Returns: GNUTLS_E_SUCCESS on success, or an error code.

gnutls_openpgp_crt_verify_self

Function: int gnutls_openpgp_crt_verify_self (gnutls_openpgp_crt_t key, unsigned int flags, unsigned int * verify)

key: the structure that holds the key.

flags: unused (should be 0)

verify: will hold the key verification output.

Verifies the self signature in the key. The key verification output will be put in verify and will be one or more of the gnutls_certificate_status_t enumerated elements bitwise or’d.

Returns: GNUTLS_E_SUCCESS on success, or an error code.

gnutls_openpgp_keyring_check_id

Function: int gnutls_openpgp_keyring_check_id (gnutls_openpgp_keyring_t ring, const gnutls_openpgp_keyid_t keyid, unsigned int flags)

ring: holds the keyring to check against

keyid: will hold the keyid to check for.

flags: unused (should be 0)

Check if a given key ID exists in the keyring.

Returns: GNUTLS_E_SUCCESS on success (if keyid exists) and a negative error code on failure.

gnutls_openpgp_keyring_deinit

Function: void gnutls_openpgp_keyring_deinit (gnutls_openpgp_keyring_t keyring)

keyring: The structure to be initialized

This function will deinitialize a keyring structure.

gnutls_openpgp_keyring_get_crt

Function: int gnutls_openpgp_keyring_get_crt (gnutls_openpgp_keyring_t ring, unsigned int idx, gnutls_openpgp_crt_t * cert)

ring: Holds the keyring.

idx: the index of the certificate to export

cert: An uninitialized gnutls_openpgp_crt_t structure

This function will extract an OpenPGP certificate from the given keyring. If the index given is out of range GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned. The returned structure needs to be deinited.

Returns: GNUTLS_E_SUCCESS on success, or an error code.

gnutls_openpgp_keyring_get_crt_count

Function: int gnutls_openpgp_keyring_get_crt_count (gnutls_openpgp_keyring_t ring)

ring: is an OpenPGP key ring

This function will return the number of OpenPGP certificates present in the given keyring.

Returns: the number of subkeys, or a negative error code on error.

gnutls_openpgp_keyring_import

Function: int gnutls_openpgp_keyring_import (gnutls_openpgp_keyring_t keyring, const gnutls_datum_t * data, gnutls_openpgp_crt_fmt_t format)

keyring: The structure to store the parsed key.

data: The RAW or BASE64 encoded keyring.

format: One of gnutls_openpgp_keyring_fmt elements.

This function will convert the given RAW or Base64 encoded keyring to the native gnutls_openpgp_keyring_t format. The output will be stored in ’keyring’.

Returns: GNUTLS_E_SUCCESS on success, or an error code.

gnutls_openpgp_keyring_init

Function: int gnutls_openpgp_keyring_init (gnutls_openpgp_keyring_t * keyring)

keyring: The structure to be initialized

This function will initialize an keyring structure.

Returns: GNUTLS_E_SUCCESS on success, or an error code.

gnutls_openpgp_privkey_deinit

Function: void gnutls_openpgp_privkey_deinit (gnutls_openpgp_privkey_t key)

key: The structure to be initialized

This function will deinitialize a key structure.

gnutls_openpgp_privkey_export

Function: int gnutls_openpgp_privkey_export (gnutls_openpgp_privkey_t key, gnutls_openpgp_crt_fmt_t format, const char * password, unsigned int flags, void * output_data, size_t * output_data_size)

key: Holds the key.

format: One of gnutls_openpgp_crt_fmt_t elements.

password: the password that will be used to encrypt the key. (unused for now)

flags: (0) for future compatibility

output_data: will contain the key base64 encoded or raw

output_data_size: holds the size of output_data (and will be replaced by the actual size of parameters)

This function will convert the given key to RAW or Base64 format. If the buffer provided is not long enough to hold the output, then GNUTLS_E_SHORT_MEMORY_BUFFER will be returned.

Returns: GNUTLS_E_SUCCESS on success, or an error code.

Since: 2.4.0

gnutls_openpgp_privkey_export_dsa_raw

Function: int gnutls_openpgp_privkey_export_dsa_raw (gnutls_openpgp_privkey_t pkey, gnutls_datum_t * p, gnutls_datum_t * q, gnutls_datum_t * g, gnutls_datum_t * y, gnutls_datum_t * x)

pkey: Holds the certificate

p: will hold the p

q: will hold the q

g: will hold the g

y: will hold the y

x: will hold the x

This function will export the DSA private key’s parameters found in the given certificate. The new parameters will be allocated using gnutls_malloc() and will be stored in the appropriate datum.

Returns: GNUTLS_E_SUCCESS on success, otherwise a negative error code.

Since: 2.4.0

gnutls_openpgp_privkey_export_rsa_raw

Function: int gnutls_openpgp_privkey_export_rsa_raw (gnutls_openpgp_privkey_t pkey, gnutls_datum_t * m, gnutls_datum_t * e, gnutls_datum_t * d, gnutls_datum_t * p, gnutls_datum_t * q, gnutls_datum_t * u)

pkey: Holds the certificate

m: will hold the modulus

e: will hold the public exponent

d: will hold the private exponent

p: will hold the first prime (p)

q: will hold the second prime (q)

u: will hold the coefficient

This function will export the RSA private key’s parameters found in the given structure. The new parameters will be allocated using gnutls_malloc() and will be stored in the appropriate datum.

Returns: GNUTLS_E_SUCCESS on success, otherwise a negative error code.

Since: 2.4.0

gnutls_openpgp_privkey_export_subkey_dsa_raw

Function: int gnutls_openpgp_privkey_export_subkey_dsa_raw (gnutls_openpgp_privkey_t pkey, unsigned int idx, gnutls_datum_t * p, gnutls_datum_t * q, gnutls_datum_t * g, gnutls_datum_t * y, gnutls_datum_t * x)

pkey: Holds the certificate

idx: Is the subkey index

p: will hold the p

q: will hold the q

g: will hold the g

y: will hold the y

x: will hold the x

This function will export the DSA private key’s parameters found in the given certificate. The new parameters will be allocated using gnutls_malloc() and will be stored in the appropriate datum.

Returns: GNUTLS_E_SUCCESS on success, otherwise a negative error code.

Since: 2.4.0

gnutls_openpgp_privkey_export_subkey_rsa_raw

Function: int gnutls_openpgp_privkey_export_subkey_rsa_raw (gnutls_openpgp_privkey_t pkey, unsigned int idx, gnutls_datum_t * m, gnutls_datum_t * e, gnutls_datum_t * d, gnutls_datum_t * p, gnutls_datum_t * q, gnutls_datum_t * u)

pkey: Holds the certificate

idx: Is the subkey index

m: will hold the modulus

e: will hold the public exponent

d: will hold the private exponent

p: will hold the first prime (p)

q: will hold the second prime (q)

u: will hold the coefficient

This function will export the RSA private key’s parameters found in the given structure. The new parameters will be allocated using gnutls_malloc() and will be stored in the appropriate datum.

Returns: GNUTLS_E_SUCCESS on success, otherwise a negative error code.

Since: 2.4.0

gnutls_openpgp_privkey_get_fingerprint

Function: int gnutls_openpgp_privkey_get_fingerprint (gnutls_openpgp_privkey_t key, void * fpr, size_t * fprlen)

key: the raw data that contains the OpenPGP secret key.

fpr: the buffer to save the fingerprint, must hold at least 20 bytes.

fprlen: the integer to save the length of the fingerprint.

Get the fingerprint of the OpenPGP key. Depends on the algorithm, the fingerprint can be 16 or 20 bytes.

Returns: On success, 0 is returned, or an error code.

Since: 2.4.0

gnutls_openpgp_privkey_get_key_id

Function: int gnutls_openpgp_privkey_get_key_id (gnutls_openpgp_privkey_t key, gnutls_openpgp_keyid_t keyid)

key: the structure that contains the OpenPGP secret key.

keyid: the buffer to save the keyid.

Get key-id.

Returns: the 64-bit keyID of the OpenPGP key.

Since: 2.4.0

gnutls_openpgp_privkey_get_pk_algorithm

Function: gnutls_pk_algorithm_t gnutls_openpgp_privkey_get_pk_algorithm (gnutls_openpgp_privkey_t key, unsigned int * bits)

key: is an OpenPGP key

bits: if bits is non null it will hold the size of the parameters’ in bits

This function will return the public key algorithm of an OpenPGP certificate.

If bits is non null, it should have enough size to hold the parameters size in bits. For RSA the bits returned is the modulus. For DSA the bits returned are of the public exponent.

Returns: a member of the gnutls_pk_algorithm_t enumeration on success, or a negative error code on error.

Since: 2.4.0

gnutls_openpgp_privkey_get_preferred_key_id

Function: int gnutls_openpgp_privkey_get_preferred_key_id (gnutls_openpgp_privkey_t key, gnutls_openpgp_keyid_t keyid)

key: the structure that contains the OpenPGP public key.

keyid: the struct to save the keyid.

Get the preferred key-id for the key.

Returns: the 64-bit preferred keyID of the OpenPGP key, or if it hasn’t been set it returns GNUTLS_E_INVALID_REQUEST .

gnutls_openpgp_privkey_get_revoked_status

Function: int gnutls_openpgp_privkey_get_revoked_status (gnutls_openpgp_privkey_t key)

key: the structure that contains the OpenPGP private key.

Get revocation status of key.

Returns: true (1) if the key has been revoked, or false (0) if it has not, or a negative error code indicates an error.

Since: 2.4.0

gnutls_openpgp_privkey_get_subkey_count

Function: int gnutls_openpgp_privkey_get_subkey_count (gnutls_openpgp_privkey_t key)

key: is an OpenPGP key

This function will return the number of subkeys present in the given OpenPGP certificate.

Returns: the number of subkeys, or a negative error code on error.

Since: 2.4.0

gnutls_openpgp_privkey_get_subkey_creation_time

Function: time_t gnutls_openpgp_privkey_get_subkey_creation_time (gnutls_openpgp_privkey_t key, unsigned int idx)

key: the structure that contains the OpenPGP private key.

idx: the subkey index

Get subkey creation time.

Returns: the timestamp when the OpenPGP key was created.

Since: 2.4.0

gnutls_openpgp_privkey_get_subkey_fingerprint

Function: int gnutls_openpgp_privkey_get_subkey_fingerprint (gnutls_openpgp_privkey_t key, unsigned int idx, void * fpr, size_t * fprlen)

key: the raw data that contains the OpenPGP secret key.

idx: the subkey index

fpr: the buffer to save the fingerprint, must hold at least 20 bytes.

fprlen: the integer to save the length of the fingerprint.

Get the fingerprint of an OpenPGP subkey. Depends on the algorithm, the fingerprint can be 16 or 20 bytes.

Returns: On success, 0 is returned, or an error code.

Since: 2.4.0

gnutls_openpgp_privkey_get_subkey_id

Function: int gnutls_openpgp_privkey_get_subkey_id (gnutls_openpgp_privkey_t key, unsigned int idx, gnutls_openpgp_keyid_t keyid)

key: the structure that contains the OpenPGP secret key.

idx: the subkey index

keyid: the buffer to save the keyid.

Get the key-id for the subkey.

Returns: the 64-bit keyID of the OpenPGP key.

Since: 2.4.0

gnutls_openpgp_privkey_get_subkey_idx

Function: int gnutls_openpgp_privkey_get_subkey_idx (gnutls_openpgp_privkey_t key, const gnutls_openpgp_keyid_t keyid)

key: the structure that contains the OpenPGP private key.

keyid: the keyid.

Get index of subkey.

Returns: the index of the subkey or a negative error value.

Since: 2.4.0

gnutls_openpgp_privkey_get_subkey_pk_algorithm

Function: gnutls_pk_algorithm_t gnutls_openpgp_privkey_get_subkey_pk_algorithm (gnutls_openpgp_privkey_t key, unsigned int idx, unsigned int * bits)

key: is an OpenPGP key

idx: is the subkey index

bits: if bits is non null it will hold the size of the parameters’ in bits

This function will return the public key algorithm of a subkey of an OpenPGP certificate.

If bits is non null, it should have enough size to hold the parameters size in bits. For RSA the bits returned is the modulus. For DSA the bits returned are of the public exponent.

Returns: a member of the gnutls_pk_algorithm_t enumeration on success, or a negative error code on error.

Since: 2.4.0

gnutls_openpgp_privkey_get_subkey_revoked_status

Function: int gnutls_openpgp_privkey_get_subkey_revoked_status (gnutls_openpgp_privkey_t                                                   key, unsigned int idx)

key: the structure that contains the OpenPGP private key.

idx: is the subkey index

Get revocation status of key.

Returns: true (1) if the key has been revoked, or false (0) if it has not, or a negative error code indicates an error.

Since: 2.4.0

gnutls_openpgp_privkey_import

Function: int gnutls_openpgp_privkey_import (gnutls_openpgp_privkey_t key, const gnutls_datum_t * data, gnutls_openpgp_crt_fmt_t format, const char * password, unsigned int flags)

key: The structure to store the parsed key.

data: The RAW or BASE64 encoded key.

format: One of gnutls_openpgp_crt_fmt_t elements.

password: not used for now

flags: should be (0)

This function will convert the given RAW or Base64 encoded key to the native gnutls_openpgp_privkey_t format. The output will be stored in ’key’.

Returns: GNUTLS_E_SUCCESS on success, or an error code.

gnutls_openpgp_privkey_init

Function: int gnutls_openpgp_privkey_init (gnutls_openpgp_privkey_t * key)

key: The structure to be initialized

This function will initialize an OpenPGP key structure.

Returns: GNUTLS_E_SUCCESS on success, or an error code.

gnutls_openpgp_privkey_sec_param

Function: gnutls_sec_param_t gnutls_openpgp_privkey_sec_param (gnutls_openpgp_privkey_t key)

key: a key structure

This function will return the security parameter appropriate with this private key.

Returns: On success, a valid security parameter is returned otherwise GNUTLS_SEC_PARAM_UNKNOWN is returned.

Since: 2.12.0

gnutls_openpgp_privkey_set_preferred_key_id

Function: int gnutls_openpgp_privkey_set_preferred_key_id (gnutls_openpgp_privkey_t key, const gnutls_openpgp_keyid_t                                              keyid)

key: the structure that contains the OpenPGP public key.

keyid: the selected keyid

This allows setting a preferred key id for the given certificate. This key will be used by functions that involve key handling.

Returns: On success, 0 is returned, or an error code.

gnutls_openpgp_set_recv_key_function

Function: void gnutls_openpgp_set_recv_key_function (gnutls_session_t session, gnutls_openpgp_recv_key_func func)

session: a TLS session

func: the callback

This funtion will set a key retrieval function for OpenPGP keys. This callback is only useful in server side, and will be used if the peer sent a key fingerprint instead of a full key.

PKCS 12 API

The following functions are to be used for PKCS 12 handling. Their prototypes lie in gnutls/pkcs12.h.

gnutls_pkcs12_bag_decrypt

Function: int gnutls_pkcs12_bag_decrypt (gnutls_pkcs12_bag_t bag, const char * pass)

bag: The bag

pass: The password used for encryption, must be ASCII.

This function will decrypt the given encrypted bag and return 0 on success.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

gnutls_pkcs12_bag_deinit

Function: void gnutls_pkcs12_bag_deinit (gnutls_pkcs12_bag_t bag)

bag: The structure to be initialized

This function will deinitialize a PKCS12 Bag structure.

gnutls_pkcs12_bag_encrypt

Function: int gnutls_pkcs12_bag_encrypt (gnutls_pkcs12_bag_t bag, const char * pass, unsigned int flags)

bag: The bag

pass: The password used for encryption, must be ASCII

flags: should be one of gnutls_pkcs_encrypt_flags_t elements bitwise or’d

This function will encrypt the given bag.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

gnutls_pkcs12_bag_get_count

Function: int gnutls_pkcs12_bag_get_count (gnutls_pkcs12_bag_t bag)

bag: The bag

This function will return the number of the elements withing the bag.

Returns: Number of elements in bag, or an negative error code on error.

gnutls_pkcs12_bag_get_data

Function: int gnutls_pkcs12_bag_get_data (gnutls_pkcs12_bag_t bag, int indx, gnutls_datum_t * data)

bag: The bag

indx: The element of the bag to get the data from

data: where the bag’s data will be. Should be treated as constant.

This function will return the bag’s data. The data is a constant that is stored into the bag. Should not be accessed after the bag is deleted.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_pkcs12_bag_get_friendly_name

Function: int gnutls_pkcs12_bag_get_friendly_name (gnutls_pkcs12_bag_t bag, int indx, char ** name)

bag: The bag

indx: The bag’s element to add the id

name: will hold a pointer to the name (to be treated as const)

This function will return the friendly name, of the specified bag element. The key ID is usually used to distinguish the local private key and the certificate pair.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value. or a negative error code on error.

gnutls_pkcs12_bag_get_key_id

Function: int gnutls_pkcs12_bag_get_key_id (gnutls_pkcs12_bag_t bag, int indx, gnutls_datum_t * id)

bag: The bag

indx: The bag’s element to add the id

id: where the ID will be copied (to be treated as const)

This function will return the key ID, of the specified bag element. The key ID is usually used to distinguish the local private key and the certificate pair.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value. or a negative error code on error.

gnutls_pkcs12_bag_get_type

Function: gnutls_pkcs12_bag_type_t gnutls_pkcs12_bag_get_type (gnutls_pkcs12_bag_t bag, int indx)

bag: The bag

indx: The element of the bag to get the type

This function will return the bag’s type.

Returns: One of the gnutls_pkcs12_bag_type_t enumerations.

gnutls_pkcs12_bag_init

Function: int gnutls_pkcs12_bag_init (gnutls_pkcs12_bag_t * bag)

bag: The structure to be initialized

This function will initialize a PKCS12 bag structure. PKCS12 Bags usually contain private keys, lists of X.509 Certificates and X.509 Certificate revocation lists.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_pkcs12_bag_set_crl

Function: int gnutls_pkcs12_bag_set_crl (gnutls_pkcs12_bag_t bag, gnutls_x509_crl_t crl)

bag: The bag

crl: the CRL to be copied.

This function will insert the given CRL into the bag. This is just a wrapper over gnutls_pkcs12_bag_set_data() .

Returns: the index of the added bag on success, or a negative error code on failure.

gnutls_pkcs12_bag_set_crt

Function: int gnutls_pkcs12_bag_set_crt (gnutls_pkcs12_bag_t bag, gnutls_x509_crt_t crt)

bag: The bag

crt: the certificate to be copied.

This function will insert the given certificate into the bag. This is just a wrapper over gnutls_pkcs12_bag_set_data() .

Returns: the index of the added bag on success, or a negative value on failure.

gnutls_pkcs12_bag_set_data

Function: int gnutls_pkcs12_bag_set_data (gnutls_pkcs12_bag_t bag, gnutls_pkcs12_bag_type_t type, const gnutls_datum_t * data)

bag: The bag

type: The data’s type

data: the data to be copied.

This function will insert the given data of the given type into the bag.

Returns: the index of the added bag on success, or a negative value on error.

gnutls_pkcs12_bag_set_friendly_name

Function: int gnutls_pkcs12_bag_set_friendly_name (gnutls_pkcs12_bag_t bag, int indx, const char * name)

bag: The bag

indx: The bag’s element to add the id

name: the name

This function will add the given key friendly name, to the specified, by the index, bag element. The name will be encoded as a ’Friendly name’ bag attribute, which is usually used to set a user name to the local private key and the certificate pair.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value. or a negative error code on error.

gnutls_pkcs12_bag_set_key_id

Function: int gnutls_pkcs12_bag_set_key_id (gnutls_pkcs12_bag_t bag, int indx, const gnutls_datum_t * id)

bag: The bag

indx: The bag’s element to add the id

id: the ID

This function will add the given key ID, to the specified, by the index, bag element. The key ID will be encoded as a ’Local key identifier’ bag attribute, which is usually used to distinguish the local private key and the certificate pair.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value. or a negative error code on error.

gnutls_pkcs12_deinit

Function: void gnutls_pkcs12_deinit (gnutls_pkcs12_t pkcs12)

pkcs12: The structure to be initialized

This function will deinitialize a PKCS12 structure.

gnutls_pkcs12_export

Function: int gnutls_pkcs12_export (gnutls_pkcs12_t pkcs12, gnutls_x509_crt_fmt_t format, void * output_data, size_t * output_data_size)

pkcs12: Holds the pkcs12 structure

format: the format of output params. One of PEM or DER.

output_data: will contain a structure PEM or DER encoded

output_data_size: holds the size of output_data (and will be replaced by the actual size of parameters)

This function will export the pkcs12 structure to DER or PEM format.

If the buffer provided is not long enough to hold the output, then *output_data_size will be updated and GNUTLS_E_SHORT_MEMORY_BUFFER will be returned.

If the structure is PEM encoded, it will have a header of "BEGIN PKCS12".

Returns: In case of failure a negative error code will be returned, and 0 on success.

gnutls_pkcs12_generate_mac

Function: int gnutls_pkcs12_generate_mac (gnutls_pkcs12_t pkcs12, const char * pass)

pkcs12: should contain a gnutls_pkcs12_t structure

pass: The password for the MAC

This function will generate a MAC for the PKCS12 structure.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_pkcs12_get_bag

Function: int gnutls_pkcs12_get_bag (gnutls_pkcs12_t pkcs12, int indx, gnutls_pkcs12_bag_t bag)

pkcs12: should contain a gnutls_pkcs12_t structure

indx: contains the index of the bag to extract

bag: An initialized bag, where the contents of the bag will be copied

This function will return a Bag from the PKCS12 structure.

After the last Bag has been read GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_pkcs12_import

Function: int gnutls_pkcs12_import (gnutls_pkcs12_t pkcs12, const gnutls_datum_t * data, gnutls_x509_crt_fmt_t format, unsigned int flags)

pkcs12: The structure to store the parsed PKCS12.

data: The DER or PEM encoded PKCS12.

format: One of DER or PEM

flags: an ORed sequence of gnutls_privkey_pkcs8_flags

This function will convert the given DER or PEM encoded PKCS12 to the native gnutls_pkcs12_t format. The output will be stored in ’pkcs12’.

If the PKCS12 is PEM encoded it should have a header of "PKCS12".

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_pkcs12_init

Function: int gnutls_pkcs12_init (gnutls_pkcs12_t * pkcs12)

pkcs12: The structure to be initialized

This function will initialize a PKCS12 structure. PKCS12 structures usually contain lists of X.509 Certificates and X.509 Certificate revocation lists.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_pkcs12_set_bag

Function: int gnutls_pkcs12_set_bag (gnutls_pkcs12_t pkcs12, gnutls_pkcs12_bag_t bag)

pkcs12: should contain a gnutls_pkcs12_t structure

bag: An initialized bag

This function will insert a Bag into the PKCS12 structure.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_pkcs12_verify_mac

Function: int gnutls_pkcs12_verify_mac (gnutls_pkcs12_t pkcs12, const char * pass)

pkcs12: should contain a gnutls_pkcs12_t structure

pass: The password for the MAC

This function will verify the MAC for the PKCS12 structure.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Hardware token via PKCS 11 API

The following functions are to be used for PKCS 11 handling. Their prototypes lie in gnutls/pkcs11.h.

gnutls_pkcs11_add_provider

Function: int gnutls_pkcs11_add_provider (const char * name, const char * params)

name: The filename of the module

params: should be NULL

This function will load and add a PKCS 11 module to the module list used in gnutls. After this function is called the module will be used for PKCS 11 operations.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.12.0

gnutls_pkcs11_copy_secret_key

Function: int gnutls_pkcs11_copy_secret_key (const char * token_url, gnutls_datum_t * key, const char * label, unsigned int key_usage, unsigned int flags)

token_url: A PKCS 11 URL specifying a token

key: The raw key

label: A name to be used for the stored data

key_usage: One of GNUTLS_KEY_*

flags: One of GNUTLS_PKCS11_OBJ_FLAG_*

This function will copy a raw secret (symmetric) key into a PKCS 11 token specified by a URL. The key can be marked as sensitive or not.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.12.0

gnutls_pkcs11_copy_x509_crt

Function: int gnutls_pkcs11_copy_x509_crt (const char * token_url, gnutls_x509_crt_t crt, const char * label, unsigned int flags)

token_url: A PKCS 11 URL specifying a token

crt: A certificate

label: A name to be used for the stored data

flags: One of GNUTLS_PKCS11_OBJ_FLAG_*

This function will copy a certificate into a PKCS 11 token specified by a URL. The certificate can be marked as trusted or not.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.12.0

gnutls_pkcs11_copy_x509_privkey

Function: int gnutls_pkcs11_copy_x509_privkey (const char * token_url, gnutls_x509_privkey_t key, const char * label, unsigned int key_usage, unsigned int flags)

token_url: A PKCS 11 URL specifying a token

key: A private key

label: A name to be used for the stored data

key_usage: One of GNUTLS_KEY_*

flags: One of GNUTLS_PKCS11_OBJ_* flags

This function will copy a private key into a PKCS 11 token specified by a URL. It is highly recommended flags to contain GNUTLS_PKCS11_OBJ_FLAG_MARK_SENSITIVE unless there is a strong reason not to.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.12.0

gnutls_pkcs11_deinit

Function: void gnutls_pkcs11_deinit ( void)

This function will deinitialize the PKCS 11 subsystem in gnutls.

Since: 2.12.0

gnutls_pkcs11_delete_url

Function: int gnutls_pkcs11_delete_url (const char * object_url, unsigned int flags)

object_url: The URL of the object to delete.

flags: One of GNUTLS_PKCS11_OBJ_* flags

This function will delete objects matching the given URL. Note that not all tokens support the delete operation.

Returns: On success, the number of objects deleted is returned, otherwise a negative error value.

Since: 2.12.0

gnutls_pkcs11_init

Function: int gnutls_pkcs11_init (unsigned int flags, const char * deprecated_config_file)

flags: GNUTLS_PKCS11_FLAG_MANUAL or GNUTLS_PKCS11_FLAG_AUTO

deprecated_config_file: either NULL or the location of a deprecated configuration file

This function will initialize the PKCS 11 subsystem in gnutls. It will read configuration files if GNUTLS_PKCS11_FLAG_AUTO is used or allow you to independently load PKCS 11 modules using gnutls_pkcs11_add_provider() if GNUTLS_PKCS11_FLAG_MANUAL is specified.

Normally you don’t need to call this function since it is being called by gnutls_global_init() using the GNUTLS_PKCS11_FLAG_AUTO . If other option is required then it must be called before it.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.12.0

gnutls_pkcs11_obj_deinit

Function: void gnutls_pkcs11_obj_deinit (gnutls_pkcs11_obj_t obj)

obj: The structure to be initialized

This function will deinitialize a certificate structure.

Since: 2.12.0

gnutls_pkcs11_obj_export

Function: int gnutls_pkcs11_obj_export (gnutls_pkcs11_obj_t obj, void * output_data, size_t * output_data_size)

obj: Holds the object

output_data: will contain a certificate PEM or DER encoded

output_data_size: holds the size of output_data (and will be replaced by the actual size of parameters)

This function will export the PKCS11 object data. It is normal for data to be inaccesible and in that case GNUTLS_E_INVALID_REQUEST will be returned.

If the buffer provided is not long enough to hold the output, then *output_data_size is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will be returned.

If the structure is PEM encoded, it will have a header of "BEGIN CERTIFICATE".

Returns: In case of failure a negative error code will be returned, and GNUTLS_E_SUCCESS (0) on success.

Since: 2.12.0

gnutls_pkcs11_obj_export_url

Function: int gnutls_pkcs11_obj_export_url (gnutls_pkcs11_obj_t obj, gnutls_pkcs11_url_type_t detailed, char ** url)

obj: Holds the PKCS 11 certificate

detailed: non zero if a detailed URL is required

url: will contain an allocated url

This function will export a URL identifying the given certificate.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.12.0

gnutls_pkcs11_obj_get_info

Function: int gnutls_pkcs11_obj_get_info (gnutls_pkcs11_obj_t crt, gnutls_pkcs11_obj_info_t itype, void * output, size_t * output_size)

crt: should contain a gnutls_pkcs11_obj_t structure

itype: Denotes the type of information requested

output: where output will be stored

output_size: contains the maximum size of the output and will be overwritten with actual

This function will return information about the PKCS11 certificate such as the label, id as well as token information where the key is stored. When output is text it returns null terminated string although output_size contains the size of the actual data only.

Returns: GNUTLS_E_SUCCESS (0) on success or a negative error code on error.

Since: 2.12.0

gnutls_pkcs11_obj_get_type

Function: gnutls_pkcs11_obj_type_t gnutls_pkcs11_obj_get_type (gnutls_pkcs11_obj_t obj)

obj: Holds the PKCS 11 object

This function will return the type of the certificate being stored in the structure.

Returns: The type of the certificate.

Since: 2.12.0

gnutls_pkcs11_obj_import_url

Function: int gnutls_pkcs11_obj_import_url (gnutls_pkcs11_obj_t cert, const char * url, unsigned int flags)

cert: The structure to store the parsed certificate

url: a PKCS 11 url identifying the key

flags: One of GNUTLS_PKCS11_OBJ_* flags

This function will "import" a PKCS 11 URL identifying a certificate key to the gnutls_pkcs11_obj_t structure. This does not involve any parsing (such as X.509 or OpenPGP) since the gnutls_pkcs11_obj_t is format agnostic. Only data are transferred.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.12.0

gnutls_pkcs11_obj_init

Function: int gnutls_pkcs11_obj_init (gnutls_pkcs11_obj_t * obj)

obj: The structure to be initialized

This function will initialize a pkcs11 certificate structure.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.12.0

gnutls_pkcs11_obj_list_import_url

Function: int gnutls_pkcs11_obj_list_import_url (gnutls_pkcs11_obj_t * p_list, unsigned int * n_list, const char * url, gnutls_pkcs11_obj_attr_t attrs, unsigned int flags)

p_list: An uninitialized object list (may be NULL)

n_list: initially should hold the maximum size of the list. Will contain the actual size.

url: A PKCS 11 url identifying a set of objects

attrs: Attributes of type gnutls_pkcs11_obj_attr_t that can be used to limit output

flags: One of GNUTLS_PKCS11_OBJ_* flags

This function will initialize and set values to an object list by using all objects identified by a PKCS 11 URL.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.12.0

gnutls_pkcs11_privkey_deinit

Function: void gnutls_pkcs11_privkey_deinit (gnutls_pkcs11_privkey_t key)

key: The structure to be initialized

This function will deinitialize a private key structure.

gnutls_pkcs11_privkey_export_url

Function: int gnutls_pkcs11_privkey_export_url (gnutls_pkcs11_privkey_t key, gnutls_pkcs11_url_type_t detailed, char ** url)

key: Holds the PKCS 11 key

detailed: non zero if a detailed URL is required

url: will contain an allocated url

This function will export a URL identifying the given key.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_pkcs11_privkey_generate

Function: int gnutls_pkcs11_privkey_generate (const char* url, gnutls_pk_algorithm_t pk, unsigned int bits, const char* label, unsigned int flags)

url: a token URL

pk: the public key algorithm

bits: the security bits

label: a label

flags: should be zero

This function will generate a private key in the specified by the url token. The pivate key will be generate within the token and will not be exportable.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 3.0

gnutls_pkcs11_privkey_get_info

Function: int gnutls_pkcs11_privkey_get_info (gnutls_pkcs11_privkey_t pkey, gnutls_pkcs11_obj_info_t itype, void * output, size_t * output_size)

pkey: should contain a gnutls_pkcs11_privkey_t structure

itype: Denotes the type of information requested

output: where output will be stored

output_size: contains the maximum size of the output and will be overwritten with actual

This function will return information about the PKCS 11 private key such as the label, id as well as token information where the key is stored. When output is text it returns null terminated string although output_size contains the size of the actual data only.

Returns: GNUTLS_E_SUCCESS (0) on success or a negative error code on error.

gnutls_pkcs11_privkey_get_pk_algorithm

Function: int gnutls_pkcs11_privkey_get_pk_algorithm (gnutls_pkcs11_privkey_t key, unsigned int * bits)

key: should contain a gnutls_pkcs11_privkey_t structure

bits: if bits is non null it will hold the size of the parameters’ in bits

This function will return the public key algorithm of a private key.

Returns: a member of the gnutls_pk_algorithm_t enumeration on success, or a negative error code on error.

gnutls_pkcs11_privkey_import_url

Function: int gnutls_pkcs11_privkey_import_url (gnutls_pkcs11_privkey_t pkey, const char * url, unsigned int flags)

pkey: The structure to store the parsed key

url: a PKCS 11 url identifying the key

flags: sequence of GNUTLS_PKCS_PRIVKEY_*

This function will "import" a PKCS 11 URL identifying a private key to the gnutls_pkcs11_privkey_t structure. In reality since in most cases keys cannot be exported, the private key structure is being associated with the available operations on the token.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_pkcs11_privkey_init

Function: int gnutls_pkcs11_privkey_init (gnutls_pkcs11_privkey_t * key)

key: The structure to be initialized

This function will initialize an private key structure.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_pkcs11_reinit

Function: int gnutls_pkcs11_reinit ( void)

This function will reinitialize the PKCS 11 subsystem in gnutls. This is required by PKCS 11 when an application uses fork() . The reinitialization function must be called on the child.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 3.0

gnutls_pkcs11_set_pin_function

Function: void gnutls_pkcs11_set_pin_function (gnutls_pkcs11_pin_callback_t fn, void * userdata)

fn: The PIN callback, a gnutls_pkcs11_pin_callback_t() function.

userdata: data to be supplied to callback

This function will set a callback function to be used when a PIN is required for PKCS 11 operations. See gnutls_pkcs11_pin_callback_t() on how the callback should behave.

Since: 2.12.0

gnutls_pkcs11_set_token_function

Function: void gnutls_pkcs11_set_token_function (gnutls_pkcs11_token_callback_t fn, void * userdata)

fn: The token callback

userdata: data to be supplied to callback

This function will set a callback function to be used when a token needs to be inserted to continue PKCS 11 operations.

Since: 2.12.0

gnutls_pkcs11_token_get_flags

Function: int gnutls_pkcs11_token_get_flags (const char * url, unsigned int * flags)

url: should contain a PKCS 11 URL

flags: The output flags (GNUTLS_PKCS11_TOKEN_*)

This function will return information about the PKCS 11 token flags. The flags from the gnutls_pkcs11_token_info_t enumeration.

Returns: GNUTLS_E_SUCCESS (0) on success or a negative error code on error.

Since: 2.12.0

gnutls_pkcs11_token_get_info

Function: int gnutls_pkcs11_token_get_info (const char * url, gnutls_pkcs11_token_info_t ttype, void * output, size_t * output_size)

url: should contain a PKCS 11 URL

ttype: Denotes the type of information requested

output: where output will be stored

output_size: contains the maximum size of the output and will be overwritten with actual

This function will return information about the PKCS 11 token such as the label, id, etc.

Returns: GNUTLS_E_SUCCESS (0) on success or a negative error code on error.

Since: 2.12.0

gnutls_pkcs11_token_get_mechanism

Function: int gnutls_pkcs11_token_get_mechanism (const char * url, unsigned int idx, unsigned long * mechanism)

url: should contain a PKCS 11 URL

idx: The index of the mechanism

mechanism: The PKCS 11 mechanism ID

This function will return the names of the supported mechanisms by the token. It should be called with an increasing index until it return GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE.

Returns: GNUTLS_E_SUCCESS (0) on success or a negative error code on error.

Since: 2.12.0

gnutls_pkcs11_token_get_url

Function: int gnutls_pkcs11_token_get_url (unsigned int seq, gnutls_pkcs11_url_type_t detailed, char ** url)

seq: sequence number starting from 0

detailed: non zero if a detailed URL is required

url: will contain an allocated url

This function will return the URL for each token available in system. The url has to be released using gnutls_free()

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE if the sequence number exceeds the available tokens, otherwise a negative error value.

Since: 2.12.0

gnutls_pkcs11_token_init

Function: int gnutls_pkcs11_token_init (const char * token_url, const char * so_pin, const char * label)

token_url: A PKCS 11 URL specifying a token

so_pin: Security Officer’s PIN

label: A name to be used for the token

This function will initialize (format) a token. If the token is at a factory defaults state the security officer’s PIN given will be set to be the default. Otherwise it should match the officer’s PIN.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_pkcs11_token_set_pin

Function: int gnutls_pkcs11_token_set_pin (const char * token_url, const char * oldpin, const char * newpin, unsigned int flags)

token_url: A PKCS 11 URL specifying a token

oldpin: old user’s PIN

newpin: new user’s PIN

flags: one of gnutls_pkcs11_pin_flag_t .

This function will modify or set a user’s PIN for the given token. If it is called to set a user pin for first time the oldpin must be NULL.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_pkcs11_type_get_name

Function: const char * gnutls_pkcs11_type_get_name (gnutls_pkcs11_obj_type_t type)

type: Holds the PKCS 11 object type, a gnutls_pkcs11_obj_type_t .

This function will return a human readable description of the PKCS11 object type obj . It will return "Unknown" for unknown types.

Returns: human readable string labeling the PKCS11 object type type .

Since: 2.12.0

gnutls_x509_crt_import_pkcs11

Function: int gnutls_x509_crt_import_pkcs11 (gnutls_x509_crt_t crt, gnutls_pkcs11_obj_t pkcs11_crt)

crt: A certificate of type gnutls_x509_crt_t

pkcs11_crt: A PKCS 11 object that contains a certificate

This function will import a PKCS 11 certificate to a gnutls_x509_crt_t structure.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.12.0

gnutls_x509_crt_import_pkcs11_url

Function: int gnutls_x509_crt_import_pkcs11_url (gnutls_x509_crt_t crt, const char * url, unsigned int flags)

crt: A certificate of type gnutls_x509_crt_t

url: A PKCS 11 url

flags: One of GNUTLS_PKCS11_OBJ_* flags

This function will import a PKCS 11 certificate directly from a token without involving the gnutls_pkcs11_obj_t structure. This function will fail if the certificate stored is not of X.509 type.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.12.0

gnutls_x509_crt_list_import_pkcs11

Function: int gnutls_x509_crt_list_import_pkcs11 (gnutls_x509_crt_t * certs, unsigned int cert_max, gnutls_pkcs11_obj_t * const objs, unsigned int flags)

certs: A list of certificates of type gnutls_x509_crt_t

cert_max: The maximum size of the list

objs: A list of PKCS 11 objects

flags: 0 for now

This function will import a PKCS 11 certificate list to a list of gnutls_x509_crt_t structure. These must not be initialized.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.12.0

Abstract key API

The following functions are to be used for abstract key handling. Their prototypes lie in gnutls/abstract.h.

gnutls_certificate_set_key

Function: int gnutls_certificate_set_key (gnutls_certificate_credentials_t res, const char** names, int names_size, gnutls_pcert_st * pcert_list, int pcert_list_size, gnutls_privkey_t key)

res: is a gnutls_certificate_credentials_t structure.

names: is an array of DNS name of the certificate (NULL if none)

names_size: holds the size of the names list

pcert_list: contains a certificate list (path) for the specified private key

pcert_list_size: holds the size of the certificate list

key: is a gnutls_x509_privkey_t key

This function sets a certificate/private key pair in the gnutls_certificate_credentials_t structure. This function may be called more than once, in case multiple keys/certificates exist for the server. For clients that wants to send more than its own end entity certificate (e.g., also an intermediate CA cert) then put the certificate chain in pcert_list . The pcert_list and key will become part of the credentials structure and must not be deallocated. They will be automatically deallocated when res is deinitialized.

Returns: GNUTLS_E_SUCCESS (0) on success, or a negative error code.

Since: 3.0

gnutls_certificate_set_retrieve_function2

Function: void gnutls_certificate_set_retrieve_function2 (gnutls_certificate_credentials_t cred, gnutls_certificate_retrieve_function2 * func)

cred: is a gnutls_certificate_credentials_t structure.

func: is the callback function

This function sets a callback to be called in order to retrieve the certificate to be used in the handshake.

The callback’s function prototype is: int (*callback)(gnutls_session_t, const gnutls_datum_t* req_ca_dn, int nreqs, const gnutls_pk_algorithm_t* pk_algos, int pk_algos_length, gnutls_pcert_st** pcert, unsigned int *pcert_length, gnutls_privkey_t * pkey);

req_ca_cert is only used in X.509 certificates. Contains a list with the CA names that the server considers trusted. Normally we should send a certificate that is signed by one of these CAs. These names are DER encoded. To get a more meaningful value use the function gnutls_x509_rdn_get() .

pk_algos contains a list with server’s acceptable signature algorithms. The certificate returned should support the server’s given algorithms.

pcert should contain a single certificate and public or a list of them.

pcert_length is the size of the previous list.

pkey is the private key.

If the callback function is provided then gnutls will call it, in the handshake, after the certificate request message has been received.

In server side pk_algos and req_ca_dn are NULL.

The callback function should set the certificate list to be sent, and return 0 on success. If no certificate was selected then the number of certificates should be set to zero. The value (-1) indicates error and the handshake will be terminated.

Since: 3.0

gnutls_pcert_deinit

Function: void gnutls_pcert_deinit (gnutls_pcert_st * pcert)

pcert: The structure to be deinitialized

This function will deinitialize a pcert structure.

Since: 3.0

gnutls_pcert_import_openpgp

Function: int gnutls_pcert_import_openpgp (gnutls_pcert_st* pcert, gnutls_openpgp_crt_t crt, unsigned int flags)

pcert: The pcert structure

crt: The raw certificate to be imported

flags: zero for now

This convenience function will import the given certificate to a gnutls_pcert_st structure. The structure must be deinitialized afterwards using gnutls_pcert_deinit() ;

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 3.0

gnutls_pcert_import_openpgp_raw

Function: int gnutls_pcert_import_openpgp_raw (gnutls_pcert_st * pcert, const gnutls_datum_t* cert, gnutls_openpgp_crt_fmt_t format, gnutls_openpgp_keyid_t keyid, unsigned int flags)

pcert: The pcert structure

cert: The raw certificate to be imported

format: The format of the certificate

keyid: The key ID to use (NULL for the master key)

flags: zero for now

This convenience function will import the given certificate to a gnutls_pcert_st structure. The structure must be deinitialized afterwards using gnutls_pcert_deinit() ;

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 3.0

gnutls_pcert_import_x509

Function: int gnutls_pcert_import_x509 (gnutls_pcert_st* pcert, gnutls_x509_crt_t crt, unsigned int flags)

pcert: The pcert structure

crt: The raw certificate to be imported

flags: zero for now

This convenience function will import the given certificate to a gnutls_pcert_st structure. The structure must be deinitialized afterwards using gnutls_pcert_deinit() ;

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 3.0

gnutls_pcert_import_x509_raw

Function: int gnutls_pcert_import_x509_raw (gnutls_pcert_st * pcert, const gnutls_datum_t* cert, gnutls_x509_crt_fmt_t format, unsigned int flags)

pcert: The pcert structure

cert: The raw certificate to be imported

format: The format of the certificate

flags: zero for now

This convenience function will import the given certificate to a gnutls_pcert_st structure. The structure must be deinitialized afterwards using gnutls_pcert_deinit() ;

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 3.0

gnutls_pcert_list_import_x509_raw

Function: int gnutls_pcert_list_import_x509_raw (gnutls_pcert_st * pcerts, unsigned int * pcert_max, const gnutls_datum_t * data, gnutls_x509_crt_fmt_t format, unsigned int flags)

pcerts: The structures to store the parsed certificate. Must not be initialized.

pcert_max: Initially must hold the maximum number of certs. It will be updated with the number of certs available.

data: The certificates.

format: One of DER or PEM.

flags: must be (0) or an OR’d sequence of gnutls_certificate_import_flags.

This function will convert the given PEM encoded certificate list to the native gnutls_x509_crt_t format. The output will be stored in certs . They will be automatically initialized.

If the Certificate is PEM encoded it should have a header of "X509 CERTIFICATE", or "CERTIFICATE".

Returns: the number of certificates read or a negative error value.

Since: 3.0

gnutls_privkey_decrypt_data

Function: int gnutls_privkey_decrypt_data (gnutls_privkey_t key, unsigned int flags, const gnutls_datum_t * ciphertext, gnutls_datum_t * plaintext)

key: Holds the key

flags: zero for now

ciphertext: holds the data to be decrypted

plaintext: will contain the decrypted data, allocated with gnutls_malloc()

This function will decrypt the given data using the algorithm supported by the private key.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.12.0

gnutls_privkey_deinit

Function: void gnutls_privkey_deinit (gnutls_privkey_t key)

key: The structure to be deinitialized

This function will deinitialize a private key structure.

Since: 2.12.0

gnutls_privkey_get_pk_algorithm

Function: int gnutls_privkey_get_pk_algorithm (gnutls_privkey_t key, unsigned int * bits)

key: should contain a gnutls_privkey_t structure

bits: If set will return the number of bits of the parameters (may be NULL)

This function will return the public key algorithm of a private key and if possible will return a number of bits that indicates the security parameter of the key.

Returns: a member of the gnutls_pk_algorithm_t enumeration on success, or a negative error code on error.

Since: 2.12.0

gnutls_privkey_get_type

Function: gnutls_privkey_type_t gnutls_privkey_get_type (gnutls_privkey_t key)

key: should contain a gnutls_privkey_t structure

This function will return the type of the private key. This is actually the type of the subsystem used to set this private key.

Returns: a member of the gnutls_privkey_type_t enumeration on success, or a negative error code on error.

Since: 2.12.0

gnutls_privkey_import_ext

Function: int gnutls_privkey_import_ext (gnutls_privkey_t pkey, gnutls_pk_algorithm_t pk, void* userdata, gnutls_privkey_sign_func sign_func, gnutls_privkey_decrypt_func decrypt_func, unsigned int flags)

pkey: The private key

pk: The public key algorithm

userdata: private data to be provided to the callbacks

sign_func: callback for signature operations

decrypt_func: callback for decryption operations

flags: Flags for the import

This function will associate the given callbacks with the gnutls_privkey_t structure. At least one of the two callbacks must be non-null.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 3.0

gnutls_privkey_import_openpgp

Function: int gnutls_privkey_import_openpgp (gnutls_privkey_t pkey, gnutls_openpgp_privkey_t key, unsigned int flags)

pkey: The private key

key: The private key to be imported

flags: Flags for the import

This function will import the given private key to the abstract gnutls_privkey_t structure.

The gnutls_openpgp_privkey_t object must not be deallocated during the lifetime of this structure. The subkey set as preferred will be used, or the master key otherwise.

flags might be zero or one of GNUTLS_PRIVKEY_IMPORT_AUTO_RELEASE and GNUTLS_PRIVKEY_IMPORT_COPY .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.12.0

gnutls_privkey_import_pkcs11

Function: int gnutls_privkey_import_pkcs11 (gnutls_privkey_t pkey, gnutls_pkcs11_privkey_t key, unsigned int flags)

pkey: The private key

key: The private key to be imported

flags: Flags for the import

This function will import the given private key to the abstract gnutls_privkey_t structure.

The gnutls_pkcs11_privkey_t object must not be deallocated during the lifetime of this structure.

flags might be zero or one of GNUTLS_PRIVKEY_IMPORT_AUTO_RELEASE and GNUTLS_PRIVKEY_IMPORT_COPY .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.12.0

gnutls_privkey_import_x509

Function: int gnutls_privkey_import_x509 (gnutls_privkey_t pkey, gnutls_x509_privkey_t key, unsigned int flags)

pkey: The private key

key: The private key to be imported

flags: Flags for the import

This function will import the given private key to the abstract gnutls_privkey_t structure.

The gnutls_x509_privkey_t object must not be deallocated during the lifetime of this structure.

flags might be zero or one of GNUTLS_PRIVKEY_IMPORT_AUTO_RELEASE and GNUTLS_PRIVKEY_IMPORT_COPY .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.12.0

gnutls_privkey_init

Function: int gnutls_privkey_init (gnutls_privkey_t * key)

key: The structure to be initialized

This function will initialize an private key structure.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.12.0

gnutls_privkey_sign_data

Function: int gnutls_privkey_sign_data (gnutls_privkey_t signer, gnutls_digest_algorithm_t hash, unsigned int flags, const gnutls_datum_t * data, gnutls_datum_t * signature)

signer: Holds the key

hash: should be a digest algorithm

flags: should be 0 for now

data: holds the data to be signed

signature: will contain the signature allocate with gnutls_malloc()

This function will sign the given data using a signature algorithm supported by the private key. Signature algorithms are always used together with a hash functions. Different hash functions may be used for the RSA algorithm, but only the SHA family for the DSA keys.

Use gnutls_pubkey_get_preferred_hash_algorithm() to determine the hash algorithm.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.12.0

gnutls_privkey_sign_hash

Function: int gnutls_privkey_sign_hash (gnutls_privkey_t signer, gnutls_digest_algorithm_t hash_algo, unsigned int flags, const gnutls_datum_t * hash_data, gnutls_datum_t * signature)

signer: Holds the signer’s key

hash_algo: The hash algorithm used

flags: zero for now

hash_data: holds the data to be signed

signature: will contain newly allocated signature

This function will sign the given hashed data using a signature algorithm supported by the private key. Signature algorithms are always used together with a hash functions. Different hash functions may be used for the RSA algorithm, but only SHA-XXX for the DSA keys.

Use gnutls_pubkey_get_preferred_hash_algorithm() to determine the hash algorithm.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.12.0

gnutls_pubkey_deinit

Function: void gnutls_pubkey_deinit (gnutls_pubkey_t key)

key: The structure to be deinitialized

This function will deinitialize a public key structure.

Since: 2.12.0

gnutls_pubkey_encrypt_data

Function: int gnutls_pubkey_encrypt_data (gnutls_pubkey_t key, unsigned int flags, const gnutls_datum_t * plaintext, gnutls_datum_t * ciphertext)

key: Holds the public key

flags: should be 0 for now

plaintext: The data to be encrypted

ciphertext: contains the encrypted data

This function will encrypt the given data, using the public key.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 3.0

gnutls_pubkey_export

Function: int gnutls_pubkey_export (gnutls_pubkey_t key, gnutls_x509_crt_fmt_t format, void * output_data, size_t * output_data_size)

key: Holds the certificate

format: the format of output params. One of PEM or DER.

output_data: will contain a certificate PEM or DER encoded

output_data_size: holds the size of output_data (and will be replaced by the actual size of parameters)

This function will export the public key to DER or PEM format. The contents of the exported data is the SubjectPublicKeyInfo X.509 structure.

If the buffer provided is not long enough to hold the output, then *output_data_size is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will be returned.

If the structure is PEM encoded, it will have a header of "BEGIN CERTIFICATE".

Returns: In case of failure a negative error code will be returned, and 0 on success.

Since: 2.12.0

gnutls_pubkey_get_key_id

Function: int gnutls_pubkey_get_key_id (gnutls_pubkey_t key, unsigned int flags, unsigned char * output_data, size_t * output_data_size)

key: Holds the public key

flags: should be 0 for now

output_data: will contain the key ID

output_data_size: holds the size of output_data (and will be replaced by the actual size of parameters)

This function will return a unique ID the depends on the public key parameters. This ID can be used in checking whether a certificate corresponds to the given public key.

If the buffer provided is not long enough to hold the output, then *output_data_size is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will be returned. The output will normally be a SHA-1 hash output, which is 20 bytes.

Returns: In case of failure a negative error code will be returned, and 0 on success.

Since: 2.12.0

gnutls_pubkey_get_key_usage

Function: int gnutls_pubkey_get_key_usage (gnutls_pubkey_t key, unsigned int * usage)

key: should contain a gnutls_pubkey_t structure

usage: If set will return the number of bits of the parameters (may be NULL)

This function will return the key usage of the public key.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.12.0

gnutls_pubkey_get_openpgp_key_id

Function: int gnutls_pubkey_get_openpgp_key_id (gnutls_pubkey_t key, unsigned int flags, unsigned char * output_data, size_t * output_data_size, unsigned int * subkey)

key: Holds the public key

flags: should be 0 for now

output_data: will contain the key ID

output_data_size: holds the size of output_data (and will be replaced by the actual size of parameters)

subkey: Will be non zero if the key ID corresponds to a subkey

This function will return a unique ID the depends on the public key parameters. This ID can be used in checking whether a certificate corresponds to the given public key.

If the buffer provided is not long enough to hold the output, then *output_data_size is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will be returned. The output will normally be a SHA-1 hash output, which is 20 bytes.

Returns: In case of failure a negative error code will be returned, and 0 on success.

Since: 3.0

gnutls_pubkey_get_pk_algorithm

Function: int gnutls_pubkey_get_pk_algorithm (gnutls_pubkey_t key, unsigned int * bits)

key: should contain a gnutls_pubkey_t structure

bits: If set will return the number of bits of the parameters (may be NULL)

This function will return the public key algorithm of a public key and if possible will return a number of bits that indicates the security parameter of the key.

Returns: a member of the gnutls_pk_algorithm_t enumeration on success, or a negative error code on error.

Since: 2.12.0

gnutls_pubkey_get_pk_dsa_raw

Function: int gnutls_pubkey_get_pk_dsa_raw (gnutls_pubkey_t key, gnutls_datum_t * p, gnutls_datum_t * q, gnutls_datum_t * g, gnutls_datum_t * y)

key: Holds the public key

p: will hold the p

q: will hold the q

g: will hold the g

y: will hold the y

This function will export the DSA public key’s parameters found in the given certificate. The new parameters will be allocated using gnutls_malloc() and will be stored in the appropriate datum.

Returns: GNUTLS_E_SUCCESS on success, otherwise a negative error code.

Since: 2.12.0

gnutls_pubkey_get_pk_ecc_raw

Function: int gnutls_pubkey_get_pk_ecc_raw (gnutls_pubkey_t key, gnutls_ecc_curve_t * curve, gnutls_datum_t * x, gnutls_datum_t * y)

key: Holds the public key

curve: will hold the curve

x: will hold x

y: will hold y

This function will export the ECC public key’s parameters found in the given certificate. The new parameters will be allocated using gnutls_malloc() and will be stored in the appropriate datum.

Returns: GNUTLS_E_SUCCESS on success, otherwise a negative error code.

Since: 3.0

gnutls_pubkey_get_pk_ecc_x962

Function: int gnutls_pubkey_get_pk_ecc_x962 (gnutls_pubkey_t key, gnutls_datum_t* parameters, gnutls_datum_t * ecpoint)

key: Holds the public key

parameters: DER encoding of an ANSI X9.62 parameters

ecpoint: DER encoding of ANSI X9.62 ECPoint

This function will export the ECC public key’s parameters found in the given certificate. The new parameters will be allocated using gnutls_malloc() and will be stored in the appropriate datum.

Returns: GNUTLS_E_SUCCESS on success, otherwise a negative error code.

Since: 3.0

gnutls_pubkey_get_pk_rsa_raw

Function: int gnutls_pubkey_get_pk_rsa_raw (gnutls_pubkey_t key, gnutls_datum_t * m, gnutls_datum_t * e)

key: Holds the certificate

m: will hold the modulus

e: will hold the public exponent

This function will export the RSA public key’s parameters found in the given structure. The new parameters will be allocated using gnutls_malloc() and will be stored in the appropriate datum.

Returns: GNUTLS_E_SUCCESS on success, otherwise a negative error code.

Since: 2.12.0

gnutls_pubkey_get_preferred_hash_algorithm

Function: int gnutls_pubkey_get_preferred_hash_algorithm (gnutls_pubkey_t key, gnutls_digest_algorithm_t *                                             hash, unsigned int * mand)

key: Holds the certificate

hash: The result of the call with the hash algorithm used for signature

mand: If non zero it means that the algorithm MUST use this hash. May be NULL.

This function will read the certifcate and return the appropriate digest algorithm to use for signing with this certificate. Some certificates (i.e. DSA might not be able to sign without the preferred algorithm).

Returns: the 0 if the hash algorithm is found. A negative error code is returned on error.

Since: 2.12.0

gnutls_pubkey_get_verify_algorithm

Function: int gnutls_pubkey_get_verify_algorithm (gnutls_pubkey_t key, const gnutls_datum_t * signature, gnutls_digest_algorithm_t * hash)

key: Holds the certificate

signature: contains the signature

hash: The result of the call with the hash algorithm used for signature

This function will read the certifcate and the signed data to determine the hash algorithm used to generate the signature.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.12.0

gnutls_pubkey_import

Function: int gnutls_pubkey_import (gnutls_pubkey_t key, const gnutls_datum_t * data, gnutls_x509_crt_fmt_t format)

key: The structure to store the parsed public key.

data: The DER or PEM encoded certificate.

format: One of DER or PEM

This function will import the provided public key in a SubjectPublicKeyInfo X.509 structure to a native gnutls_pubkey_t structure. The output will be stored in key . If the public key is PEM encoded it should have a header of "PUBLIC KEY".

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.12.0

gnutls_pubkey_import_dsa_raw

Function: int gnutls_pubkey_import_dsa_raw (gnutls_pubkey_t key, const gnutls_datum_t * p, const gnutls_datum_t * q, const gnutls_datum_t * g, const gnutls_datum_t * y)

key: The structure to store the parsed key

p: holds the p

q: holds the q

g: holds the g

y: holds the y

This function will convert the given DSA raw parameters to the native gnutls_pubkey_t format. The output will be stored in key .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.12.0

gnutls_pubkey_import_ecc_raw

Function: int gnutls_pubkey_import_ecc_raw (gnutls_pubkey_t key, gnutls_ecc_curve_t curve, const gnutls_datum_t * x, const gnutls_datum_t * y)

key: The structure to store the parsed key

curve: holds the curve

x: holds the x

y: holds the y

This function will convert the given elliptic curve parameters to a gnutls_pubkey_t . The output will be stored in key .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 3.0

gnutls_pubkey_import_ecc_x962

Function: int gnutls_pubkey_import_ecc_x962 (gnutls_pubkey_t key, const gnutls_datum_t * parameters, const gnutls_datum_t * ecpoint)

key: The structure to store the parsed key

parameters: DER encoding of an ANSI X9.62 parameters

ecpoint: DER encoding of ANSI X9.62 ECPoint

This function will convert the given elliptic curve parameters to a gnutls_pubkey_t . The output will be stored in key .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 3.0

gnutls_pubkey_import_openpgp

Function: int gnutls_pubkey_import_openpgp (gnutls_pubkey_t key, gnutls_openpgp_crt_t crt, unsigned int flags)

key: The public key

crt: The certificate to be imported

flags: should be zero

Imports a public key from an openpgp key. This function will import the given public key to the abstract gnutls_pubkey_t structure. The subkey set as preferred will be imported or the master key otherwise.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.12.0

gnutls_pubkey_import_pkcs11

Function: int gnutls_pubkey_import_pkcs11 (gnutls_pubkey_t key, gnutls_pkcs11_obj_t obj, unsigned int flags)

key: The public key

obj: The parameters to be imported

flags: should be zero

Imports a public key from a pkcs11 key. This function will import the given public key to the abstract gnutls_pubkey_t structure.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.12.0

gnutls_pubkey_import_pkcs11_url

Function: int gnutls_pubkey_import_pkcs11_url (gnutls_pubkey_t key, const char * url, unsigned int flags)

key: A key of type gnutls_pubkey_t

url: A PKCS 11 url

flags: One of GNUTLS_PKCS11_OBJ_* flags

This function will import a PKCS 11 certificate to a gnutls_pubkey_t structure.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.12.0

gnutls_pubkey_import_privkey

Function: int gnutls_pubkey_import_privkey (gnutls_pubkey_t key, gnutls_privkey_t pkey, unsigned int usage, unsigned int flags)

key: The public key

pkey: The private key

usage: GNUTLS_KEY_* key usage flags.

flags: should be zero

Imports the public key from a private. This function will import the given public key to the abstract gnutls_pubkey_t structure.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.12.0

gnutls_pubkey_import_rsa_raw

Function: int gnutls_pubkey_import_rsa_raw (gnutls_pubkey_t key, const gnutls_datum_t * m, const gnutls_datum_t * e)

key: Is a structure will hold the parameters

m: holds the modulus

e: holds the public exponent

This function will replace the parameters in the given structure. The new parameters should be stored in the appropriate gnutls_datum.

Returns: GNUTLS_E_SUCCESS on success, or an negative error code.

Since: 2.12.0

gnutls_pubkey_import_x509

Function: int gnutls_pubkey_import_x509 (gnutls_pubkey_t key, gnutls_x509_crt_t crt, unsigned int flags)

key: The public key

crt: The certificate to be imported

flags: should be zero

This function will import the given public key to the abstract gnutls_pubkey_t structure.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.12.0

gnutls_pubkey_init

Function: int gnutls_pubkey_init (gnutls_pubkey_t * key)

key: The structure to be initialized

This function will initialize an public key structure.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.12.0

gnutls_pubkey_set_key_usage

Function: int gnutls_pubkey_set_key_usage (gnutls_pubkey_t key, unsigned int usage)

key: a certificate of type gnutls_x509_crt_t

usage: an ORed sequence of the GNUTLS_KEY_* elements.

This function will set the key usage flags of the public key. This is only useful if the key is to be exported to a certificate or certificate request.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.12.0

gnutls_pubkey_verify_data

Function: int gnutls_pubkey_verify_data (gnutls_pubkey_t pubkey, unsigned int flags, const gnutls_datum_t * data, const gnutls_datum_t * signature)

pubkey: Holds the public key

flags: should be 0 for now

data: holds the signed data

signature: contains the signature

This function will verify the given signed data, using the parameters from the certificate.

Returns: In case of a verification failure GNUTLS_E_PK_SIG_VERIFY_FAILED is returned, and zero or positive code on success.

Since: 2.12.0

gnutls_pubkey_verify_data2

Function: int gnutls_pubkey_verify_data2 (gnutls_pubkey_t pubkey, gnutls_sign_algorithm_t algo, unsigned int flags, const gnutls_datum_t * data, const gnutls_datum_t * signature)

pubkey: Holds the public key

algo: The signature algorithm used

flags: should be 0 for now

data: holds the signed data

signature: contains the signature

This function will verify the given signed data, using the parameters from the certificate.

Returns: In case of a verification failure GNUTLS_E_PK_SIG_VERIFY_FAILED is returned, and zero or positive code on success.

Since: 3.0

gnutls_pubkey_verify_hash

Function: int gnutls_pubkey_verify_hash (gnutls_pubkey_t key, unsigned int flags, const gnutls_datum_t * hash, const gnutls_datum_t * signature)

key: Holds the public key

flags: should be 0 for now

hash: holds the hash digest to be verified

signature: contains the signature

This function will verify the given signed digest, using the parameters from the public key.

Returns: In case of a verification failure GNUTLS_E_PK_SIG_VERIFY_FAILED is returned, and zero or positive code on success.

Since: 2.12.0

gnutls_x509_crl_privkey_sign

Function: int gnutls_x509_crl_privkey_sign (gnutls_x509_crl_t crl, gnutls_x509_crt_t issuer, gnutls_privkey_t issuer_key, gnutls_digest_algorithm_t dig, unsigned int flags)

crl: should contain a gnutls_x509_crl_t structure

issuer: is the certificate of the certificate issuer

issuer_key: holds the issuer’s private key

dig: The message digest to use. GNUTLS_DIG_SHA1 is the safe choice unless you know what you’re doing.

flags: must be 0

This function will sign the CRL with the issuer’s private key, and will copy the issuer’s information into the CRL.

This must be the last step in a certificate CRL since all the previously set parameters are now signed.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since 2.12.0

gnutls_x509_crq_privkey_sign

Function: int gnutls_x509_crq_privkey_sign (gnutls_x509_crq_t crq, gnutls_privkey_t key, gnutls_digest_algorithm_t dig, unsigned int flags)

crq: should contain a gnutls_x509_crq_t structure

key: holds a private key

dig: The message digest to use, i.e., GNUTLS_DIG_SHA1

flags: must be 0

This function will sign the certificate request with a private key. This must be the same key as the one used in gnutls_x509_crt_set_key() since a certificate request is self signed.

This must be the last step in a certificate request generation since all the previously set parameters are now signed.

Returns: GNUTLS_E_SUCCESS on success, otherwise a negative error code. GNUTLS_E_ASN1_VALUE_NOT_FOUND is returned if you didn’t set all information in the certificate request (e.g., the version using gnutls_x509_crq_set_version() ).

Since: 2.12.0

gnutls_x509_crq_set_pubkey

Function: int gnutls_x509_crq_set_pubkey (gnutls_x509_crq_t crq, gnutls_pubkey_t key)

crq: should contain a gnutls_x509_crq_t structure

key: holds a public key

This function will set the public parameters from the given public key to the request.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.12.0

gnutls_x509_crt_privkey_sign

Function: int gnutls_x509_crt_privkey_sign (gnutls_x509_crt_t crt, gnutls_x509_crt_t issuer, gnutls_privkey_t issuer_key, gnutls_digest_algorithm_t dig, unsigned int flags)

crt: a certificate of type gnutls_x509_crt_t

issuer: is the certificate of the certificate issuer

issuer_key: holds the issuer’s private key

dig: The message digest to use, GNUTLS_DIG_SHA1 is a safe choice

flags: must be 0

This function will sign the certificate with the issuer’s private key, and will copy the issuer’s information into the certificate.

This must be the last step in a certificate generation since all the previously set parameters are now signed.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_x509_crt_set_pubkey

Function: int gnutls_x509_crt_set_pubkey (gnutls_x509_crt_t crt, gnutls_pubkey_t key)

crt: should contain a gnutls_x509_crt_t structure

key: holds a public key

This function will set the public parameters from the given public key to the request.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 2.12.0

Cryptographic API

The following functions are to be used for low-level cryptographic operations. Their prototypes lie in gnutls/crypto.h.

gnutls_cipher_add_auth

Function: int gnutls_cipher_add_auth (gnutls_cipher_hd_t handle, const void * text, size_t text_size)

handle: is a gnutls_cipher_hd_t structure.

text: the data to be authenticated

text_size: The length of the data

This function operates on authenticated encryption with associated data (AEAD) ciphers and authenticate the input data. This function can only be called once and before any encryption operations.

Returns: Zero or a negative error code on error.

Since: 3.0

gnutls_cipher_decrypt

Function: int gnutls_cipher_decrypt (gnutls_cipher_hd_t handle, void * ciphertext, size_t ciphertextlen)

handle: is a gnutls_cipher_hd_t structure.

ciphertext: the data to encrypt

ciphertextlen: The length of data to encrypt

This function will decrypt the given data using the algorithm specified by the context.

Returns: Zero or a negative error code on error.

Since: 2.10.0

gnutls_cipher_decrypt2

Function: int gnutls_cipher_decrypt2 (gnutls_cipher_hd_t handle, const void * ciphertext, size_t ciphertextlen, void * text, size_t textlen)

handle: is a gnutls_cipher_hd_t structure.

ciphertext: the data to encrypt

ciphertextlen: The length of data to encrypt

text: the decrypted data

textlen: The available length for decrypted data

This function will decrypt the given data using the algorithm specified by the context.

Returns: Zero or a negative error code on error.

Since: 2.12.0

gnutls_cipher_deinit

Function: void gnutls_cipher_deinit (gnutls_cipher_hd_t handle)

handle: is a gnutls_cipher_hd_t structure.

This function will deinitialize all resources occupied by the given encryption context.

Since: 2.10.0

gnutls_cipher_encrypt

Function: int gnutls_cipher_encrypt (gnutls_cipher_hd_t handle, void * text, size_t textlen)

handle: is a gnutls_cipher_hd_t structure.

text: the data to encrypt

textlen: The length of data to encrypt

This function will encrypt the given data using the algorithm specified by the context.

Returns: Zero or a negative error code on error.

Since: 2.10.0

gnutls_cipher_encrypt2

Function: int gnutls_cipher_encrypt2 (gnutls_cipher_hd_t handle, const void * text, size_t textlen, void * ciphertext, size_t ciphertextlen)

handle: is a gnutls_cipher_hd_t structure.

text: the data to encrypt

textlen: The length of data to encrypt

ciphertext: the encrypted data

ciphertextlen: The available length for encrypted data

This function will encrypt the given data using the algorithm specified by the context.

Returns: Zero or a negative error code on error.

Since: 2.12.0

gnutls_cipher_get_block_size

Function: int gnutls_cipher_get_block_size (gnutls_cipher_algorithm_t algorithm)

algorithm: is an encryption algorithm

Get block size for encryption algorithm.

Returns: block size for encryption algorithm.

Since: 2.10.0

gnutls_cipher_init

Function: int gnutls_cipher_init (gnutls_cipher_hd_t * handle, gnutls_cipher_algorithm_t cipher, const gnutls_datum_t * key, const gnutls_datum_t * iv)

handle: is a gnutls_cipher_hd_t structure.

cipher: the encryption algorithm to use

key: The key to be used for encryption

iv: The IV to use (if not applicable set NULL)

This function will initialize an context that can be used for encryption/decryption of data. This will effectively use the current crypto backend in use by gnutls or the cryptographic accelerator in use.

Returns: Zero or a negative error code on error.

Since: 2.10.0

gnutls_cipher_set_iv

Function: void gnutls_cipher_set_iv (gnutls_cipher_hd_t handle, void * iv, size_t ivlen)

handle: is a gnutls_cipher_hd_t structure.

iv: the IV to set

ivlen: The length of the IV

This function will set the IV to be used for the next encryption block.

Since: 3.0

gnutls_cipher_tag

Function: int gnutls_cipher_tag (gnutls_cipher_hd_t handle, void * tag, size_t tag_size)

handle: is a gnutls_cipher_hd_t structure.

tag: will hold the tag

tag_size: The length of the tag to return

This function operates on authenticated encryption with associated data (AEAD) ciphers and will return the output tag.

Returns: Zero or a negative error code on error.

Since: 3.0

gnutls_hash

Function: int gnutls_hash (gnutls_hash_hd_t handle, const void * text, size_t textlen)

handle: is a gnutls_cipher_hd_t structure.

text: the data to hash

textlen: The length of data to hash

This function will hash the given data using the algorithm specified by the context.

Returns: Zero or a negative error code on error.

Since: 2.10.0

gnutls_hash_deinit

Function: void gnutls_hash_deinit (gnutls_hash_hd_t handle, void * digest)

handle: is a gnutls_hash_hd_t structure.

digest: is the output value of the hash

This function will deinitialize all resources occupied by the given hash context.

Since: 2.10.0

gnutls_hash_fast

Function: int gnutls_hash_fast (gnutls_digest_algorithm_t algorithm, const void * text, size_t textlen, void * digest)

algorithm: the hash algorithm to use

text: the data to hash

textlen: The length of data to hash

digest: is the output value of the hash

This convenience function will hash the given data and return output on a single call.

Returns: Zero or a negative error code on error.

Since: 2.10.0

gnutls_hash_get_len

Function: int gnutls_hash_get_len (gnutls_digest_algorithm_t algorithm)

algorithm: the hash algorithm to use

This function will return the length of the output data of the given hash algorithm.

Returns: The length or zero on error.

Since: 2.10.0

gnutls_hash_init

Function: int gnutls_hash_init (gnutls_hash_hd_t * dig, gnutls_digest_algorithm_t algorithm)

dig: is a gnutls_hash_hd_t structure.

algorithm: the hash algorithm to use

This function will initialize an context that can be used to produce a Message Digest of data. This will effectively use the current crypto backend in use by gnutls or the cryptographic accelerator in use.

Returns: Zero or a negative error code on error.

Since: 2.10.0

gnutls_hash_output

Function: void gnutls_hash_output (gnutls_hash_hd_t handle, void * digest)

handle: is a gnutls_hash_hd_t structure.

digest: is the output value of the hash

This function will output the current hash value.

Since: 2.10.0

gnutls_hmac

Function: int gnutls_hmac (gnutls_hmac_hd_t handle, const void * text, size_t textlen)

handle: is a gnutls_cipher_hd_t structure.

text: the data to hash

textlen: The length of data to hash

This function will hash the given data using the algorithm specified by the context.

Returns: Zero or a negative error code on error.

Since: 2.10.0

gnutls_hmac_deinit

Function: void gnutls_hmac_deinit (gnutls_hmac_hd_t handle, void * digest)

handle: is a gnutls_hmac_hd_t structure.

digest: is the output value of the MAC

This function will deinitialize all resources occupied by the given hmac context.

Since: 2.10.0

gnutls_hmac_fast

Function: int gnutls_hmac_fast (gnutls_mac_algorithm_t algorithm, const void * key, size_t keylen, const void * text, size_t textlen, void * digest)

algorithm: the hash algorithm to use

key: the key to use

keylen: The length of the key

text: the data to hash

textlen: The length of data to hash

digest: is the output value of the hash

This convenience function will hash the given data and return output on a single call.

Returns: Zero or a negative error code on error.

Since: 2.10.0

gnutls_hmac_get_len

Function: int gnutls_hmac_get_len (gnutls_mac_algorithm_t algorithm)

algorithm: the hmac algorithm to use

This function will return the length of the output data of the given hmac algorithm.

Returns: The length or zero on error.

Since: 2.10.0

gnutls_hmac_init

Function: int gnutls_hmac_init (gnutls_hmac_hd_t * dig, gnutls_mac_algorithm_t algorithm, const void * key, size_t keylen)

dig: is a gnutls_hmac_hd_t structure.

algorithm: the HMAC algorithm to use

key: The key to be used for encryption

keylen: The length of the key

This function will initialize an context that can be used to produce a Message Authentication Code (MAC) of data. This will effectively use the current crypto backend in use by gnutls or the cryptographic accelerator in use.

Returns: Zero or a negative error code on error.

Since: 2.10.0

gnutls_hmac_output

Function: void gnutls_hmac_output (gnutls_hmac_hd_t handle, void * digest)

handle: is a gnutls_hmac_hd_t structure.

digest: is the output value of the MAC

This function will output the current MAC value.

Since: 2.10.0

gnutls_rnd

Function: int gnutls_rnd (gnutls_rnd_level_t level, void * data, size_t len)

level: a security level

data: place to store random bytes

len: The requested size

This function will generate random data and store it to output buffer.

Returns: Zero or a negative error code on error.

Since: 2.12.0

Compatibility API

The following functions are carried over from old GnuTLS released. They might be removed at a later version. Their prototypes lie in gnutls/compat.h.

gnutls_certificate_set_rsa_export_params

Function: void gnutls_certificate_set_rsa_export_params (gnutls_certificate_credentials_t                                           res, gnutls_rsa_params_t rsa_params)

res: is a gnutls_certificate_credentials_t structure

rsa_params: is a structure that holds temporary RSA parameters.

This function will set the temporary RSA parameters for a certificate server to use. These parameters will be used in RSA-EXPORT cipher suites.

gnutls_certificate_type_set_priority

Function: int gnutls_certificate_type_set_priority (gnutls_session_t session, const int * list)

session: is a gnutls_session_t structure.

list: is a 0 terminated list of gnutls_certificate_type_t elements.

Sets the priority on the certificate types supported by gnutls. Priority is higher for elements specified before others. After specifying the types you want, you must append a 0. Note that the certificate type priority is set on the client. The server does not use the cert type priority except for disabling types that were not specified.

Returns: GNUTLS_E_SUCCESS on success, or an error code.

gnutls_cipher_set_priority

Function: int gnutls_cipher_set_priority (gnutls_session_t session, const int * list)

session: is a gnutls_session_t structure.

list: is a 0 terminated list of gnutls_cipher_algorithm_t elements.

Sets the priority on the ciphers supported by gnutls. Priority is higher for elements specified before others. After specifying the ciphers you want, you must append a 0. Note that the priority is set on the client. The server does not use the algorithm’s priority except for disabling algorithms that were not specified.

Returns: GNUTLS_E_SUCCESS (0) on success, or a negative error code.

gnutls_compression_set_priority

Function: int gnutls_compression_set_priority (gnutls_session_t session, const int * list)

session: is a gnutls_session_t structure.

list: is a 0 terminated list of gnutls_compression_method_t elements.

Sets the priority on the compression algorithms supported by gnutls. Priority is higher for elements specified before others. After specifying the algorithms you want, you must append a 0. Note that the priority is set on the client. The server does not use the algorithm’s priority except for disabling algorithms that were not specified.

TLS 1.0 does not define any compression algorithms except NULL. Other compression algorithms are to be considered as gnutls extensions.

Returns: GNUTLS_E_SUCCESS on success, or an error code.

gnutls_kx_set_priority

Function: int gnutls_kx_set_priority (gnutls_session_t session, const int * list)

session: is a gnutls_session_t structure.

list: is a 0 terminated list of gnutls_kx_algorithm_t elements.

Sets the priority on the key exchange algorithms supported by gnutls. Priority is higher for elements specified before others. After specifying the algorithms you want, you must append a 0. Note that the priority is set on the client. The server does not use the algorithm’s priority except for disabling algorithms that were not specified.

Returns: GNUTLS_E_SUCCESS on success, or an error code.

gnutls_mac_set_priority

Function: int gnutls_mac_set_priority (gnutls_session_t session, const int * list)

session: is a gnutls_session_t structure.

list: is a 0 terminated list of gnutls_mac_algorithm_t elements.

Sets the priority on the mac algorithms supported by gnutls. Priority is higher for elements specified before others. After specifying the algorithms you want, you must append a 0. Note that the priority is set on the client. The server does not use the algorithm’s priority except for disabling algorithms that were not specified.

Returns: GNUTLS_E_SUCCESS on success, or an error code.

gnutls_openpgp_privkey_sign_hash

Function: int gnutls_openpgp_privkey_sign_hash (gnutls_openpgp_privkey_t key, const gnutls_datum_t * hash, gnutls_datum_t * signature)

key: Holds the key

hash: holds the data to be signed

signature: will contain newly allocated signature

This function will sign the given hash using the private key. You should use gnutls_openpgp_privkey_set_preferred_key_id() before calling this function to set the subkey to use.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Deprecated: Use gnutls_privkey_sign_hash() instead.

gnutls_protocol_set_priority

Function: int gnutls_protocol_set_priority (gnutls_session_t session, const int * list)

session: is a gnutls_session_t structure.

list: is a 0 terminated list of gnutls_protocol_t elements.

Sets the priority on the protocol versions supported by gnutls. This function actually enables or disables protocols. Newer protocol versions always have highest priority.

Returns: GNUTLS_E_SUCCESS on success, or an error code.

gnutls_rsa_export_get_modulus_bits

Function: int gnutls_rsa_export_get_modulus_bits (gnutls_session_t session)

session: is a gnutls session

Get the export RSA parameter’s modulus size.

Returns: The bits used in the last RSA-EXPORT key exchange with the peer, or a negative error code in case of error.

gnutls_rsa_export_get_pubkey

Function: int gnutls_rsa_export_get_pubkey (gnutls_session_t session, gnutls_datum_t * exponent, gnutls_datum_t * modulus)

session: is a gnutls session

exponent: will hold the exponent.

modulus: will hold the modulus.

This function will return the peer’s public key exponent and modulus used in the last RSA-EXPORT authentication. The output parameters must be freed with gnutls_free() .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise an error code is returned.

gnutls_rsa_params_cpy

Function: int gnutls_rsa_params_cpy (gnutls_rsa_params_t dst, gnutls_rsa_params_t src)

dst: Is the destination structure, which should be initialized.

src: Is the source structure

This function will copy the RSA parameters structure from source to destination.

Returns: GNUTLS_E_SUCCESS on success, or an negative error code.

gnutls_rsa_params_deinit

Function: void gnutls_rsa_params_deinit (gnutls_rsa_params_t rsa_params)

rsa_params: Is a structure that holds the parameters

This function will deinitialize the RSA parameters structure.

gnutls_rsa_params_export_pkcs1

Function: int gnutls_rsa_params_export_pkcs1 (gnutls_rsa_params_t params, gnutls_x509_crt_fmt_t format, unsigned char * params_data, size_t * params_data_size)

params: Holds the RSA parameters

format: the format of output params. One of PEM or DER.

params_data: will contain a PKCS1 RSAPublicKey structure PEM or DER encoded

params_data_size: holds the size of params_data (and will be replaced by the actual size of parameters)

This function will export the given RSA parameters to a PKCS1 RSAPublicKey structure. If the buffer provided is not long enough to hold the output, then GNUTLS_E_SHORT_MEMORY_BUFFER will be returned.

If the structure is PEM encoded, it will have a header of "BEGIN RSA PRIVATE KEY".

Returns: GNUTLS_E_SUCCESS on success, or an negative error code.

gnutls_rsa_params_export_raw

Function: int gnutls_rsa_params_export_raw (gnutls_rsa_params_t rsa, gnutls_datum_t * m, gnutls_datum_t * e, gnutls_datum_t * d, gnutls_datum_t * p, gnutls_datum_t * q, gnutls_datum_t * u, unsigned int * bits)

rsa: a structure that holds the rsa parameters

m: will hold the modulus

e: will hold the public exponent

d: will hold the private exponent

p: will hold the first prime (p)

q: will hold the second prime (q)

u: will hold the coefficient

bits: if non null will hold the prime’s number of bits

This function will export the RSA parameters found in the given structure. The new parameters will be allocated using gnutls_malloc() and will be stored in the appropriate datum.

Returns: GNUTLS_E_SUCCESS on success, or an negative error code.

gnutls_rsa_params_generate2

Function: int gnutls_rsa_params_generate2 (gnutls_rsa_params_t params, unsigned int bits)

params: The structure where the parameters will be stored

bits: is the prime’s number of bits

This function will generate new temporary RSA parameters for use in RSA-EXPORT ciphersuites. This function is normally slow.

Note that if the parameters are to be used in export cipher suites the bits value should be 512 or less. Also note that the generation of new RSA parameters is only useful to servers. Clients use the parameters sent by the server, thus it’s no use calling this in client side.

Returns: GNUTLS_E_SUCCESS on success, or an negative error code.

gnutls_rsa_params_import_pkcs1

Function: int gnutls_rsa_params_import_pkcs1 (gnutls_rsa_params_t params, const gnutls_datum_t * pkcs1_params, gnutls_x509_crt_fmt_t format)

params: A structure where the parameters will be copied to

pkcs1_params: should contain a PKCS1 RSAPublicKey structure PEM or DER encoded

format: the format of params. PEM or DER.

This function will extract the RSAPublicKey found in a PKCS1 formatted structure.

If the structure is PEM encoded, it should have a header of "BEGIN RSA PRIVATE KEY".

Returns: GNUTLS_E_SUCCESS on success, or an negative error code.

gnutls_rsa_params_import_raw

Function: int gnutls_rsa_params_import_raw (gnutls_rsa_params_t rsa_params, const gnutls_datum_t * m, const gnutls_datum_t * e, const gnutls_datum_t * d, const gnutls_datum_t * p, const gnutls_datum_t * q, const gnutls_datum_t * u)

rsa_params: Is a structure will hold the parameters

m: holds the modulus

e: holds the public exponent

d: holds the private exponent

p: holds the first prime (p)

q: holds the second prime (q)

u: holds the coefficient

This function will replace the parameters in the given structure. The new parameters should be stored in the appropriate gnutls_datum.

Returns: GNUTLS_E_SUCCESS on success, or an negative error code.

gnutls_rsa_params_init

Function: int gnutls_rsa_params_init (gnutls_rsa_params_t * rsa_params)

rsa_params: Is a structure that will hold the parameters

This function will initialize the temporary RSA parameters structure.

Returns: GNUTLS_E_SUCCESS on success, or an negative error code.

gnutls_set_default_export_priority

Function: int gnutls_set_default_export_priority (gnutls_session_t session)

session: is a gnutls_session_t structure.

Sets some default priority on the ciphers, key exchange methods, macs and compression methods. This function also includes weak algorithms.

This is the same as calling:

gnutls_priority_set_direct (session, "EXPORT", NULL);

This function is kept around for backwards compatibility, but because of its wide use it is still fully supported. If you wish to allow users to provide a string that specify which ciphers to use (which is recommended), you should use gnutls_priority_set_direct() or gnutls_priority_set() instead.

Returns: GNUTLS_E_SUCCESS on success, or an error code.

gnutls_sign_callback_get

Function: gnutls_sign_func gnutls_sign_callback_get (gnutls_session_t session, void ** userdata)

session: is a gnutls session

userdata: if non-NULL , will be set to abstract callback pointer.

Retrieve the callback function, and its userdata pointer.

Returns: The function pointer set by gnutls_sign_callback_set() , or if not set, NULL .

Deprecated: Use the PKCS 11 interfaces instead.

gnutls_sign_callback_set

Function: void gnutls_sign_callback_set (gnutls_session_t session, gnutls_sign_func sign_func, void * userdata)

session: is a gnutls session

sign_func: function pointer to application’s sign callback.

userdata: void pointer that will be passed to sign callback.

Set the callback function. The function must have this prototype:

typedef int (*gnutls_sign_func) (gnutls_session_t session, void *userdata, gnutls_certificate_type_t cert_type, const gnutls_datum_t * cert, const gnutls_datum_t * hash, gnutls_datum_t * signature);

The userdata parameter is passed to the sign_func verbatim, and can be used to store application-specific data needed in the callback function. See also gnutls_sign_callback_get() .

Deprecated: Use the PKCS 11 or gnutls_privkey_t interfacess like gnutls_privkey_import_ext() instead.

gnutls_x509_crl_sign

Function: int gnutls_x509_crl_sign (gnutls_x509_crl_t crl, gnutls_x509_crt_t issuer, gnutls_x509_privkey_t issuer_key)

crl: should contain a gnutls_x509_crl_t structure

issuer: is the certificate of the certificate issuer

issuer_key: holds the issuer’s private key

This function is the same a gnutls_x509_crl_sign2() with no flags, and SHA1 as the hash algorithm.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Deprecated: Use gnutls_x509_crl_privkey_sign() .

gnutls_x509_crq_sign

Function: int gnutls_x509_crq_sign (gnutls_x509_crq_t crq, gnutls_x509_privkey_t key)

crq: should contain a gnutls_x509_crq_t structure

key: holds a private key

This function is the same a gnutls_x509_crq_sign2() with no flags, and SHA1 as the hash algorithm.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Deprecated: Use gnutls_x509_crq_privkey_sign() instead.

gnutls_x509_crt_get_preferred_hash_algorithm

Function: int gnutls_x509_crt_get_preferred_hash_algorithm (gnutls_x509_crt_t crt, gnutls_digest_algorithm_t *                                               hash, unsigned int * mand)

crt: Holds the certificate

hash: The result of the call with the hash algorithm used for signature

mand: If non (0) it means that the algorithm MUST use this hash. May be NULL.

This function will read the certifcate and return the appropriate digest algorithm to use for signing with this certificate. Some certificates (i.e. DSA might not be able to sign without the preferred algorithm).

Deprecated: Please use gnutls_pubkey_get_preferred_hash_algorithm() .

Returns: the 0 if the hash algorithm is found. A negative error code is returned on error.

Since: 2.12.0

gnutls_x509_crt_get_verify_algorithm

Function: int gnutls_x509_crt_get_verify_algorithm (gnutls_x509_crt_t crt, const gnutls_datum_t * signature, gnutls_digest_algorithm_t * hash)

crt: Holds the certificate

signature: contains the signature

hash: The result of the call with the hash algorithm used for signature

This function will read the certifcate and the signed data to determine the hash algorithm used to generate the signature.

Deprecated: Use gnutls_pubkey_get_verify_algorithm() instead.

Returns: the 0 if the hash algorithm is found. A negative error code is returned on error.

Since: 2.8.0

gnutls_x509_crt_verify_data

Function: int gnutls_x509_crt_verify_data (gnutls_x509_crt_t crt, unsigned int flags, const gnutls_datum_t * data, const gnutls_datum_t * signature)

crt: Holds the certificate

flags: should be 0 for now

data: holds the data to be signed

signature: contains the signature

This function will verify the given signed data, using the parameters from the certificate.

Deprecated. Please use gnutls_pubkey_verify_data() .

Returns: In case of a verification failure GNUTLS_E_PK_SIG_VERIFY_FAILED is returned, and zero or positive code on success.

gnutls_x509_crt_verify_hash

Function: int gnutls_x509_crt_verify_hash (gnutls_x509_crt_t crt, unsigned int flags, const gnutls_datum_t * hash, const gnutls_datum_t * signature)

crt: Holds the certificate

flags: should be 0 for now

hash: holds the hash digest to be verified

signature: contains the signature

This function will verify the given signed digest, using the parameters from the certificate.

Deprecated. Please use gnutls_pubkey_verify_data() .

Returns: In case of a verification failure GNUTLS_E_PK_SIG_VERIFY_FAILED is returned, and zero or positive code on success.

gnutls_x509_privkey_sign_data

Function: int gnutls_x509_privkey_sign_data (gnutls_x509_privkey_t key, gnutls_digest_algorithm_t digest, unsigned int flags, const gnutls_datum_t * data, void * signature, size_t * signature_size)

key: Holds the key

digest: should be MD5 or SHA1

flags: should be 0 for now

data: holds the data to be signed

signature: will contain the signature

signature_size: holds the size of signature (and will be replaced by the new size)

This function will sign the given data using a signature algorithm supported by the private key. Signature algorithms are always used together with a hash functions. Different hash functions may be used for the RSA algorithm, but only SHA-1 for the DSA keys.

If the buffer provided is not long enough to hold the output, then * signature_size is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will be returned.

Use gnutls_x509_crt_get_preferred_hash_algorithm() to determine the hash algorithm.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Deprecated: Use gnutls_privkey_sign_data() .

gnutls_x509_privkey_sign_hash

Function: int gnutls_x509_privkey_sign_hash (gnutls_x509_privkey_t key, const gnutls_datum_t * hash, gnutls_datum_t * signature)

key: Holds the key

hash: holds the data to be signed

signature: will contain newly allocated signature

This function will sign the given hash using the private key. Do not use this function directly unless you know what it is. Typical signing requires the data to be hashed and stored in special formats (e.g. BER Digest-Info for RSA).

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Deprecated in: 2.12.0

Appendix E. Copying Information

GNU Free Documentation License

Version 1.3, 3 November 2008

Copyright © 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
http://fsf.org/

Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.

PREAMBLE

The purpose of this License is to make a manual, textbook, or other functional and useful document free in the sense of freedom: to assure everyone the effective freedom to copy and redistribute it, with or without modifying it, either commercially or noncommercially. Secondarily, this License preserves for the author and publisher a way to get credit for their work, while not being considered responsible for modifications made by others.

This License is a kind of “copyleft”, which means that derivative works of the document must themselves be free in the same sense. It complements the GNU General Public License, which is a copyleft license designed for free software.

We have designed this License in order to use it for manuals for free software, because free software needs free documentation: a free program should come with manuals providing the same freedoms that the software does. But this License is not limited to software manuals; it can be used for any textual work, regardless of subject matter or whether it is published as a printed book. We recommend this License principally for works whose purpose is instruction or reference.

APPLICABILITY AND DEFINITIONS

This License applies to any manual or other work, in any medium, that contains a notice placed by the copyright holder saying it can be distributed under the terms of this License. Such a notice grants a world-wide, royalty-free license, unlimited in duration, to use that work under the conditions stated herein. The “Document”, below, refers to any such manual or work. Any member of the public is a licensee, and is addressed as “you”. You accept the license if you copy, modify or distribute the work in a way requiring permission under copyright law.

A “Modified Version” of the Document means any work containing the Document or a portion of it, either copied verbatim, or with modifications and/or translated into another language.

A “Secondary Section” is a named appendix or a front-matter section of the Document that deals exclusively with the relationship of the publishers or authors of the Document to the Document’s overall subject (or to related matters) and contains nothing that could fall directly within that overall subject. (Thus, if the Document is in part a textbook of mathematics, a Secondary Section may not explain any mathematics.) The relationship could be a matter of historical connection with the subject or with related matters, or of legal, commercial, philosophical, ethical or political position regarding them.

The “Invariant Sections” are certain Secondary Sections whose titles are designated, as being those of Invariant Sections, in the notice that says that the Document is released under this License. If a section does not fit the above definition of Secondary then it is not allowed to be designated as Invariant. The Document may contain zero Invariant Sections. If the Document does not identify any Invariant Sections then there are none.

The “Cover Texts” are certain short passages of text that are listed, as Front-Cover Texts or Back-Cover Texts, in the notice that says that the Document is released under this License. A Front-Cover Text may be at most 5 words, and a Back-Cover Text may be at most 25 words.

A “Transparent” copy of the Document means a machine-readable copy, represented in a format whose specification is available to the general public, that is suitable for revising the document straightforwardly with generic text editors or (for images composed of pixels) generic paint programs or (for drawings) some widely available drawing editor, and that is suitable for input to text formatters or for automatic translation to a variety of formats suitable for input to text formatters. A copy made in an otherwise Transparent file format whose markup, or absence of markup, has been arranged to thwart or discourage subsequent modification by readers is not Transparent. An image format is not Transparent if used for any substantial amount of text. A copy that is not “Transparent” is called “Opaque”.

Examples of suitable formats for Transparent copies include plain ASCII without markup, Texinfo input format, LaTeX input format, SGML or XML using a publicly available DTD, and standard-conforming simple HTML, PostScript or PDF designed for human modification. Examples of transparent image formats include PNG, XCF and JPG. Opaque formats include proprietary formats that can be read and edited only by proprietary word processors, SGML or XML for which the DTD and/or processing tools are not generally available, and the machine-generated HTML, PostScript or PDF produced by some word processors for output purposes only.

The “Title Page” means, for a printed book, the title page itself, plus such following pages as are needed to hold, legibly, the material this License requires to appear in the title page. For works in formats which do not have any title page as such, “Title Page” means the text near the most prominent appearance of the work’s title, preceding the beginning of the body of the text.

The “publisher” means any person or entity that distributes copies of the Document to the public.

A section “Entitled XYZ” means a named subunit of the Document whose title either is precisely XYZ or contains XYZ in parentheses following text that translates XYZ in another language. (Here XYZ stands for a specific section name mentioned below, such as “Acknowledgements”, “Dedications”, “Endorsements”, or “History”.) To “Preserve the Title” of such a section when you modify the Document means that it remains a section “Entitled XYZ” according to this definition.

The Document may include Warranty Disclaimers next to the notice which states that this License applies to the Document. These Warranty Disclaimers are considered to be included by reference in this License, but only as regards disclaiming warranties: any other implication that these Warranty Disclaimers may have is void and has no effect on the meaning of this License.

VERBATIM COPYING

You may copy and distribute the Document in any medium, either commercially or noncommercially, provided that this License, the copyright notices, and the license notice saying this License applies to the Document are reproduced in all copies, and that you add no other conditions whatsoever to those of this License. You may not use technical measures to obstruct or control the reading or further copying of the copies you make or distribute. However, you may accept compensation in exchange for copies. If you distribute a large enough number of copies you must also follow the conditions in section 3.

You may also lend copies, under the same conditions stated above, and you may publicly display copies.

COPYING IN QUANTITY

If you publish printed copies (or copies in media that commonly have printed covers) of the Document, numbering more than 100, and the Document’s license notice requires Cover Texts, you must enclose the copies in covers that carry, clearly and legibly, all these Cover Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on the back cover. Both covers must also clearly and legibly identify you as the publisher of these copies. The front cover must present the full title with all words of the title equally prominent and visible. You may add other material on the covers in addition. Copying with changes limited to the covers, as long as they preserve the title of the Document and satisfy these conditions, can be treated as verbatim copying in other respects.

If the required texts for either cover are too voluminous to fit legibly, you should put the first ones listed (as many as fit reasonably) on the actual cover, and continue the rest onto adjacent pages.

If you publish or distribute Opaque copies of the Document numbering more than 100, you must either include a machine-readable Transparent copy along with each Opaque copy, or state in or with each Opaque copy a computer-network location from which the general network-using public has access to download using public-standard network protocols a complete Transparent copy of the Document, free of added material. If you use the latter option, you must take reasonably prudent steps, when you begin distribution of Opaque copies in quantity, to ensure that this Transparent copy will remain thus accessible at the stated location until at least one year after the last time you distribute an Opaque copy (directly or through your agents or retailers) of that edition to the public.

It is requested, but not required, that you contact the authors of the Document well before redistributing any large number of copies, to give them a chance to provide you with an updated version of the Document.

MODIFICATIONS

You may copy and distribute a Modified Version of the Document under the conditions of sections 2 and 3 above, provided that you release the Modified Version under precisely this License, with the Modified Version filling the role of the Document, thus licensing distribution and modification of the Modified Version to whoever possesses a copy of it. In addition, you must do these things in the Modified Version:

Use in the Title Page (and on the covers, if any) a title distinct from that of the Document, and from those of previous versions (which should, if there were any, be listed in the History section of the Document). You may use the same title as a previous version if the original publisher of that version gives permission.

List on the Title Page, as authors, one or more persons or entities responsible for authorship of the modifications in the Modified Version, together with at least five of the principal authors of the Document (all of its principal authors, if it has fewer than five), unless they release you from this requirement.

State on the Title page the name of the publisher of the Modified Version, as the publisher.

Preserve all the copyright notices of the Document.

Add an appropriate copyright notice for your modifications adjacent to the other copyright notices.

Include, immediately after the copyright notices, a license notice giving the public permission to use the Modified Version under the terms of this License, in the form shown in the Addendum below.

Preserve in that license notice the full lists of Invariant Sections and required Cover Texts given in the Document’s license notice.

Include an unaltered copy of this License.

Preserve the section Entitled “History”, Preserve its Title, and add to it an item stating at least the title, year, new authors, and publisher of the Modified Version as given on the Title Page. If there is no section Entitled “History” in the Document, create one stating the title, year, authors, and publisher of the Document as given on its Title Page, then add an item describing the Modified Version as stated in the previous sentence.

Preserve the network location, if any, given in the Document for public access to a Transparent copy of the Document, and likewise the network locations given in the Document for previous versions it was based on. These may be placed in the “History” section. You may omit a network location for a work that was published at least four years before the Document itself, or if the original publisher of the version it refers to gives permission.

For any section Entitled “Acknowledgements” or “Dedications”, Preserve the Title of the section, and preserve in the section all the substance and tone of each of the contributor acknowledgements and/or dedications given therein.

Preserve all the Invariant Sections of the Document, unaltered in their text and in their titles. Section numbers or the equivalent are not considered part of the section titles.

Delete any section Entitled “Endorsements”. Such a section may not be included in the Modified Version.

Do not retitle any existing section to be Entitled “Endorsements” or to conflict in title with any Invariant Section.

Preserve any Warranty Disclaimers.

If the Modified Version includes new front-matter sections or appendices that qualify as Secondary Sections and contain no material copied from the Document, you may at your option designate some or all of these sections as invariant. To do this, add their titles to the list of Invariant Sections in the Modified Version’s license notice. These titles must be distinct from any other section titles.

You may add a section Entitled “Endorsements”, provided it contains nothing but endorsements of your Modified Version by various parties—for example, statements of peer review or that the text has been approved by an organization as the authoritative definition of a standard.

You may add a passage of up to five words as a Front-Cover Text, and a passage of up to 25 words as a Back-Cover Text, to the end of the list of Cover Texts in the Modified Version. Only one passage of Front-Cover Text and one of Back-Cover Text may be added by (or through arrangements made by) any one entity. If the Document already includes a cover text for the same cover, previously added by you or by arrangement made by the same entity you are acting on behalf of, you may not add another; but you may replace the old one, on explicit permission from the previous publisher that added the old one.

The author(s) and publisher(s) of the Document do not by this License give permission to use their names for publicity for or to assert or imply endorsement of any Modified Version.

COMBINING DOCUMENTS

You may combine the Document with other documents released under this License, under the terms defined in section 4 above for modified versions, provided that you include in the combination all of the Invariant Sections of all of the original documents, unmodified, and list them all as Invariant Sections of your combined work in its license notice, and that you preserve all their Warranty Disclaimers.

The combined work need only contain one copy of this License, and multiple identical Invariant Sections may be replaced with a single copy. If there are multiple Invariant Sections with the same name but different contents, make the title of each such section unique by adding at the end of it, in parentheses, the name of the original author or publisher of that section if known, or else a unique number. Make the same adjustment to the section titles in the list of Invariant Sections in the license notice of the combined work.

In the combination, you must combine any sections Entitled “History” in the various original documents, forming one section Entitled “History”; likewise combine any sections Entitled “Acknowledgements”, and any sections Entitled “Dedications”. You must delete all sections Entitled “Endorsements.”

COLLECTIONS OF DOCUMENTS

You may make a collection consisting of the Document and other documents released under this License, and replace the individual copies of this License in the various documents with a single copy that is included in the collection, provided that you follow the rules of this License for verbatim copying of each of the documents in all other respects.

You may extract a single document from such a collection, and distribute it individually under this License, provided you insert a copy of this License into the extracted document, and follow this License in all other respects regarding verbatim copying of that document.

AGGREGATION WITH INDEPENDENT WORKS

A compilation of the Document or its derivatives with other separate and independent documents or works, in or on a volume of a storage or distribution medium, is called an “aggregate” if the copyright resulting from the compilation is not used to limit the legal rights of the compilation’s users beyond what the individual works permit. When the Document is included in an aggregate, this License does not apply to the other works in the aggregate which are not themselves derivative works of the Document.

If the Cover Text requirement of section 3 is applicable to these copies of the Document, then if the Document is less than one half of the entire aggregate, the Document’s Cover Texts may be placed on covers that bracket the Document within the aggregate, or the electronic equivalent of covers if the Document is in electronic form. Otherwise they must appear on printed covers that bracket the whole aggregate.

TRANSLATION

Translation is considered a kind of modification, so you may distribute translations of the Document under the terms of section 4. Replacing Invariant Sections with translations requires special permission from their copyright holders, but you may include translations of some or all Invariant Sections in addition to the original versions of these Invariant Sections. You may include a translation of this License, and all the license notices in the Document, and any Warranty Disclaimers, provided that you also include the original English version of this License and the original versions of those notices and disclaimers. In case of a disagreement between the translation and the original version of this License or a notice or disclaimer, the original version will prevail.

If a section in the Document is Entitled “Acknowledgements”, “Dedications”, or “History”, the requirement (section 4) to Preserve its Title (section 1) will typically require changing the actual title.

TERMINATION

You may not copy, modify, sublicense, or distribute the Document except as expressly provided under this License. Any attempt otherwise to copy, modify, sublicense, or distribute it is void, and will automatically terminate your rights under this License.

However, if you cease all violation of this License, then your license from a particular copyright holder is reinstated (a) provisionally, unless and until the copyright holder explicitly and finally terminates your license, and (b) permanently, if the copyright holder fails to notify you of the violation by some reasonable means prior to 60 days after the cessation.

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Chapter . Bibliography

[CBCATT]

Bodo Moeller, "Security of CBC Ciphersuites in SSL/TLS: Problems and Countermeasures", 2002, available from http://www.openssl.org/~bodo/tls-cbc.txt.

[GPGH]

Mike Ashley, "The GNU Privacy Handbook", 2002, available from http://www.gnupg.org/gph/en/manual.pdf.

[GUTPKI]

Peter Gutmann, "Everything you never wanted to know about PKI but were forced to find out", Available from http://www.cs.auckland.ac.nz/~pgut001/.

[KEYPIN]

Chris Evans and Chris Palmer, "Public Key Pinning Extension for HTTP", Available from http://tools.ietf.org/html/draft-ietf-websec-key-pinning-01.

[NISTSP80057]

NIST Special Publication 800-57, "Recommendation for Key Management - Part 1: General (Revised)", March 2007, available from http://csrc.nist.gov/publications/nistpubs/800-57/sp800-57-Part1-revised2_Mar08-2007.pdf.

[RFC2246]

Tim Dierks and Christopher Allen, "The TLS Protocol Version 1.0", January 1999, Available from http://www.ietf.org/rfc/rfc2246.txt.

[RFC4680]

S. Santesson, "TLS Handshake Message for Supplemental Data", September 2006, Available from http://www.ietf.org/rfc/rfc4680.txt.

[RFC4514]

Kurt D. Zeilenga, "Lightweight Directory Access Protocol (LDAP): String Representation of Distinguished Names", June 2006, Available from http://www.ietf.org/rfc/rfc4513.txt.

[RFC4346]

Tim Dierks and Eric Rescorla, "The TLS Protocol Version 1.1", Match 2006, Available from http://www.ietf.org/rfc/rfc4346.txt.

[RFC4347]

Eric Rescorla and Nagendra Modadugu, "Datagram Transport Layer Security", April 2006, Available from http://www.ietf.org/rfc/rfc4347.txt.

[RFC5246]

Tim Dierks and Eric Rescorla, "The TLS Protocol Version 1.2", August 2008, Available from http://www.ietf.org/rfc/rfc5246.txt.

[RFC2440]

Jon Callas, Lutz Donnerhacke, Hal Finney and Rodney Thayer, "OpenPGP Message Format", November 1998, Available from http://www.ietf.org/rfc/rfc2440.txt.

[RFC4880]

Jon Callas, Lutz Donnerhacke, Hal Finney, David Shaw and Rodney Thayer, "OpenPGP Message Format", November 2007, Available from http://www.ietf.org/rfc/rfc4880.txt.

[RFC4211]

J. Schaad, "Internet X.509 Public Key Infrastructure Certificate Request Message Format (CRMF)", September 2005, Available from http://www.ietf.org/rfc/rfc4211.txt.

[RFC2817]

Rohit Khare and Scott Lawrence, "Upgrading to TLS Within HTTP/1.1", May 2000, Available from http://www.ietf.org/rfc/rfc2817.txt

[RFC2818]

Eric Rescorla, "HTTP Over TLS", May 2000, Available from http://www.ietf/rfc/rfc2818.txt.

[RFC2945]

Tom Wu, "The SRP Authentication and Key Exchange System", September 2000, Available from http://www.ietf.org/rfc/rfc2945.txt.

[RFC2986]

Magnus Nystrom and Burt Kaliski, "PKCS 10 v1.7: Certification Request Syntax Specification", November 2000, Available from http://www.ietf.org/rfc/rfc2986.txt.

[PKIX]

D. Cooper, S. Santesson, S. Farrel, S. Boeyen, R. Housley, W. Polk, "Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile", May 2008, available from http://www.ietf.org/rfc/rfc5280.txt.

[RFC3749]

Scott Hollenbeck, "Transport Layer Security Protocol Compression Methods", May 2004, available from http://www.ietf.org/rfc/rfc3749.txt.

[RFC3820]

Steven Tuecke, Von Welch, Doug Engert, Laura Pearlman, and Mary Thompson, "Internet X.509 Public Key Infrastructure (PKI) Proxy Certificate Profile", June 2004, available from http://www.ietf.org/rfc/rfc3820.

[RFC5746]

E. Rescorla, M. Ray, S. Dispensa, and N. Oskov, "Transport Layer Security (TLS) Renegotiation Indication Extension", February 2010, available from http://www.ietf.org/rfc/rfc5746.

[TLSTKT]

Joseph Salowey, Hao Zhou, Pasi Eronen, Hannes Tschofenig, "Transport Layer Security (TLS) Session Resumption without Server-Side State", January 2008, available from http://www.ietf.org/rfc/rfc5077.

[PKCS12]

RSA Laboratories, "PKCS 12 v1.0: Personal Information Exchange Syntax", June 1999, Available from http://www.rsa.com.

[PKCS11]

RSA Laboratories, "PKCS #11 Base Functionality v2.30: Cryptoki â Draft 4", July 2009, Available from http://www.rsa.com.

[RESCORLA]

Eric Rescorla, "SSL and TLS: Designing and Building Secure Systems", 2001

[SELKEY]

Arjen Lenstra and Eric Verheul, "Selecting Cryptographic Key Sizes", 2003, available from http://www.win.tue.nl/~klenstra/key.pdf.

[SSL3]

Alan Freier, Philip Karlton and Paul Kocher, "The Secure Sockets Layer (SSL) Protocol Version 3.0", August 2011, Available from http://www.ietf.org/rfc/rfc6101.txt.

[STEVENS]

Richard Stevens, "UNIX Network Programming, Volume 1", Prentice Hall PTR, January 1998

[TLSEXT]

Simon Blake-Wilson, Magnus Nystrom, David Hopwood, Jan Mikkelsen and Tim Wright, "Transport Layer Security (TLS) Extensions", June 2003, Available from http://www.ietf.org/rfc/rfc3546.txt.

[TLSPGP]

Nikos Mavrogiannopoulos, "Using OpenPGP keys for TLS authentication", January 2011. Available from http://www.ietf.org/rfc/rfc6091.txt.

[TLSSRP]

David Taylor, Trevor Perrin, Tom Wu and Nikos Mavrogiannopoulos, "Using SRP for TLS Authentication", November 2007. Available from http://www.ietf.org/rfc/rfc5054.txt.

[TLSPSK]

Pasi Eronen and Hannes Tschofenig, "Pre-shared key Ciphersuites for TLS", December 2005, Available from http://www.ietf.org/rfc/rfc4279.txt.

[TOMSRP]

Tom Wu, "The Stanford SRP Authentication Project", Available at http://srp.stanford.edu/.

[WEGER]

Arjen Lenstra and Xiaoyun Wang and Benne de Weger, "Colliding X.509 Certificates", Cryptology ePrint Archive, Report 2005/067, Available at http://eprint.iacr.org/.

[ECRYPT]

European Network of Excellence in Cryptology II, "ECRYPT II Yearly Report on Algorithms and Keysizes (2009-2010)", Available at http://www.ecrypt.eu.org/documents/D.SPA.13.pdf.

[RFC5056]

N. Williams, "On the Use of Channel Bindings to Secure Channels", November 2007, available from http://www.ietf.org/rfc/rfc5056.

[RFC5929]

J. Altman, N. Williams, L. Zhu, "Channel Bindings for TLS", July 2010, available from http://www.ietf.org/rfc/rfc5929.

[PKCS11URI]

J. Pechanec, D. Moffat, "The PKCS#11 URI Scheme", August 2011, Work in progress, available from http://tools.ietf.org/html/draft-pechanec-pkcs11uri-05.

[ANDERSON]

R. J. Anderson, "Security Engineering: A Guide to Building Dependable Distributed Systems", John Wiley \& Sons, Inc., 2001.

[RFC4821]

M. Mathis, J. Heffner, "Packetization Layer Path MTU Discovery", March 2007, available from http://www.ietf.org/rfc/rfc4821.txt.

[RFC2560]

M. Myers et al, "X.509 Internet Public Key Infrastructure Online Certificate Status Protocol - OCSP", June 1999, Available from http://www.ietf.org/rfc/rfc2560.txt.

[RIVESTCRL]

R. L. Rivest, "Can We Eliminate Certificate Revocation Lists?", Proceedings of Financial Cryptography ’98; Springer Lecture Notes in Computer Science No. 1465 (Rafael Hirschfeld, ed.), February 1998), pages 178–183, available from http://people.csail.mit.edu/rivest/Rivest-CanWeEliminateCertificateRevocationLists.pdf.

Chapter . Function and Data Index

Index

A

abstract types, Abstract key types

alert protocol, The TLS alert protocol

anonymous authentication, Anonymous authentication

API reference, API reference

B

bad_record_mac, On record padding

C

callback functions, Callback functions

certificate authentication, Certificate authentication, More on certificate authentication

certificate requests, PKCS #10 certificate requests

certificate revocation lists, PKIX certificate revocation lists

certificate status, OCSP certificate status checking

certtool, Invoking certtool

certtool usage, Invoking certtool

certtool-bits, Invoking certtool

certtool-certificate-info, Invoking certtool

certtool-certificate-pubkey, Invoking certtool

certtool-crl-info, Invoking certtool

certtool-crq-info, Invoking certtool

certtool-debug, Invoking certtool

certtool-dh-info, Invoking certtool

certtool-disable-quick-random, Invoking certtool

certtool-dsa, Invoking certtool

certtool-ecc, Invoking certtool

certtool-generate-certificate, Invoking certtool

certtool-generate-crl, Invoking certtool

certtool-generate-dh-params, Invoking certtool

certtool-generate-privkey, Invoking certtool

certtool-generate-proxy, Invoking certtool

certtool-generate-request, Invoking certtool

certtool-generate-self-signed, Invoking certtool

certtool-get-dh-params, Invoking certtool

certtool-hash, Invoking certtool

certtool-inder, Invoking certtool

certtool-infile, Invoking certtool

certtool-inraw, Invoking certtool

certtool-key-info, Invoking certtool

certtool-load-ca-certificate, Invoking certtool

certtool-load-ca-privkey, Invoking certtool

certtool-load-certificate, Invoking certtool

certtool-load-privkey, Invoking certtool

certtool-load-pubkey, Invoking certtool

certtool-load-request, Invoking certtool

certtool-no-crq-extensions, Invoking certtool

certtool-outder, Invoking certtool

certtool-outfile, Invoking certtool

certtool-outraw, Invoking certtool

certtool-p12-info, Invoking certtool

certtool-p7-info, Invoking certtool

certtool-password, Invoking certtool

certtool-pgp-certificate-info, Invoking certtool

certtool-pgp-key-info, Invoking certtool

certtool-pgp-ring-info, Invoking certtool

certtool-pkcs-cipher, Invoking certtool

certtool-pkcs8, Invoking certtool

certtool-pubkey-info, Invoking certtool

certtool-rsa, Invoking certtool

certtool-sec-param, Invoking certtool

certtool-smime-to-p7, Invoking certtool

certtool-template, Invoking certtool

certtool-to-p12, Invoking certtool

certtool-to-p8, Invoking certtool

certtool-update-certificate, Invoking certtool

certtool-v1, Invoking certtool

certtool-verify, Invoking certtool

certtool-verify-chain, Invoking certtool

certtool-verify-crl, Invoking certtool

channel bindings, Channel bindings

ciphersuites, Supported Ciphersuites

client certificate authentication, Client authentication

compression algorithms, Compression algorithms used in the record layer

contributing, Contributing

CRL, PKIX certificate revocation lists

D

digital signatures, Digital signatures

download, Downloading and installing

E

Encrypted keys, Managing encrypted keys

error codes, Error Codes and Descriptions

example programs, GnuTLS application examples

examples, GnuTLS application examples

exporting keying material, Keying material exporters

F

FDL, GNU Free Documentation License, Copying Information

G

generating parameters, Parameter generation

GnuTLS client, Invoking gnutls-cli

GnuTLS debug client, Invoking gnutls-cli-debug

GnuTLS OCSP tool, Invoking ocsptool

GnuTLS PKCS #11 tool, Invoking certtool, Invoking p11tool

GnuTLS PSK tool, Invoking psktool

GnuTLS server, Invoking gnutls-serv

GnuTLS SRP tool, Invoking srptool

gnutls-cli, Invoking gnutls-cli

gnutls-cli usage, Invoking gnutls-cli

gnutls-cli-benchmark-ciphers, Invoking gnutls-cli

gnutls-cli-benchmark-soft-ciphers, Invoking gnutls-cli

gnutls-cli-benchmark-tls, Invoking gnutls-cli

gnutls-cli-crlf, Invoking gnutls-cli

gnutls-cli-debug, Invoking gnutls-cli, Invoking gnutls-cli-debug

gnutls-cli-debug usage, Invoking gnutls-cli-debug

gnutls-cli-debug-debug, Invoking gnutls-cli-debug

gnutls-cli-debug-port, Invoking gnutls-cli-debug

gnutls-cli-debug-verbose, Invoking gnutls-cli-debug

gnutls-cli-disable-extensions, Invoking gnutls-cli

gnutls-cli-fingerprint, Invoking gnutls-cli

gnutls-cli-insecure, Invoking gnutls-cli

gnutls-cli-list, Invoking gnutls-cli

gnutls-cli-mtu, Invoking gnutls-cli

gnutls-cli-noticket, Invoking gnutls-cli

gnutls-cli-ocsp, Invoking gnutls-cli

gnutls-cli-pgpcertfile, Invoking gnutls-cli

gnutls-cli-pgpkeyfile, Invoking gnutls-cli

gnutls-cli-pgpkeyring, Invoking gnutls-cli

gnutls-cli-pgpsubkey, Invoking gnutls-cli

gnutls-cli-port, Invoking gnutls-cli

gnutls-cli-print-cert, Invoking gnutls-cli

gnutls-cli-priority, Invoking gnutls-cli

gnutls-cli-pskkey, Invoking gnutls-cli

gnutls-cli-pskusername, Invoking gnutls-cli

gnutls-cli-recordsize, Invoking gnutls-cli

gnutls-cli-rehandshake, Invoking gnutls-cli

gnutls-cli-resume, Invoking gnutls-cli

gnutls-cli-srppasswd, Invoking gnutls-cli

gnutls-cli-srpusername, Invoking gnutls-cli

gnutls-cli-starttls, Invoking gnutls-cli

gnutls-cli-tofu, Invoking gnutls-cli

gnutls-cli-udp, Invoking gnutls-cli

gnutls-cli-verbose, Invoking gnutls-cli

gnutls-cli-x509cafile, Invoking gnutls-cli

gnutls-cli-x509certfile, Invoking gnutls-cli

gnutls-cli-x509crlfile, Invoking gnutls-cli

gnutls-cli-x509fmtder, Invoking gnutls-cli

gnutls-cli-x509keyfile, Invoking gnutls-cli

gnutls-serv, Invoking gnutls-serv

gnutls-serv usage, Invoking gnutls-serv

gnutls-serv-debug, Invoking gnutls-serv

gnutls-serv-dhparams, Invoking gnutls-serv

gnutls-serv-disable-client-cert, Invoking gnutls-serv

gnutls-serv-echo, Invoking gnutls-serv

gnutls-serv-generate, Invoking gnutls-serv

gnutls-serv-http, Invoking gnutls-serv

gnutls-serv-list, Invoking gnutls-serv

gnutls-serv-mtu, Invoking gnutls-serv

gnutls-serv-nodb, Invoking gnutls-serv

gnutls-serv-noticket, Invoking gnutls-serv

gnutls-serv-pgpcertfile, Invoking gnutls-serv

gnutls-serv-pgpkeyfile, Invoking gnutls-serv

gnutls-serv-pgpkeyring, Invoking gnutls-serv

gnutls-serv-pgpsubkey, Invoking gnutls-serv

gnutls-serv-port, Invoking gnutls-serv

gnutls-serv-priority, Invoking gnutls-serv

gnutls-serv-pskhint, Invoking gnutls-serv

gnutls-serv-pskpasswd, Invoking gnutls-serv

gnutls-serv-quiet, Invoking gnutls-serv

gnutls-serv-require-client-cert, Invoking gnutls-serv

gnutls-serv-srppasswd, Invoking gnutls-serv

gnutls-serv-srppasswdconf, Invoking gnutls-serv

gnutls-serv-udp, Invoking gnutls-serv

gnutls-serv-x509cafile, Invoking gnutls-serv

gnutls-serv-x509certfile, Invoking gnutls-serv

gnutls-serv-x509crlfile, Invoking gnutls-serv

gnutls-serv-x509dsacertfile, Invoking gnutls-serv

gnutls-serv-x509dsakeyfile, Invoking gnutls-serv

gnutls-serv-x509ecccertfile, Invoking gnutls-serv

gnutls-serv-x509ecckeyfile, Invoking gnutls-serv

gnutls-serv-x509fmtder, Invoking gnutls-serv

gnutls-serv-x509keyfile, Invoking gnutls-serv

gnutls_alert_get, Core TLS API

gnutls_alert_get_name, Core TLS API

gnutls_alert_get_strname, Core TLS API

gnutls_alert_send, Core TLS API

gnutls_alert_send_appropriate, Core TLS API

gnutls_anon_allocate_client_credentials, Core TLS API

gnutls_anon_allocate_server_credentials, Core TLS API

gnutls_anon_free_client_credentials, Core TLS API

gnutls_anon_free_server_credentials, Core TLS API

gnutls_anon_set_params_function, Core TLS API

gnutls_anon_set_server_dh_params, Core TLS API

gnutls_anon_set_server_params_function, Core TLS API

gnutls_auth_client_get_type, Core TLS API

gnutls_auth_get_type, Core TLS API

gnutls_auth_server_get_type, Core TLS API

gnutls_bye, Core TLS API

gnutls_certificate_activation_time_peers, Core TLS API

gnutls_certificate_allocate_credentials, Core TLS API

gnutls_certificate_client_get_request_status, Core TLS API

gnutls_certificate_expiration_time_peers, Core TLS API

gnutls_certificate_free_cas, Core TLS API

gnutls_certificate_free_ca_names, Core TLS API

gnutls_certificate_free_credentials, Core TLS API

gnutls_certificate_free_crls, Core TLS API

gnutls_certificate_free_keys, Core TLS API

gnutls_certificate_get_issuer, Core TLS API

gnutls_certificate_get_ours, Core TLS API

gnutls_certificate_get_peers, Core TLS API

gnutls_certificate_send_x509_rdn_sequence, Core TLS API

gnutls_certificate_server_set_request, Core TLS API

gnutls_certificate_set_dh_params, Core TLS API

gnutls_certificate_set_key, Abstract key API

gnutls_certificate_set_openpgp_key, OpenPGP API

gnutls_certificate_set_openpgp_keyring_file, OpenPGP API

gnutls_certificate_set_openpgp_keyring_mem, OpenPGP API

gnutls_certificate_set_openpgp_key_file, OpenPGP API

gnutls_certificate_set_openpgp_key_file2, OpenPGP API

gnutls_certificate_set_openpgp_key_mem, OpenPGP API

gnutls_certificate_set_openpgp_key_mem2, OpenPGP API

gnutls_certificate_set_params_function, Core TLS API

gnutls_certificate_set_retrieve_function, Core TLS API

gnutls_certificate_set_retrieve_function2, Abstract key API

gnutls_certificate_set_rsa_export_params, Compatibility API

gnutls_certificate_set_verify_flags, Core TLS API

gnutls_certificate_set_verify_function, Core TLS API

gnutls_certificate_set_verify_limits, Core TLS API

gnutls_certificate_set_x509_crl, Core TLS API

gnutls_certificate_set_x509_crl_file, Core TLS API

gnutls_certificate_set_x509_crl_mem, Core TLS API

gnutls_certificate_set_x509_key, Core TLS API

gnutls_certificate_set_x509_key_file, Core TLS API

gnutls_certificate_set_x509_key_mem, Core TLS API

gnutls_certificate_set_x509_simple_pkcs12_file, Core TLS API

gnutls_certificate_set_x509_simple_pkcs12_mem, Core TLS API

gnutls_certificate_set_x509_trust, Core TLS API

gnutls_certificate_set_x509_trust_file, Core TLS API

gnutls_certificate_set_x509_trust_mem, Core TLS API

gnutls_certificate_type_get, Core TLS API

gnutls_certificate_type_get_id, Core TLS API

gnutls_certificate_type_get_name, Core TLS API

gnutls_certificate_type_list, Core TLS API

gnutls_certificate_type_set_priority, Compatibility API

gnutls_certificate_verify_flags, Verifying a certificate in the context of TLS session, Verifying a certificate using trust on first use authentication

gnutls_certificate_verify_peers2, Core TLS API

gnutls_check_version, Core TLS API

gnutls_cipher_add_auth, Cryptographic API

gnutls_cipher_decrypt, Cryptographic API

gnutls_cipher_decrypt2, Cryptographic API

gnutls_cipher_deinit, Cryptographic API

gnutls_cipher_encrypt, Cryptographic API

gnutls_cipher_encrypt2, Cryptographic API

gnutls_cipher_get, Core TLS API

gnutls_cipher_get_block_size, Cryptographic API

gnutls_cipher_get_id, Core TLS API

gnutls_cipher_get_key_size, Core TLS API

gnutls_cipher_get_name, Core TLS API

gnutls_cipher_init, Cryptographic API

gnutls_cipher_list, Core TLS API

gnutls_cipher_set_iv, Cryptographic API

gnutls_cipher_set_priority, Compatibility API

gnutls_cipher_suite_get_name, Core TLS API

gnutls_cipher_suite_info, Core TLS API

gnutls_cipher_tag, Cryptographic API

gnutls_compression_get, Core TLS API

gnutls_compression_get_id, Core TLS API

gnutls_compression_get_name, Core TLS API

gnutls_compression_list, Core TLS API

gnutls_compression_set_priority, Compatibility API

gnutls_credentials_clear, Core TLS API

gnutls_credentials_set, Core TLS API

gnutls_db_check_entry, Core TLS API

gnutls_db_get_ptr, Core TLS API

gnutls_db_remove_session, Core TLS API

gnutls_db_set_cache_expiration, Core TLS API

gnutls_db_set_ptr, Core TLS API

gnutls_db_set_remove_function, Core TLS API

gnutls_db_set_retrieve_function, Core TLS API

gnutls_db_set_store_function, Core TLS API

gnutls_deinit, Core TLS API

gnutls_dh_get_group, Core TLS API

gnutls_dh_get_peers_public_bits, Core TLS API

gnutls_dh_get_prime_bits, Core TLS API

gnutls_dh_get_pubkey, Core TLS API

gnutls_dh_get_secret_bits, Core TLS API

gnutls_dh_params_cpy, Core TLS API

gnutls_dh_params_deinit, Core TLS API

gnutls_dh_params_export_pkcs3, Core TLS API

gnutls_dh_params_export_raw, Core TLS API

gnutls_dh_params_generate2, Core TLS API

gnutls_dh_params_import_pkcs3, Core TLS API

gnutls_dh_params_import_raw, Core TLS API

gnutls_dh_params_init, Core TLS API

gnutls_dh_set_prime_bits, Core TLS API

gnutls_dtls_cookie_send, Datagram TLS API

gnutls_dtls_cookie_verify, Datagram TLS API

gnutls_dtls_get_data_mtu, Datagram TLS API

gnutls_dtls_get_mtu, Datagram TLS API

gnutls_dtls_get_timeout, Datagram TLS API

gnutls_dtls_prestate_set, Datagram TLS API

gnutls_dtls_set_mtu, Datagram TLS API

gnutls_dtls_set_timeouts, Datagram TLS API

gnutls_ecc_curve_get, Core TLS API

gnutls_ecc_curve_get_name, Core TLS API

gnutls_ecc_curve_get_size, Core TLS API

gnutls_ecc_curve_list, Core TLS API

gnutls_error_is_fatal, Core TLS API

gnutls_error_to_alert, Core TLS API

gnutls_fingerprint, Core TLS API

gnutls_global_deinit, Core TLS API

gnutls_global_init, Core TLS API

gnutls_global_set_audit_log_function, Core TLS API

gnutls_global_set_log_function, Core TLS API

gnutls_global_set_log_level, Core TLS API

gnutls_global_set_mem_functions, Core TLS API

gnutls_global_set_mutex, Core TLS API

gnutls_global_set_time_function, Core TLS API

gnutls_handshake, Core TLS API

gnutls_handshake_get_last_in, Core TLS API

gnutls_handshake_get_last_out, Core TLS API

gnutls_handshake_set_max_packet_length, Core TLS API

gnutls_handshake_set_post_client_hello_function, Core TLS API

gnutls_handshake_set_private_extensions, Core TLS API

gnutls_hash, Cryptographic API

gnutls_hash_deinit, Cryptographic API

gnutls_hash_fast, Cryptographic API

gnutls_hash_get_len, Cryptographic API

gnutls_hash_init, Cryptographic API

gnutls_hash_output, Cryptographic API

gnutls_hex2bin, Core TLS API

gnutls_hex_decode, Core TLS API

gnutls_hex_encode, Core TLS API

gnutls_hmac, Cryptographic API

gnutls_hmac_deinit, Cryptographic API

gnutls_hmac_fast, Cryptographic API

gnutls_hmac_get_len, Cryptographic API

gnutls_hmac_init, Cryptographic API

gnutls_hmac_output, Cryptographic API

gnutls_init, Core TLS API

gnutls_key_generate, Core TLS API

gnutls_kx_get, Core TLS API

gnutls_kx_get_id, Core TLS API

gnutls_kx_get_name, Core TLS API

gnutls_kx_list, Core TLS API

gnutls_kx_set_priority, Compatibility API

gnutls_mac_get, Core TLS API

gnutls_mac_get_id, Core TLS API

gnutls_mac_get_key_size, Core TLS API

gnutls_mac_get_name, Core TLS API

gnutls_mac_list, Core TLS API

gnutls_mac_set_priority, Compatibility API

gnutls_ocsp_req_add_cert, OCSP API

gnutls_ocsp_req_add_cert_id, OCSP API

gnutls_ocsp_req_deinit, OCSP API

gnutls_ocsp_req_export, OCSP API

gnutls_ocsp_req_get_cert_id, OCSP API

gnutls_ocsp_req_get_extension, OCSP API

gnutls_ocsp_req_get_nonce, OCSP API

gnutls_ocsp_req_get_version, OCSP API

gnutls_ocsp_req_import, OCSP API

gnutls_ocsp_req_init, OCSP API

gnutls_ocsp_req_print, OCSP API

gnutls_ocsp_req_randomize_nonce, OCSP API

gnutls_ocsp_req_set_extension, OCSP API

gnutls_ocsp_req_set_nonce, OCSP API

gnutls_ocsp_resp_deinit, OCSP API

gnutls_ocsp_resp_export, OCSP API

gnutls_ocsp_resp_get_certs, OCSP API

gnutls_ocsp_resp_get_extension, OCSP API

gnutls_ocsp_resp_get_nonce, OCSP API

gnutls_ocsp_resp_get_produced, OCSP API

gnutls_ocsp_resp_get_responder, OCSP API

gnutls_ocsp_resp_get_response, OCSP API

gnutls_ocsp_resp_get_signature, OCSP API

gnutls_ocsp_resp_get_signature_algorithm, OCSP API

gnutls_ocsp_resp_get_single, OCSP API

gnutls_ocsp_resp_get_status, OCSP API

gnutls_ocsp_resp_get_version, OCSP API

gnutls_ocsp_resp_import, OCSP API

gnutls_ocsp_resp_init, OCSP API

gnutls_ocsp_resp_print, OCSP API

gnutls_ocsp_resp_verify, OCSP API

gnutls_ocsp_resp_verify_direct, OCSP API

gnutls_openpgp_crt_check_hostname, OpenPGP API

gnutls_openpgp_crt_deinit, OpenPGP API

gnutls_openpgp_crt_export, OpenPGP API

gnutls_openpgp_crt_get_auth_subkey, OpenPGP API

gnutls_openpgp_crt_get_creation_time, OpenPGP API

gnutls_openpgp_crt_get_expiration_time, OpenPGP API

gnutls_openpgp_crt_get_fingerprint, OpenPGP API

gnutls_openpgp_crt_get_key_id, OpenPGP API

gnutls_openpgp_crt_get_key_usage, OpenPGP API

gnutls_openpgp_crt_get_name, OpenPGP API

gnutls_openpgp_crt_get_pk_algorithm, OpenPGP API

gnutls_openpgp_crt_get_pk_dsa_raw, OpenPGP API

gnutls_openpgp_crt_get_pk_rsa_raw, OpenPGP API

gnutls_openpgp_crt_get_preferred_key_id, OpenPGP API

gnutls_openpgp_crt_get_revoked_status, OpenPGP API

gnutls_openpgp_crt_get_subkey_count, OpenPGP API

gnutls_openpgp_crt_get_subkey_creation_time, OpenPGP API

gnutls_openpgp_crt_get_subkey_expiration_time, OpenPGP API

gnutls_openpgp_crt_get_subkey_fingerprint, OpenPGP API

gnutls_openpgp_crt_get_subkey_id, OpenPGP API

gnutls_openpgp_crt_get_subkey_idx, OpenPGP API

gnutls_openpgp_crt_get_subkey_pk_algorithm, OpenPGP API

gnutls_openpgp_crt_get_subkey_pk_dsa_raw, OpenPGP API

gnutls_openpgp_crt_get_subkey_pk_rsa_raw, OpenPGP API

gnutls_openpgp_crt_get_subkey_revoked_status, OpenPGP API

gnutls_openpgp_crt_get_subkey_usage, OpenPGP API

gnutls_openpgp_crt_get_version, OpenPGP API

gnutls_openpgp_crt_import, OpenPGP API

gnutls_openpgp_crt_init, OpenPGP API

gnutls_openpgp_crt_print, OpenPGP API

gnutls_openpgp_crt_set_preferred_key_id, OpenPGP API

gnutls_openpgp_crt_verify_ring, OpenPGP API

gnutls_openpgp_crt_verify_self, OpenPGP API

gnutls_openpgp_keyring_check_id, OpenPGP API

gnutls_openpgp_keyring_deinit, OpenPGP API

gnutls_openpgp_keyring_get_crt, OpenPGP API

gnutls_openpgp_keyring_get_crt_count, OpenPGP API

gnutls_openpgp_keyring_import, OpenPGP API

gnutls_openpgp_keyring_init, OpenPGP API

gnutls_openpgp_privkey_deinit, OpenPGP API

gnutls_openpgp_privkey_export, OpenPGP API

gnutls_openpgp_privkey_export_dsa_raw, OpenPGP API

gnutls_openpgp_privkey_export_rsa_raw, OpenPGP API

gnutls_openpgp_privkey_export_subkey_dsa_raw, OpenPGP API

gnutls_openpgp_privkey_export_subkey_rsa_raw, OpenPGP API

gnutls_openpgp_privkey_get_fingerprint, OpenPGP API

gnutls_openpgp_privkey_get_key_id, OpenPGP API

gnutls_openpgp_privkey_get_pk_algorithm, OpenPGP API

gnutls_openpgp_privkey_get_preferred_key_id, OpenPGP API

gnutls_openpgp_privkey_get_revoked_status, OpenPGP API

gnutls_openpgp_privkey_get_subkey_count, OpenPGP API

gnutls_openpgp_privkey_get_subkey_creation_time, OpenPGP API

gnutls_openpgp_privkey_get_subkey_fingerprint, OpenPGP API

gnutls_openpgp_privkey_get_subkey_id, OpenPGP API

gnutls_openpgp_privkey_get_subkey_idx, OpenPGP API

gnutls_openpgp_privkey_get_subkey_pk_algorithm, OpenPGP API

gnutls_openpgp_privkey_get_subkey_revoked_status, OpenPGP API

gnutls_openpgp_privkey_import, OpenPGP API

gnutls_openpgp_privkey_init, OpenPGP API

gnutls_openpgp_privkey_sec_param, OpenPGP API

gnutls_openpgp_privkey_set_preferred_key_id, OpenPGP API

gnutls_openpgp_privkey_sign_hash, Compatibility API

gnutls_openpgp_send_cert, Core TLS API

gnutls_openpgp_set_recv_key_function, OpenPGP API

gnutls_pcert_deinit, Abstract key API

gnutls_pcert_import_openpgp, Abstract key API

gnutls_pcert_import_openpgp_raw, Abstract key API

gnutls_pcert_import_x509, Abstract key API

gnutls_pcert_import_x509_raw, Abstract key API

gnutls_pcert_list_import_x509_raw, Abstract key API

gnutls_pem_base64_decode, Core TLS API

gnutls_pem_base64_decode_alloc, Core TLS API

gnutls_pem_base64_encode, Core TLS API

gnutls_pem_base64_encode_alloc, Core TLS API

gnutls_perror, Core TLS API

gnutls_pkcs11_add_provider, Hardware token via PKCS 11 API

gnutls_pkcs11_copy_secret_key, Hardware token via PKCS 11 API

gnutls_pkcs11_copy_x509_crt, Hardware token via PKCS 11 API

gnutls_pkcs11_copy_x509_privkey, Hardware token via PKCS 11 API

gnutls_pkcs11_deinit, Hardware token via PKCS 11 API

gnutls_pkcs11_delete_url, Hardware token via PKCS 11 API

gnutls_pkcs11_init, Hardware token via PKCS 11 API

gnutls_pkcs11_obj_deinit, Hardware token via PKCS 11 API

gnutls_pkcs11_obj_export, Hardware token via PKCS 11 API

gnutls_pkcs11_obj_export_url, Hardware token via PKCS 11 API

gnutls_pkcs11_obj_get_info, Hardware token via PKCS 11 API

gnutls_pkcs11_obj_get_type, Hardware token via PKCS 11 API

gnutls_pkcs11_obj_import_url, Hardware token via PKCS 11 API

gnutls_pkcs11_obj_init, Hardware token via PKCS 11 API

gnutls_pkcs11_obj_list_import_url, Hardware token via PKCS 11 API

gnutls_pkcs11_privkey_deinit, Hardware token via PKCS 11 API

gnutls_pkcs11_privkey_export_url, Hardware token via PKCS 11 API

gnutls_pkcs11_privkey_generate, Hardware token via PKCS 11 API

gnutls_pkcs11_privkey_get_info, Hardware token via PKCS 11 API

gnutls_pkcs11_privkey_get_pk_algorithm, Hardware token via PKCS 11 API

gnutls_pkcs11_privkey_import_url, Hardware token via PKCS 11 API

gnutls_pkcs11_privkey_init, Hardware token via PKCS 11 API

gnutls_pkcs11_reinit, Hardware token via PKCS 11 API

gnutls_pkcs11_set_pin_function, Hardware token via PKCS 11 API

gnutls_pkcs11_set_token_function, Hardware token via PKCS 11 API

gnutls_pkcs11_token_get_flags, Hardware token via PKCS 11 API

gnutls_pkcs11_token_get_info, Hardware token via PKCS 11 API

gnutls_pkcs11_token_get_mechanism, Hardware token via PKCS 11 API

gnutls_pkcs11_token_get_url, Hardware token via PKCS 11 API

gnutls_pkcs11_token_init, Hardware token via PKCS 11 API

gnutls_pkcs11_token_set_pin, Hardware token via PKCS 11 API

gnutls_pkcs11_type_get_name, Hardware token via PKCS 11 API

gnutls_pkcs12_bag_decrypt, PKCS 12 API

gnutls_pkcs12_bag_deinit, PKCS 12 API

gnutls_pkcs12_bag_encrypt, PKCS 12 API

gnutls_pkcs12_bag_get_count, PKCS 12 API

gnutls_pkcs12_bag_get_data, PKCS 12 API

gnutls_pkcs12_bag_get_friendly_name, PKCS 12 API

gnutls_pkcs12_bag_get_key_id, PKCS 12 API

gnutls_pkcs12_bag_get_type, PKCS 12 API

gnutls_pkcs12_bag_init, PKCS 12 API

gnutls_pkcs12_bag_set_crl, PKCS 12 API

gnutls_pkcs12_bag_set_crt, PKCS 12 API

gnutls_pkcs12_bag_set_data, PKCS 12 API

gnutls_pkcs12_bag_set_friendly_name, PKCS 12 API

gnutls_pkcs12_bag_set_key_id, PKCS 12 API

gnutls_pkcs12_deinit, PKCS 12 API

gnutls_pkcs12_export, PKCS 12 API

gnutls_pkcs12_generate_mac, PKCS 12 API

gnutls_pkcs12_get_bag, PKCS 12 API

gnutls_pkcs12_import, PKCS 12 API

gnutls_pkcs12_init, PKCS 12 API

gnutls_pkcs12_set_bag, PKCS 12 API

gnutls_pkcs12_verify_mac, PKCS 12 API

gnutls_pkcs7_deinit, X.509 certificate API

gnutls_pkcs7_delete_crl, X.509 certificate API

gnutls_pkcs7_delete_crt, X.509 certificate API

gnutls_pkcs7_export, X.509 certificate API

gnutls_pkcs7_get_crl_count, X.509 certificate API

gnutls_pkcs7_get_crl_raw, X.509 certificate API

gnutls_pkcs7_get_crt_count, X.509 certificate API

gnutls_pkcs7_get_crt_raw, X.509 certificate API

gnutls_pkcs7_import, X.509 certificate API

gnutls_pkcs7_init, X.509 certificate API

gnutls_pkcs7_set_crl, X.509 certificate API

gnutls_pkcs7_set_crl_raw, X.509 certificate API

gnutls_pkcs7_set_crt, X.509 certificate API

gnutls_pkcs7_set_crt_raw, X.509 certificate API

gnutls_pk_algorithm_get_name, Core TLS API

gnutls_pk_bits_to_sec_param, Core TLS API

gnutls_pk_get_id, Core TLS API

gnutls_pk_get_name, Core TLS API

gnutls_pk_list, Core TLS API

gnutls_prf, Core TLS API

gnutls_prf_raw, Core TLS API

gnutls_priority_certificate_type_list, Core TLS API

gnutls_priority_compression_list, Core TLS API

gnutls_priority_deinit, Core TLS API

gnutls_priority_ecc_curve_list, Core TLS API

gnutls_priority_get_cipher_suite_index, Core TLS API

gnutls_priority_init, Core TLS API

gnutls_priority_protocol_list, Core TLS API

gnutls_priority_set, Core TLS API

gnutls_priority_set_direct, Core TLS API

gnutls_priority_sign_list, Core TLS API

gnutls_privkey_decrypt_data, Abstract key API

gnutls_privkey_deinit, Abstract key API

gnutls_privkey_get_pk_algorithm, Abstract key API

gnutls_privkey_get_type, Abstract key API

gnutls_privkey_import_ext, Abstract key API

gnutls_privkey_import_openpgp, Abstract key API

gnutls_privkey_import_pkcs11, Abstract key API

gnutls_privkey_import_x509, Abstract key API

gnutls_privkey_init, Abstract key API

gnutls_privkey_sign_data, Abstract key API

gnutls_privkey_sign_hash, Abstract key API

gnutls_protocol_get_id, Core TLS API

gnutls_protocol_get_name, Core TLS API

gnutls_protocol_get_version, Core TLS API

gnutls_protocol_list, Core TLS API

gnutls_protocol_set_priority, Compatibility API

gnutls_psk_allocate_client_credentials, Core TLS API

gnutls_psk_allocate_server_credentials, Core TLS API

gnutls_psk_client_get_hint, Core TLS API

gnutls_psk_free_client_credentials, Core TLS API

gnutls_psk_free_server_credentials, Core TLS API

gnutls_psk_server_get_username, Core TLS API

gnutls_psk_set_client_credentials, Core TLS API

gnutls_psk_set_client_credentials_function, Core TLS API

gnutls_psk_set_params_function, Core TLS API

gnutls_psk_set_server_credentials_file, Core TLS API

gnutls_psk_set_server_credentials_function, Core TLS API

gnutls_psk_set_server_credentials_hint, Core TLS API

gnutls_psk_set_server_dh_params, Core TLS API

gnutls_psk_set_server_params_function, Core TLS API

gnutls_pubkey_deinit, Abstract key API

gnutls_pubkey_encrypt_data, Abstract key API

gnutls_pubkey_export, Abstract key API

gnutls_pubkey_get_key_id, Abstract key API

gnutls_pubkey_get_key_usage, Abstract key API

gnutls_pubkey_get_openpgp_key_id, Abstract key API

gnutls_pubkey_get_pk_algorithm, Abstract key API

gnutls_pubkey_get_pk_dsa_raw, Abstract key API

gnutls_pubkey_get_pk_ecc_raw, Abstract key API

gnutls_pubkey_get_pk_ecc_x962, Abstract key API

gnutls_pubkey_get_pk_rsa_raw, Abstract key API

gnutls_pubkey_get_preferred_hash_algorithm, Abstract key API

gnutls_pubkey_get_verify_algorithm, Abstract key API

gnutls_pubkey_import, Abstract key API

gnutls_pubkey_import_dsa_raw, Abstract key API

gnutls_pubkey_import_ecc_raw, Abstract key API

gnutls_pubkey_import_ecc_x962, Abstract key API

gnutls_pubkey_import_openpgp, Abstract key API

gnutls_pubkey_import_pkcs11, Abstract key API

gnutls_pubkey_import_pkcs11_url, Abstract key API

gnutls_pubkey_import_privkey, Abstract key API

gnutls_pubkey_import_rsa_raw, Abstract key API

gnutls_pubkey_import_x509, Abstract key API

gnutls_pubkey_init, Abstract key API

gnutls_pubkey_set_key_usage, Abstract key API

gnutls_pubkey_verify_data, Abstract key API

gnutls_pubkey_verify_data2, Abstract key API

gnutls_pubkey_verify_hash, Abstract key API

gnutls_random_art, Core TLS API

gnutls_record_check_pending, Core TLS API

gnutls_record_disable_padding, Core TLS API

gnutls_record_get_direction, Core TLS API

gnutls_record_get_discarded, Datagram TLS API

gnutls_record_get_max_size, Core TLS API

gnutls_record_recv, Core TLS API

gnutls_record_recv_seq, Core TLS API

gnutls_record_send, Core TLS API

gnutls_record_set_max_size, Core TLS API

gnutls_rehandshake, Core TLS API

gnutls_rnd, Cryptographic API

gnutls_rsa_export_get_modulus_bits, Compatibility API

gnutls_rsa_export_get_pubkey, Compatibility API

gnutls_rsa_params_cpy, Compatibility API

gnutls_rsa_params_deinit, Compatibility API

gnutls_rsa_params_export_pkcs1, Compatibility API

gnutls_rsa_params_export_raw, Compatibility API

gnutls_rsa_params_generate2, Compatibility API

gnutls_rsa_params_import_pkcs1, Compatibility API

gnutls_rsa_params_import_raw, Compatibility API

gnutls_rsa_params_init, Compatibility API

gnutls_safe_renegotiation_status, Core TLS API

gnutls_sec_param_get_name, Core TLS API

gnutls_sec_param_to_pk_bits, Core TLS API

gnutls_server_name_get, Core TLS API

gnutls_server_name_set, Core TLS API

gnutls_session_channel_binding, Core TLS API

gnutls_session_enable_compatibility_mode, Core TLS API

gnutls_session_get_data, Core TLS API

gnutls_session_get_data2, Core TLS API

gnutls_session_get_id, Core TLS API

gnutls_session_get_ptr, Core TLS API

gnutls_session_get_random, Core TLS API

gnutls_session_is_resumed, Core TLS API

gnutls_session_resumption_requested, Core TLS API

gnutls_session_set_data, Core TLS API

gnutls_session_set_ptr, Core TLS API

gnutls_session_ticket_enable_client, Core TLS API

gnutls_session_ticket_enable_server, Core TLS API

gnutls_session_ticket_key_generate, Core TLS API

gnutls_set_default_export_priority, Compatibility API

gnutls_set_default_priority, Core TLS API

gnutls_sign_algorithm_get_requested, Core TLS API

gnutls_sign_callback_get, Compatibility API

gnutls_sign_callback_set, Compatibility API

gnutls_sign_get_id, Core TLS API

gnutls_sign_get_name, Core TLS API

gnutls_sign_list, Core TLS API

gnutls_srp_allocate_client_credentials, Core TLS API

gnutls_srp_allocate_server_credentials, Core TLS API

gnutls_srp_base64_decode, Core TLS API

gnutls_srp_base64_decode_alloc, Core TLS API

gnutls_srp_base64_encode, Core TLS API

gnutls_srp_base64_encode_alloc, Core TLS API

gnutls_srp_free_client_credentials, Core TLS API

gnutls_srp_free_server_credentials, Core TLS API

gnutls_srp_server_get_username, Core TLS API

gnutls_srp_set_client_credentials, Core TLS API

gnutls_srp_set_client_credentials_function, Core TLS API

gnutls_srp_set_prime_bits, Core TLS API

gnutls_srp_set_server_credentials_file, Core TLS API

gnutls_srp_set_server_credentials_function, Core TLS API

gnutls_srp_verifier, Core TLS API

gnutls_store_commitment, Core TLS API

gnutls_store_pubkey, Core TLS API

gnutls_strerror, Core TLS API

gnutls_strerror_name, Core TLS API

gnutls_supplemental_get_name, Core TLS API

gnutls_tdb_deinit, Core TLS API

gnutls_tdb_init, Core TLS API

gnutls_tdb_set_store_commitment_func, Core TLS API

gnutls_tdb_set_store_func, Core TLS API

gnutls_tdb_set_verify_func, Core TLS API

gnutls_transport_get_ptr, Core TLS API

gnutls_transport_get_ptr2, Core TLS API

gnutls_transport_set_errno, Core TLS API

gnutls_transport_set_errno_function, Core TLS API

gnutls_transport_set_ptr, Core TLS API

gnutls_transport_set_ptr2, Core TLS API

gnutls_transport_set_pull_function, Core TLS API

gnutls_transport_set_pull_timeout_function, Core TLS API

gnutls_transport_set_push_function, Core TLS API

gnutls_transport_set_vec_push_function, Core TLS API

gnutls_verify_stored_pubkey, Core TLS API

gnutls_x509_crl_check_issuer, X.509 certificate API

gnutls_x509_crl_deinit, X.509 certificate API

gnutls_x509_crl_export, X.509 certificate API

gnutls_x509_crl_get_authority_key_gn_serial, X.509 certificate API

gnutls_x509_crl_get_authority_key_id, X.509 certificate API

gnutls_x509_crl_get_crt_count, X.509 certificate API

gnutls_x509_crl_get_crt_serial, X.509 certificate API

gnutls_x509_crl_get_dn_oid, X.509 certificate API

gnutls_x509_crl_get_extension_data, X.509 certificate API

gnutls_x509_crl_get_extension_info, X.509 certificate API

gnutls_x509_crl_get_extension_oid, X.509 certificate API

gnutls_x509_crl_get_issuer_dn, X.509 certificate API

gnutls_x509_crl_get_issuer_dn_by_oid, X.509 certificate API

gnutls_x509_crl_get_next_update, X.509 certificate API

gnutls_x509_crl_get_number, X.509 certificate API

gnutls_x509_crl_get_raw_issuer_dn, X.509 certificate API

gnutls_x509_crl_get_signature, X.509 certificate API

gnutls_x509_crl_get_signature_algorithm, X.509 certificate API

gnutls_x509_crl_get_this_update, X.509 certificate API

gnutls_x509_crl_get_version, X.509 certificate API

gnutls_x509_crl_import, X.509 certificate API

gnutls_x509_crl_init, X.509 certificate API

gnutls_x509_crl_list_import, X.509 certificate API

gnutls_x509_crl_list_import2, X.509 certificate API

gnutls_x509_crl_print, X.509 certificate API

gnutls_x509_crl_privkey_sign, Abstract key API

gnutls_x509_crl_set_authority_key_id, X.509 certificate API

gnutls_x509_crl_set_crt, X.509 certificate API

gnutls_x509_crl_set_crt_serial, X.509 certificate API

gnutls_x509_crl_set_next_update, X.509 certificate API

gnutls_x509_crl_set_number, X.509 certificate API

gnutls_x509_crl_set_this_update, X.509 certificate API

gnutls_x509_crl_set_version, X.509 certificate API

gnutls_x509_crl_sign, Compatibility API

gnutls_x509_crl_sign2, X.509 certificate API

gnutls_x509_crl_verify, X.509 certificate API

gnutls_x509_crq_deinit, X.509 certificate API

gnutls_x509_crq_export, X.509 certificate API

gnutls_x509_crq_get_attribute_by_oid, X.509 certificate API

gnutls_x509_crq_get_attribute_data, X.509 certificate API

gnutls_x509_crq_get_attribute_info, X.509 certificate API

gnutls_x509_crq_get_basic_constraints, X.509 certificate API

gnutls_x509_crq_get_challenge_password, X.509 certificate API

gnutls_x509_crq_get_dn, X.509 certificate API

gnutls_x509_crq_get_dn_by_oid, X.509 certificate API

gnutls_x509_crq_get_dn_oid, X.509 certificate API

gnutls_x509_crq_get_extension_by_oid, X.509 certificate API

gnutls_x509_crq_get_extension_data, X.509 certificate API

gnutls_x509_crq_get_extension_info, X.509 certificate API

gnutls_x509_crq_get_key_id, X.509 certificate API

gnutls_x509_crq_get_key_purpose_oid, X.509 certificate API

gnutls_x509_crq_get_key_rsa_raw, X.509 certificate API

gnutls_x509_crq_get_key_usage, X.509 certificate API

gnutls_x509_crq_get_pk_algorithm, X.509 certificate API

gnutls_x509_crq_get_private_key_usage_period, X.509 certificate API

gnutls_x509_crq_get_subject_alt_name, X.509 certificate API

gnutls_x509_crq_get_subject_alt_othername_oid, X.509 certificate API

gnutls_x509_crq_get_version, X.509 certificate API

gnutls_x509_crq_import, X.509 certificate API

gnutls_x509_crq_init, X.509 certificate API

gnutls_x509_crq_print, X.509 certificate API

gnutls_x509_crq_privkey_sign, Abstract key API

gnutls_x509_crq_set_attribute_by_oid, X.509 certificate API

gnutls_x509_crq_set_basic_constraints, X.509 certificate API

gnutls_x509_crq_set_challenge_password, X.509 certificate API

gnutls_x509_crq_set_dn_by_oid, X.509 certificate API

gnutls_x509_crq_set_key, X.509 certificate API

gnutls_x509_crq_set_key_purpose_oid, X.509 certificate API

gnutls_x509_crq_set_key_rsa_raw, X.509 certificate API

gnutls_x509_crq_set_key_usage, X.509 certificate API

gnutls_x509_crq_set_private_key_usage_period, X.509 certificate API

gnutls_x509_crq_set_pubkey, Abstract key API

gnutls_x509_crq_set_subject_alt_name, X.509 certificate API

gnutls_x509_crq_set_version, X.509 certificate API

gnutls_x509_crq_sign, Compatibility API

gnutls_x509_crq_sign2, X.509 certificate API

gnutls_x509_crq_verify, X.509 certificate API

gnutls_x509_crt_check_hostname, X.509 certificate API

gnutls_x509_crt_check_issuer, X.509 certificate API

gnutls_x509_crt_check_revocation, X.509 certificate API

gnutls_x509_crt_cpy_crl_dist_points, X.509 certificate API

gnutls_x509_crt_deinit, X.509 certificate API

gnutls_x509_crt_export, X.509 certificate API

gnutls_x509_crt_get_activation_time, X.509 certificate API

gnutls_x509_crt_get_authority_info_access, X.509 certificate API

gnutls_x509_crt_get_authority_key_gn_serial, X.509 certificate API

gnutls_x509_crt_get_authority_key_id, X.509 certificate API

gnutls_x509_crt_get_basic_constraints, X.509 certificate API

gnutls_x509_crt_get_ca_status, X.509 certificate API

gnutls_x509_crt_get_crl_dist_points, X.509 certificate API

gnutls_x509_crt_get_dn, X.509 certificate API

gnutls_x509_crt_get_dn_by_oid, X.509 certificate API

gnutls_x509_crt_get_dn_oid, X.509 certificate API

gnutls_x509_crt_get_expiration_time, X.509 certificate API

gnutls_x509_crt_get_extension_by_oid, X.509 certificate API

gnutls_x509_crt_get_extension_data, X.509 certificate API

gnutls_x509_crt_get_extension_info, X.509 certificate API

gnutls_x509_crt_get_extension_oid, X.509 certificate API

gnutls_x509_crt_get_fingerprint, X.509 certificate API

gnutls_x509_crt_get_issuer, X.509 certificate API

gnutls_x509_crt_get_issuer_alt_name, X.509 certificate API

gnutls_x509_crt_get_issuer_alt_name2, X.509 certificate API

gnutls_x509_crt_get_issuer_alt_othername_oid, X.509 certificate API

gnutls_x509_crt_get_issuer_dn, X.509 certificate API

gnutls_x509_crt_get_issuer_dn_by_oid, X.509 certificate API

gnutls_x509_crt_get_issuer_dn_oid, X.509 certificate API

gnutls_x509_crt_get_issuer_unique_id, X.509 certificate API

gnutls_x509_crt_get_key_id, X.509 certificate API

gnutls_x509_crt_get_key_purpose_oid, X.509 certificate API

gnutls_x509_crt_get_key_usage, X.509 certificate API

gnutls_x509_crt_get_pk_algorithm, X.509 certificate API

gnutls_x509_crt_get_pk_dsa_raw, X.509 certificate API

gnutls_x509_crt_get_pk_rsa_raw, X.509 certificate API

gnutls_x509_crt_get_preferred_hash_algorithm, Compatibility API

gnutls_x509_crt_get_private_key_usage_period, X.509 certificate API

gnutls_x509_crt_get_proxy, X.509 certificate API

gnutls_x509_crt_get_raw_dn, X.509 certificate API

gnutls_x509_crt_get_raw_issuer_dn, X.509 certificate API

gnutls_x509_crt_get_serial, X.509 certificate API

gnutls_x509_crt_get_signature, X.509 certificate API

gnutls_x509_crt_get_signature_algorithm, X.509 certificate API

gnutls_x509_crt_get_subject, X.509 certificate API

gnutls_x509_crt_get_subject_alt_name, X.509 certificate API

gnutls_x509_crt_get_subject_alt_name2, X.509 certificate API

gnutls_x509_crt_get_subject_alt_othername_oid, X.509 certificate API

gnutls_x509_crt_get_subject_key_id, X.509 certificate API

gnutls_x509_crt_get_subject_unique_id, X.509 certificate API

gnutls_x509_crt_get_verify_algorithm, Compatibility API

gnutls_x509_crt_get_version, X.509 certificate API

gnutls_x509_crt_import, X.509 certificate API

gnutls_x509_crt_import_pkcs11, Hardware token via PKCS 11 API

gnutls_x509_crt_import_pkcs11_url, Hardware token via PKCS 11 API

gnutls_x509_crt_init, X.509 certificate API

gnutls_x509_crt_list_import, X.509 certificate API

gnutls_x509_crt_list_import2, X.509 certificate API

gnutls_x509_crt_list_import_pkcs11, Hardware token via PKCS 11 API

gnutls_x509_crt_list_verify, X.509 certificate API

gnutls_x509_crt_print, X.509 certificate API

gnutls_x509_crt_privkey_sign, Abstract key API

gnutls_x509_crt_set_activation_time, X.509 certificate API

gnutls_x509_crt_set_authority_info_access, X.509 certificate API

gnutls_x509_crt_set_authority_key_id, X.509 certificate API

gnutls_x509_crt_set_basic_constraints, X.509 certificate API

gnutls_x509_crt_set_ca_status, X.509 certificate API

gnutls_x509_crt_set_crl_dist_points, X.509 certificate API

gnutls_x509_crt_set_crl_dist_points2, X.509 certificate API

gnutls_x509_crt_set_crq, X.509 certificate API

gnutls_x509_crt_set_crq_extensions, X.509 certificate API

gnutls_x509_crt_set_dn_by_oid, X.509 certificate API

gnutls_x509_crt_set_expiration_time, X.509 certificate API

gnutls_x509_crt_set_extension_by_oid, X.509 certificate API

gnutls_x509_crt_set_issuer_dn_by_oid, X.509 certificate API

gnutls_x509_crt_set_key, X.509 certificate API

gnutls_x509_crt_set_key_purpose_oid, X.509 certificate API

gnutls_x509_crt_set_key_usage, X.509 certificate API

gnutls_x509_crt_set_private_key_usage_period, X.509 certificate API

gnutls_x509_crt_set_proxy, X.509 certificate API

gnutls_x509_crt_set_proxy_dn, X.509 certificate API

gnutls_x509_crt_set_pubkey, Abstract key API

gnutls_x509_crt_set_serial, X.509 certificate API

gnutls_x509_crt_set_subject_alternative_name, X.509 certificate API

gnutls_x509_crt_set_subject_alt_name, X.509 certificate API

gnutls_x509_crt_set_subject_key_id, X.509 certificate API

gnutls_x509_crt_set_version, X.509 certificate API

gnutls_x509_crt_sign, X.509 certificate API

gnutls_x509_crt_sign2, X.509 certificate API

gnutls_x509_crt_verify, X.509 certificate API

gnutls_x509_crt_verify_data, Compatibility API

gnutls_x509_crt_verify_hash, Compatibility API

gnutls_x509_dn_deinit, X.509 certificate API

gnutls_x509_dn_export, X.509 certificate API

gnutls_x509_dn_get_rdn_ava, X.509 certificate API

gnutls_x509_dn_import, X.509 certificate API

gnutls_x509_dn_init, X.509 certificate API

gnutls_x509_dn_oid_known, X.509 certificate API

gnutls_x509_dn_oid_name, X.509 certificate API

gnutls_x509_privkey_cpy, X.509 certificate API

gnutls_x509_privkey_deinit, X.509 certificate API

gnutls_x509_privkey_export, X.509 certificate API

gnutls_x509_privkey_export_dsa_raw, X.509 certificate API

gnutls_x509_privkey_export_ecc_raw, X.509 certificate API

gnutls_x509_privkey_export_pkcs8, X.509 certificate API

gnutls_x509_privkey_export_rsa_raw, X.509 certificate API

gnutls_x509_privkey_export_rsa_raw2, X.509 certificate API

gnutls_x509_privkey_fix, X.509 certificate API

gnutls_x509_privkey_generate, X.509 certificate API

gnutls_x509_privkey_get_key_id, X.509 certificate API

gnutls_x509_privkey_get_pk_algorithm, X.509 certificate API

gnutls_x509_privkey_import, X.509 certificate API

gnutls_x509_privkey_import_dsa_raw, X.509 certificate API

gnutls_x509_privkey_import_ecc_raw, X.509 certificate API

gnutls_x509_privkey_import_pkcs8, X.509 certificate API

gnutls_x509_privkey_import_rsa_raw, X.509 certificate API

gnutls_x509_privkey_import_rsa_raw2, X.509 certificate API

gnutls_x509_privkey_init, X.509 certificate API

gnutls_x509_privkey_sec_param, X.509 certificate API

gnutls_x509_privkey_sign_data, Compatibility API

gnutls_x509_privkey_sign_hash, Compatibility API

gnutls_x509_privkey_verify_params, X.509 certificate API

gnutls_x509_rdn_get, X.509 certificate API

gnutls_x509_rdn_get_by_oid, X.509 certificate API

gnutls_x509_rdn_get_oid, X.509 certificate API

gnutls_x509_trust_list_add_cas, X.509 certificate API

gnutls_x509_trust_list_add_crls, X.509 certificate API

gnutls_x509_trust_list_add_named_crt, X.509 certificate API

gnutls_x509_trust_list_deinit, X.509 certificate API

gnutls_x509_trust_list_get_issuer, X.509 certificate API

gnutls_x509_trust_list_init, X.509 certificate API

gnutls_x509_trust_list_verify_crt, X.509 certificate API

gnutls_x509_trust_list_verify_named_crt, X.509 certificate API

H

hacking, Contributing

handshake protocol, The TLS handshake protocol

hardware security modules, Smart cards and HSMs

hardware tokens, Smart cards and HSMs

hash functions, Hash and HMAC functions

HMAC functions, Hash and HMAC functions

I

installation, Downloading and installing

internal architecture, Internal Architecture of GnuTLS

K

Key pinning, Verifying a certificate using trust on first use authentication

key sizes, Selecting cryptographic key sizes

keying material exporters, Keying material exporters

M

maximum fragment length, Maximum fragment length negotiation

O

OCSP, OCSP certificate status checking

OCSP Functions, OCSP API

ocsptool, Invoking ocsptool

ocsptool usage, Invoking ocsptool

ocsptool-ask, Invoking ocsptool

ocsptool-debug, Invoking ocsptool

ocsptool-generate-request, Invoking ocsptool

ocsptool-inder, Invoking ocsptool

ocsptool-infile, Invoking ocsptool

ocsptool-load-cert, Invoking ocsptool

ocsptool-load-issuer, Invoking ocsptool

ocsptool-load-request, Invoking ocsptool

ocsptool-load-response, Invoking ocsptool

ocsptool-load-signer, Invoking ocsptool

ocsptool-load-trust, Invoking ocsptool

ocsptool-nonce, Invoking ocsptool

ocsptool-outfile, Invoking ocsptool

ocsptool-request-info, Invoking ocsptool

ocsptool-response-info, Invoking ocsptool

ocsptool-verbose, Invoking ocsptool

ocsptool-verify-response, Invoking ocsptool

Online Certificate Status Protocol, OCSP certificate status checking

OpenPGP API, OpenPGP API

OpenPGP certificates, OpenPGP certificates

OpenPGP server, Echo server with OpenPGP authentication

OpenSSL, Compatibility with the OpenSSL library

P

p11tool, Invoking p11tool

p11tool usage, Invoking p11tool

p11tool-bits, Invoking p11tool

p11tool-debug, Invoking p11tool

p11tool-delete, Invoking p11tool

p11tool-detailed-url, Invoking p11tool

p11tool-export, Invoking p11tool

p11tool-generate-dsa, Invoking p11tool

p11tool-generate-ecc, Invoking p11tool

p11tool-generate-rsa, Invoking p11tool

p11tool-inder, Invoking p11tool

p11tool-initialize, Invoking p11tool

p11tool-inraw, Invoking p11tool

p11tool-label, Invoking p11tool

p11tool-list-all, Invoking p11tool

p11tool-list-all-certs, Invoking p11tool

p11tool-list-all-privkeys, Invoking p11tool

p11tool-list-all-trusted, Invoking p11tool

p11tool-list-certs, Invoking p11tool

p11tool-list-mechanisms, Invoking p11tool

p11tool-list-tokens, Invoking p11tool

p11tool-load-certificate, Invoking p11tool

p11tool-load-privkey, Invoking p11tool

p11tool-load-pubkey, Invoking p11tool

p11tool-login, Invoking p11tool

p11tool-outfile, Invoking p11tool

p11tool-pkcs8, Invoking p11tool

p11tool-private, Invoking p11tool

p11tool-provider, Invoking p11tool

p11tool-sec-param, Invoking p11tool

p11tool-secret-key, Invoking p11tool

p11tool-trusted, Invoking p11tool

p11tool-write, Invoking p11tool

parameter generation, Parameter generation

PCT, On SSL 2 and older protocols

PKCS #10, PKCS #10 certificate requests

PKCS #11 tokens, Smart cards and HSMs

PKCS #12, Managing encrypted keys

PKCS #8, Managing encrypted keys

Priority strings, Priority strings

PSK authentication, Authentication using PSK

psktool, Invoking psktool

psktool usage, Invoking psktool

psktool-debug, Invoking psktool

psktool-keysize, Invoking psktool

psktool-passwd, Invoking psktool

psktool-username, Invoking psktool

R

random numbers, Random number generation

record padding, On record padding

record protocol, The TLS record protocol

renegotiation, Safe renegotiation

reporting bugs, Bug Reports

resuming sessions, Resuming sessions, Session resumption

S

safe renegotiation, Safe renegotiation

server name indication, Server name indication

session resumption, Resuming sessions, Session resumption

session tickets, Session tickets

Smart card example, Using a smart card with TLS

smart cards, Smart cards and HSMs

SRP authentication, Authentication using SRP

srptool, Invoking srptool

srptool usage, Invoking srptool

srptool-create-conf, Invoking srptool

srptool-debug, Invoking srptool

srptool-index, Invoking srptool

srptool-passwd, Invoking srptool

srptool-passwd-conf, Invoking srptool

srptool-salt, Invoking srptool

srptool-username, Invoking srptool

srptool-verify, Invoking srptool

SSH-style authentication, Verifying a certificate using trust on first use authentication

SSL 2, On SSL 2 and older protocols

symmetric cryptography, Symmetric cryptography

symmetric encryption algorithms, Encryption algorithms used in the record layer

T

thread safety, Thread safety

tickets, Session tickets

TLS extensions, TLS extensions, Maximum fragment length negotiation, Server name indication, Session tickets

TLS layers, TLS layers

transport layer, The transport layer

transport protocol, The transport layer

Trust on first use, Verifying a certificate using trust on first use authentication

V

verifying certificate paths, Verifying X.509 certificate paths, Verifying a certificate in the context of TLS session, Verifying a certificate using trust on first use authentication

X

X.509 certificates, X.509 certificates

X.509 distinguished name, X.509 distinguished names

X.509 Functions, X.509 certificate API

Chapter . Concept Index

Index

A

abstract types, Abstract key types

alert protocol, The TLS alert protocol

anonymous authentication, Anonymous authentication

API reference, API reference

B

bad_record_mac, On record padding

C

callback functions, Callback functions

certificate authentication, Certificate authentication, More on certificate authentication

certificate requests, PKCS #10 certificate requests

certificate revocation lists, PKIX certificate revocation lists

certificate status, OCSP certificate status checking

certtool, Invoking certtool

certtool usage, Invoking certtool

certtool-bits, Invoking certtool

certtool-certificate-info, Invoking certtool

certtool-certificate-pubkey, Invoking certtool

certtool-crl-info, Invoking certtool

certtool-crq-info, Invoking certtool

certtool-debug, Invoking certtool

certtool-dh-info, Invoking certtool

certtool-disable-quick-random, Invoking certtool

certtool-dsa, Invoking certtool

certtool-ecc, Invoking certtool

certtool-generate-certificate, Invoking certtool

certtool-generate-crl, Invoking certtool

certtool-generate-dh-params, Invoking certtool

certtool-generate-privkey, Invoking certtool

certtool-generate-proxy, Invoking certtool

certtool-generate-request, Invoking certtool

certtool-generate-self-signed, Invoking certtool

certtool-get-dh-params, Invoking certtool

certtool-hash, Invoking certtool

certtool-inder, Invoking certtool

certtool-infile, Invoking certtool

certtool-inraw, Invoking certtool

certtool-key-info, Invoking certtool

certtool-load-ca-certificate, Invoking certtool

certtool-load-ca-privkey, Invoking certtool

certtool-load-certificate, Invoking certtool

certtool-load-privkey, Invoking certtool

certtool-load-pubkey, Invoking certtool

certtool-load-request, Invoking certtool

certtool-no-crq-extensions, Invoking certtool

certtool-outder, Invoking certtool

certtool-outfile, Invoking certtool

certtool-outraw, Invoking certtool

certtool-p12-info, Invoking certtool

certtool-p7-info, Invoking certtool

certtool-password, Invoking certtool

certtool-pgp-certificate-info, Invoking certtool

certtool-pgp-key-info, Invoking certtool

certtool-pgp-ring-info, Invoking certtool

certtool-pkcs-cipher, Invoking certtool

certtool-pkcs8, Invoking certtool

certtool-pubkey-info, Invoking certtool

certtool-rsa, Invoking certtool

certtool-sec-param, Invoking certtool

certtool-smime-to-p7, Invoking certtool

certtool-template, Invoking certtool

certtool-to-p12, Invoking certtool

certtool-to-p8, Invoking certtool

certtool-update-certificate, Invoking certtool

certtool-v1, Invoking certtool

certtool-verify, Invoking certtool

certtool-verify-chain, Invoking certtool

certtool-verify-crl, Invoking certtool

channel bindings, Channel bindings

ciphersuites, Supported Ciphersuites

client certificate authentication, Client authentication

compression algorithms, Compression algorithms used in the record layer

contributing, Contributing

CRL, PKIX certificate revocation lists

D

digital signatures, Digital signatures

download, Downloading and installing

E

Encrypted keys, Managing encrypted keys

error codes, Error Codes and Descriptions

example programs, GnuTLS application examples

examples, GnuTLS application examples

exporting keying material, Keying material exporters

F

FDL, GNU Free Documentation License, Copying Information

G

generating parameters, Parameter generation

GnuTLS client, Invoking gnutls-cli

GnuTLS debug client, Invoking gnutls-cli-debug

GnuTLS OCSP tool, Invoking ocsptool

GnuTLS PKCS #11 tool, Invoking certtool, Invoking p11tool

GnuTLS PSK tool, Invoking psktool

GnuTLS server, Invoking gnutls-serv

GnuTLS SRP tool, Invoking srptool

gnutls-cli, Invoking gnutls-cli

gnutls-cli usage, Invoking gnutls-cli

gnutls-cli-benchmark-ciphers, Invoking gnutls-cli

gnutls-cli-benchmark-soft-ciphers, Invoking gnutls-cli

gnutls-cli-benchmark-tls, Invoking gnutls-cli

gnutls-cli-crlf, Invoking gnutls-cli

gnutls-cli-debug, Invoking gnutls-cli, Invoking gnutls-cli-debug

gnutls-cli-debug usage, Invoking gnutls-cli-debug

gnutls-cli-debug-debug, Invoking gnutls-cli-debug

gnutls-cli-debug-port, Invoking gnutls-cli-debug

gnutls-cli-debug-verbose, Invoking gnutls-cli-debug

gnutls-cli-disable-extensions, Invoking gnutls-cli

gnutls-cli-fingerprint, Invoking gnutls-cli

gnutls-cli-insecure, Invoking gnutls-cli

gnutls-cli-list, Invoking gnutls-cli

gnutls-cli-mtu, Invoking gnutls-cli

gnutls-cli-noticket, Invoking gnutls-cli

gnutls-cli-ocsp, Invoking gnutls-cli

gnutls-cli-pgpcertfile, Invoking gnutls-cli

gnutls-cli-pgpkeyfile, Invoking gnutls-cli

gnutls-cli-pgpkeyring, Invoking gnutls-cli

gnutls-cli-pgpsubkey, Invoking gnutls-cli

gnutls-cli-port, Invoking gnutls-cli

gnutls-cli-print-cert, Invoking gnutls-cli

gnutls-cli-priority, Invoking gnutls-cli

gnutls-cli-pskkey, Invoking gnutls-cli

gnutls-cli-pskusername, Invoking gnutls-cli

gnutls-cli-recordsize, Invoking gnutls-cli

gnutls-cli-rehandshake, Invoking gnutls-cli

gnutls-cli-resume, Invoking gnutls-cli

gnutls-cli-srppasswd, Invoking gnutls-cli

gnutls-cli-srpusername, Invoking gnutls-cli

gnutls-cli-starttls, Invoking gnutls-cli

gnutls-cli-tofu, Invoking gnutls-cli

gnutls-cli-udp, Invoking gnutls-cli

gnutls-cli-verbose, Invoking gnutls-cli

gnutls-cli-x509cafile, Invoking gnutls-cli

gnutls-cli-x509certfile, Invoking gnutls-cli

gnutls-cli-x509crlfile, Invoking gnutls-cli

gnutls-cli-x509fmtder, Invoking gnutls-cli

gnutls-cli-x509keyfile, Invoking gnutls-cli

gnutls-serv, Invoking gnutls-serv

gnutls-serv usage, Invoking gnutls-serv

gnutls-serv-debug, Invoking gnutls-serv

gnutls-serv-dhparams, Invoking gnutls-serv

gnutls-serv-disable-client-cert, Invoking gnutls-serv

gnutls-serv-echo, Invoking gnutls-serv

gnutls-serv-generate, Invoking gnutls-serv

gnutls-serv-http, Invoking gnutls-serv

gnutls-serv-list, Invoking gnutls-serv

gnutls-serv-mtu, Invoking gnutls-serv

gnutls-serv-nodb, Invoking gnutls-serv

gnutls-serv-noticket, Invoking gnutls-serv

gnutls-serv-pgpcertfile, Invoking gnutls-serv

gnutls-serv-pgpkeyfile, Invoking gnutls-serv

gnutls-serv-pgpkeyring, Invoking gnutls-serv

gnutls-serv-pgpsubkey, Invoking gnutls-serv

gnutls-serv-port, Invoking gnutls-serv

gnutls-serv-priority, Invoking gnutls-serv

gnutls-serv-pskhint, Invoking gnutls-serv

gnutls-serv-pskpasswd, Invoking gnutls-serv

gnutls-serv-quiet, Invoking gnutls-serv

gnutls-serv-require-client-cert, Invoking gnutls-serv

gnutls-serv-srppasswd, Invoking gnutls-serv

gnutls-serv-srppasswdconf, Invoking gnutls-serv

gnutls-serv-udp, Invoking gnutls-serv

gnutls-serv-x509cafile, Invoking gnutls-serv

gnutls-serv-x509certfile, Invoking gnutls-serv

gnutls-serv-x509crlfile, Invoking gnutls-serv

gnutls-serv-x509dsacertfile, Invoking gnutls-serv

gnutls-serv-x509dsakeyfile, Invoking gnutls-serv

gnutls-serv-x509ecccertfile, Invoking gnutls-serv

gnutls-serv-x509ecckeyfile, Invoking gnutls-serv

gnutls-serv-x509fmtder, Invoking gnutls-serv

gnutls-serv-x509keyfile, Invoking gnutls-serv

gnutls_alert_get, Core TLS API

gnutls_alert_get_name, Core TLS API

gnutls_alert_get_strname, Core TLS API

gnutls_alert_send, Core TLS API

gnutls_alert_send_appropriate, Core TLS API

gnutls_anon_allocate_client_credentials, Core TLS API

gnutls_anon_allocate_server_credentials, Core TLS API

gnutls_anon_free_client_credentials, Core TLS API

gnutls_anon_free_server_credentials, Core TLS API

gnutls_anon_set_params_function, Core TLS API

gnutls_anon_set_server_dh_params, Core TLS API

gnutls_anon_set_server_params_function, Core TLS API

gnutls_auth_client_get_type, Core TLS API

gnutls_auth_get_type, Core TLS API

gnutls_auth_server_get_type, Core TLS API

gnutls_bye, Core TLS API

gnutls_certificate_activation_time_peers, Core TLS API

gnutls_certificate_allocate_credentials, Core TLS API

gnutls_certificate_client_get_request_status, Core TLS API

gnutls_certificate_expiration_time_peers, Core TLS API

gnutls_certificate_free_cas, Core TLS API

gnutls_certificate_free_ca_names, Core TLS API

gnutls_certificate_free_credentials, Core TLS API

gnutls_certificate_free_crls, Core TLS API

gnutls_certificate_free_keys, Core TLS API

gnutls_certificate_get_issuer, Core TLS API

gnutls_certificate_get_ours, Core TLS API

gnutls_certificate_get_peers, Core TLS API

gnutls_certificate_send_x509_rdn_sequence, Core TLS API

gnutls_certificate_server_set_request, Core TLS API

gnutls_certificate_set_dh_params, Core TLS API

gnutls_certificate_set_key, Abstract key API

gnutls_certificate_set_openpgp_key, OpenPGP API

gnutls_certificate_set_openpgp_keyring_file, OpenPGP API

gnutls_certificate_set_openpgp_keyring_mem, OpenPGP API

gnutls_certificate_set_openpgp_key_file, OpenPGP API

gnutls_certificate_set_openpgp_key_file2, OpenPGP API

gnutls_certificate_set_openpgp_key_mem, OpenPGP API

gnutls_certificate_set_openpgp_key_mem2, OpenPGP API

gnutls_certificate_set_params_function, Core TLS API

gnutls_certificate_set_retrieve_function, Core TLS API

gnutls_certificate_set_retrieve_function2, Abstract key API

gnutls_certificate_set_rsa_export_params, Compatibility API

gnutls_certificate_set_verify_flags, Core TLS API

gnutls_certificate_set_verify_function, Core TLS API

gnutls_certificate_set_verify_limits, Core TLS API

gnutls_certificate_set_x509_crl, Core TLS API

gnutls_certificate_set_x509_crl_file, Core TLS API

gnutls_certificate_set_x509_crl_mem, Core TLS API

gnutls_certificate_set_x509_key, Core TLS API

gnutls_certificate_set_x509_key_file, Core TLS API

gnutls_certificate_set_x509_key_mem, Core TLS API

gnutls_certificate_set_x509_simple_pkcs12_file, Core TLS API

gnutls_certificate_set_x509_simple_pkcs12_mem, Core TLS API

gnutls_certificate_set_x509_trust, Core TLS API

gnutls_certificate_set_x509_trust_file, Core TLS API

gnutls_certificate_set_x509_trust_mem, Core TLS API

gnutls_certificate_type_get, Core TLS API

gnutls_certificate_type_get_id, Core TLS API

gnutls_certificate_type_get_name, Core TLS API

gnutls_certificate_type_list, Core TLS API

gnutls_certificate_type_set_priority, Compatibility API

gnutls_certificate_verify_flags, Verifying a certificate in the context of TLS session, Verifying a certificate using trust on first use authentication

gnutls_certificate_verify_peers2, Core TLS API

gnutls_check_version, Core TLS API

gnutls_cipher_add_auth, Cryptographic API

gnutls_cipher_decrypt, Cryptographic API

gnutls_cipher_decrypt2, Cryptographic API

gnutls_cipher_deinit, Cryptographic API

gnutls_cipher_encrypt, Cryptographic API

gnutls_cipher_encrypt2, Cryptographic API

gnutls_cipher_get, Core TLS API

gnutls_cipher_get_block_size, Cryptographic API

gnutls_cipher_get_id, Core TLS API

gnutls_cipher_get_key_size, Core TLS API

gnutls_cipher_get_name, Core TLS API

gnutls_cipher_init, Cryptographic API

gnutls_cipher_list, Core TLS API

gnutls_cipher_set_iv, Cryptographic API

gnutls_cipher_set_priority, Compatibility API

gnutls_cipher_suite_get_name, Core TLS API

gnutls_cipher_suite_info, Core TLS API

gnutls_cipher_tag, Cryptographic API

gnutls_compression_get, Core TLS API

gnutls_compression_get_id, Core TLS API

gnutls_compression_get_name, Core TLS API

gnutls_compression_list, Core TLS API

gnutls_compression_set_priority, Compatibility API

gnutls_credentials_clear, Core TLS API

gnutls_credentials_set, Core TLS API

gnutls_db_check_entry, Core TLS API

gnutls_db_get_ptr, Core TLS API

gnutls_db_remove_session, Core TLS API

gnutls_db_set_cache_expiration, Core TLS API

gnutls_db_set_ptr, Core TLS API

gnutls_db_set_remove_function, Core TLS API

gnutls_db_set_retrieve_function, Core TLS API

gnutls_db_set_store_function, Core TLS API

gnutls_deinit, Core TLS API

gnutls_dh_get_group, Core TLS API

gnutls_dh_get_peers_public_bits, Core TLS API

gnutls_dh_get_prime_bits, Core TLS API

gnutls_dh_get_pubkey, Core TLS API

gnutls_dh_get_secret_bits, Core TLS API

gnutls_dh_params_cpy, Core TLS API

gnutls_dh_params_deinit, Core TLS API

gnutls_dh_params_export_pkcs3, Core TLS API

gnutls_dh_params_export_raw, Core TLS API

gnutls_dh_params_generate2, Core TLS API

gnutls_dh_params_import_pkcs3, Core TLS API

gnutls_dh_params_import_raw, Core TLS API

gnutls_dh_params_init, Core TLS API

gnutls_dh_set_prime_bits, Core TLS API

gnutls_dtls_cookie_send, Datagram TLS API

gnutls_dtls_cookie_verify, Datagram TLS API

gnutls_dtls_get_data_mtu, Datagram TLS API

gnutls_dtls_get_mtu, Datagram TLS API

gnutls_dtls_get_timeout, Datagram TLS API

gnutls_dtls_prestate_set, Datagram TLS API

gnutls_dtls_set_mtu, Datagram TLS API

gnutls_dtls_set_timeouts, Datagram TLS API

gnutls_ecc_curve_get, Core TLS API

gnutls_ecc_curve_get_name, Core TLS API

gnutls_ecc_curve_get_size, Core TLS API

gnutls_ecc_curve_list, Core TLS API

gnutls_error_is_fatal, Core TLS API

gnutls_error_to_alert, Core TLS API

gnutls_fingerprint, Core TLS API

gnutls_global_deinit, Core TLS API

gnutls_global_init, Core TLS API

gnutls_global_set_audit_log_function, Core TLS API

gnutls_global_set_log_function, Core TLS API

gnutls_global_set_log_level, Core TLS API

gnutls_global_set_mem_functions, Core TLS API

gnutls_global_set_mutex, Core TLS API

gnutls_global_set_time_function, Core TLS API

gnutls_handshake, Core TLS API

gnutls_handshake_get_last_in, Core TLS API

gnutls_handshake_get_last_out, Core TLS API

gnutls_handshake_set_max_packet_length, Core TLS API

gnutls_handshake_set_post_client_hello_function, Core TLS API

gnutls_handshake_set_private_extensions, Core TLS API

gnutls_hash, Cryptographic API

gnutls_hash_deinit, Cryptographic API

gnutls_hash_fast, Cryptographic API

gnutls_hash_get_len, Cryptographic API

gnutls_hash_init, Cryptographic API

gnutls_hash_output, Cryptographic API

gnutls_hex2bin, Core TLS API

gnutls_hex_decode, Core TLS API

gnutls_hex_encode, Core TLS API

gnutls_hmac, Cryptographic API

gnutls_hmac_deinit, Cryptographic API

gnutls_hmac_fast, Cryptographic API

gnutls_hmac_get_len, Cryptographic API

gnutls_hmac_init, Cryptographic API

gnutls_hmac_output, Cryptographic API

gnutls_init, Core TLS API

gnutls_key_generate, Core TLS API

gnutls_kx_get, Core TLS API

gnutls_kx_get_id, Core TLS API

gnutls_kx_get_name, Core TLS API

gnutls_kx_list, Core TLS API

gnutls_kx_set_priority, Compatibility API

gnutls_mac_get, Core TLS API

gnutls_mac_get_id, Core TLS API

gnutls_mac_get_key_size, Core TLS API

gnutls_mac_get_name, Core TLS API

gnutls_mac_list, Core TLS API

gnutls_mac_set_priority, Compatibility API

gnutls_ocsp_req_add_cert, OCSP API

gnutls_ocsp_req_add_cert_id, OCSP API

gnutls_ocsp_req_deinit, OCSP API

gnutls_ocsp_req_export, OCSP API

gnutls_ocsp_req_get_cert_id, OCSP API

gnutls_ocsp_req_get_extension, OCSP API

gnutls_ocsp_req_get_nonce, OCSP API

gnutls_ocsp_req_get_version, OCSP API

gnutls_ocsp_req_import, OCSP API

gnutls_ocsp_req_init, OCSP API

gnutls_ocsp_req_print, OCSP API

gnutls_ocsp_req_randomize_nonce, OCSP API

gnutls_ocsp_req_set_extension, OCSP API

gnutls_ocsp_req_set_nonce, OCSP API

gnutls_ocsp_resp_deinit, OCSP API

gnutls_ocsp_resp_export, OCSP API

gnutls_ocsp_resp_get_certs, OCSP API

gnutls_ocsp_resp_get_extension, OCSP API

gnutls_ocsp_resp_get_nonce, OCSP API

gnutls_ocsp_resp_get_produced, OCSP API

gnutls_ocsp_resp_get_responder, OCSP API

gnutls_ocsp_resp_get_response, OCSP API

gnutls_ocsp_resp_get_signature, OCSP API

gnutls_ocsp_resp_get_signature_algorithm, OCSP API

gnutls_ocsp_resp_get_single, OCSP API

gnutls_ocsp_resp_get_status, OCSP API

gnutls_ocsp_resp_get_version, OCSP API

gnutls_ocsp_resp_import, OCSP API

gnutls_ocsp_resp_init, OCSP API

gnutls_ocsp_resp_print, OCSP API

gnutls_ocsp_resp_verify, OCSP API

gnutls_ocsp_resp_verify_direct, OCSP API

gnutls_openpgp_crt_check_hostname, OpenPGP API

gnutls_openpgp_crt_deinit, OpenPGP API

gnutls_openpgp_crt_export, OpenPGP API

gnutls_openpgp_crt_get_auth_subkey, OpenPGP API

gnutls_openpgp_crt_get_creation_time, OpenPGP API

gnutls_openpgp_crt_get_expiration_time, OpenPGP API

gnutls_openpgp_crt_get_fingerprint, OpenPGP API

gnutls_openpgp_crt_get_key_id, OpenPGP API

gnutls_openpgp_crt_get_key_usage, OpenPGP API

gnutls_openpgp_crt_get_name, OpenPGP API

gnutls_openpgp_crt_get_pk_algorithm, OpenPGP API

gnutls_openpgp_crt_get_pk_dsa_raw, OpenPGP API

gnutls_openpgp_crt_get_pk_rsa_raw, OpenPGP API

gnutls_openpgp_crt_get_preferred_key_id, OpenPGP API

gnutls_openpgp_crt_get_revoked_status, OpenPGP API

gnutls_openpgp_crt_get_subkey_count, OpenPGP API

gnutls_openpgp_crt_get_subkey_creation_time, OpenPGP API

gnutls_openpgp_crt_get_subkey_expiration_time, OpenPGP API

gnutls_openpgp_crt_get_subkey_fingerprint, OpenPGP API

gnutls_openpgp_crt_get_subkey_id, OpenPGP API

gnutls_openpgp_crt_get_subkey_idx, OpenPGP API

gnutls_openpgp_crt_get_subkey_pk_algorithm, OpenPGP API

gnutls_openpgp_crt_get_subkey_pk_dsa_raw, OpenPGP API

gnutls_openpgp_crt_get_subkey_pk_rsa_raw, OpenPGP API

gnutls_openpgp_crt_get_subkey_revoked_status, OpenPGP API

gnutls_openpgp_crt_get_subkey_usage, OpenPGP API

gnutls_openpgp_crt_get_version, OpenPGP API

gnutls_openpgp_crt_import, OpenPGP API

gnutls_openpgp_crt_init, OpenPGP API

gnutls_openpgp_crt_print, OpenPGP API

gnutls_openpgp_crt_set_preferred_key_id, OpenPGP API

gnutls_openpgp_crt_verify_ring, OpenPGP API

gnutls_openpgp_crt_verify_self, OpenPGP API

gnutls_openpgp_keyring_check_id, OpenPGP API

gnutls_openpgp_keyring_deinit, OpenPGP API

gnutls_openpgp_keyring_get_crt, OpenPGP API

gnutls_openpgp_keyring_get_crt_count, OpenPGP API

gnutls_openpgp_keyring_import, OpenPGP API

gnutls_openpgp_keyring_init, OpenPGP API

gnutls_openpgp_privkey_deinit, OpenPGP API

gnutls_openpgp_privkey_export, OpenPGP API

gnutls_openpgp_privkey_export_dsa_raw, OpenPGP API

gnutls_openpgp_privkey_export_rsa_raw, OpenPGP API

gnutls_openpgp_privkey_export_subkey_dsa_raw, OpenPGP API

gnutls_openpgp_privkey_export_subkey_rsa_raw, OpenPGP API

gnutls_openpgp_privkey_get_fingerprint, OpenPGP API

gnutls_openpgp_privkey_get_key_id, OpenPGP API

gnutls_openpgp_privkey_get_pk_algorithm, OpenPGP API

gnutls_openpgp_privkey_get_preferred_key_id, OpenPGP API

gnutls_openpgp_privkey_get_revoked_status, OpenPGP API

gnutls_openpgp_privkey_get_subkey_count, OpenPGP API

gnutls_openpgp_privkey_get_subkey_creation_time, OpenPGP API

gnutls_openpgp_privkey_get_subkey_fingerprint, OpenPGP API

gnutls_openpgp_privkey_get_subkey_id, OpenPGP API

gnutls_openpgp_privkey_get_subkey_idx, OpenPGP API

gnutls_openpgp_privkey_get_subkey_pk_algorithm, OpenPGP API

gnutls_openpgp_privkey_get_subkey_revoked_status, OpenPGP API

gnutls_openpgp_privkey_import, OpenPGP API

gnutls_openpgp_privkey_init, OpenPGP API

gnutls_openpgp_privkey_sec_param, OpenPGP API

gnutls_openpgp_privkey_set_preferred_key_id, OpenPGP API

gnutls_openpgp_privkey_sign_hash, Compatibility API

gnutls_openpgp_send_cert, Core TLS API

gnutls_openpgp_set_recv_key_function, OpenPGP API

gnutls_pcert_deinit, Abstract key API

gnutls_pcert_import_openpgp, Abstract key API

gnutls_pcert_import_openpgp_raw, Abstract key API

gnutls_pcert_import_x509, Abstract key API

gnutls_pcert_import_x509_raw, Abstract key API

gnutls_pcert_list_import_x509_raw, Abstract key API

gnutls_pem_base64_decode, Core TLS API

gnutls_pem_base64_decode_alloc, Core TLS API

gnutls_pem_base64_encode, Core TLS API

gnutls_pem_base64_encode_alloc, Core TLS API

gnutls_perror, Core TLS API

gnutls_pkcs11_add_provider, Hardware token via PKCS 11 API

gnutls_pkcs11_copy_secret_key, Hardware token via PKCS 11 API

gnutls_pkcs11_copy_x509_crt, Hardware token via PKCS 11 API

gnutls_pkcs11_copy_x509_privkey, Hardware token via PKCS 11 API

gnutls_pkcs11_deinit, Hardware token via PKCS 11 API

gnutls_pkcs11_delete_url, Hardware token via PKCS 11 API

gnutls_pkcs11_init, Hardware token via PKCS 11 API

gnutls_pkcs11_obj_deinit, Hardware token via PKCS 11 API

gnutls_pkcs11_obj_export, Hardware token via PKCS 11 API

gnutls_pkcs11_obj_export_url, Hardware token via PKCS 11 API

gnutls_pkcs11_obj_get_info, Hardware token via PKCS 11 API

gnutls_pkcs11_obj_get_type, Hardware token via PKCS 11 API

gnutls_pkcs11_obj_import_url, Hardware token via PKCS 11 API

gnutls_pkcs11_obj_init, Hardware token via PKCS 11 API

gnutls_pkcs11_obj_list_import_url, Hardware token via PKCS 11 API

gnutls_pkcs11_privkey_deinit, Hardware token via PKCS 11 API

gnutls_pkcs11_privkey_export_url, Hardware token via PKCS 11 API

gnutls_pkcs11_privkey_generate, Hardware token via PKCS 11 API

gnutls_pkcs11_privkey_get_info, Hardware token via PKCS 11 API

gnutls_pkcs11_privkey_get_pk_algorithm, Hardware token via PKCS 11 API

gnutls_pkcs11_privkey_import_url, Hardware token via PKCS 11 API

gnutls_pkcs11_privkey_init, Hardware token via PKCS 11 API

gnutls_pkcs11_reinit, Hardware token via PKCS 11 API

gnutls_pkcs11_set_pin_function, Hardware token via PKCS 11 API

gnutls_pkcs11_set_token_function, Hardware token via PKCS 11 API

gnutls_pkcs11_token_get_flags, Hardware token via PKCS 11 API

gnutls_pkcs11_token_get_info, Hardware token via PKCS 11 API

gnutls_pkcs11_token_get_mechanism, Hardware token via PKCS 11 API

gnutls_pkcs11_token_get_url, Hardware token via PKCS 11 API

gnutls_pkcs11_token_init, Hardware token via PKCS 11 API

gnutls_pkcs11_token_set_pin, Hardware token via PKCS 11 API

gnutls_pkcs11_type_get_name, Hardware token via PKCS 11 API

gnutls_pkcs12_bag_decrypt, PKCS 12 API

gnutls_pkcs12_bag_deinit, PKCS 12 API

gnutls_pkcs12_bag_encrypt, PKCS 12 API

gnutls_pkcs12_bag_get_count, PKCS 12 API

gnutls_pkcs12_bag_get_data, PKCS 12 API

gnutls_pkcs12_bag_get_friendly_name, PKCS 12 API

gnutls_pkcs12_bag_get_key_id, PKCS 12 API

gnutls_pkcs12_bag_get_type, PKCS 12 API

gnutls_pkcs12_bag_init, PKCS 12 API

gnutls_pkcs12_bag_set_crl, PKCS 12 API

gnutls_pkcs12_bag_set_crt, PKCS 12 API

gnutls_pkcs12_bag_set_data, PKCS 12 API

gnutls_pkcs12_bag_set_friendly_name, PKCS 12 API

gnutls_pkcs12_bag_set_key_id, PKCS 12 API

gnutls_pkcs12_deinit, PKCS 12 API

gnutls_pkcs12_export, PKCS 12 API

gnutls_pkcs12_generate_mac, PKCS 12 API

gnutls_pkcs12_get_bag, PKCS 12 API

gnutls_pkcs12_import, PKCS 12 API

gnutls_pkcs12_init, PKCS 12 API

gnutls_pkcs12_set_bag, PKCS 12 API

gnutls_pkcs12_verify_mac, PKCS 12 API

gnutls_pkcs7_deinit, X.509 certificate API

gnutls_pkcs7_delete_crl, X.509 certificate API

gnutls_pkcs7_delete_crt, X.509 certificate API

gnutls_pkcs7_export, X.509 certificate API

gnutls_pkcs7_get_crl_count, X.509 certificate API

gnutls_pkcs7_get_crl_raw, X.509 certificate API

gnutls_pkcs7_get_crt_count, X.509 certificate API

gnutls_pkcs7_get_crt_raw, X.509 certificate API

gnutls_pkcs7_import, X.509 certificate API

gnutls_pkcs7_init, X.509 certificate API

gnutls_pkcs7_set_crl, X.509 certificate API

gnutls_pkcs7_set_crl_raw, X.509 certificate API

gnutls_pkcs7_set_crt, X.509 certificate API

gnutls_pkcs7_set_crt_raw, X.509 certificate API

gnutls_pk_algorithm_get_name, Core TLS API

gnutls_pk_bits_to_sec_param, Core TLS API

gnutls_pk_get_id, Core TLS API

gnutls_pk_get_name, Core TLS API

gnutls_pk_list, Core TLS API

gnutls_prf, Core TLS API

gnutls_prf_raw, Core TLS API

gnutls_priority_certificate_type_list, Core TLS API

gnutls_priority_compression_list, Core TLS API

gnutls_priority_deinit, Core TLS API

gnutls_priority_ecc_curve_list, Core TLS API

gnutls_priority_get_cipher_suite_index, Core TLS API

gnutls_priority_init, Core TLS API

gnutls_priority_protocol_list, Core TLS API

gnutls_priority_set, Core TLS API

gnutls_priority_set_direct, Core TLS API

gnutls_priority_sign_list, Core TLS API

gnutls_privkey_decrypt_data, Abstract key API

gnutls_privkey_deinit, Abstract key API

gnutls_privkey_get_pk_algorithm, Abstract key API

gnutls_privkey_get_type, Abstract key API

gnutls_privkey_import_ext, Abstract key API

gnutls_privkey_import_openpgp, Abstract key API

gnutls_privkey_import_pkcs11, Abstract key API

gnutls_privkey_import_x509, Abstract key API

gnutls_privkey_init, Abstract key API

gnutls_privkey_sign_data, Abstract key API

gnutls_privkey_sign_hash, Abstract key API

gnutls_protocol_get_id, Core TLS API

gnutls_protocol_get_name, Core TLS API

gnutls_protocol_get_version, Core TLS API

gnutls_protocol_list, Core TLS API

gnutls_protocol_set_priority, Compatibility API

gnutls_psk_allocate_client_credentials, Core TLS API

gnutls_psk_allocate_server_credentials, Core TLS API

gnutls_psk_client_get_hint, Core TLS API

gnutls_psk_free_client_credentials, Core TLS API

gnutls_psk_free_server_credentials, Core TLS API

gnutls_psk_server_get_username, Core TLS API

gnutls_psk_set_client_credentials, Core TLS API

gnutls_psk_set_client_credentials_function, Core TLS API

gnutls_psk_set_params_function, Core TLS API

gnutls_psk_set_server_credentials_file, Core TLS API

gnutls_psk_set_server_credentials_function, Core TLS API

gnutls_psk_set_server_credentials_hint, Core TLS API

gnutls_psk_set_server_dh_params, Core TLS API

gnutls_psk_set_server_params_function, Core TLS API

gnutls_pubkey_deinit, Abstract key API

gnutls_pubkey_encrypt_data, Abstract key API

gnutls_pubkey_export, Abstract key API

gnutls_pubkey_get_key_id, Abstract key API

gnutls_pubkey_get_key_usage, Abstract key API

gnutls_pubkey_get_openpgp_key_id, Abstract key API

gnutls_pubkey_get_pk_algorithm, Abstract key API

gnutls_pubkey_get_pk_dsa_raw, Abstract key API

gnutls_pubkey_get_pk_ecc_raw, Abstract key API

gnutls_pubkey_get_pk_ecc_x962, Abstract key API

gnutls_pubkey_get_pk_rsa_raw, Abstract key API

gnutls_pubkey_get_preferred_hash_algorithm, Abstract key API

gnutls_pubkey_get_verify_algorithm, Abstract key API

gnutls_pubkey_import, Abstract key API

gnutls_pubkey_import_dsa_raw, Abstract key API

gnutls_pubkey_import_ecc_raw, Abstract key API

gnutls_pubkey_import_ecc_x962, Abstract key API

gnutls_pubkey_import_openpgp, Abstract key API

gnutls_pubkey_import_pkcs11, Abstract key API

gnutls_pubkey_import_pkcs11_url, Abstract key API

gnutls_pubkey_import_privkey, Abstract key API

gnutls_pubkey_import_rsa_raw, Abstract key API

gnutls_pubkey_import_x509, Abstract key API

gnutls_pubkey_init, Abstract key API

gnutls_pubkey_set_key_usage, Abstract key API

gnutls_pubkey_verify_data, Abstract key API

gnutls_pubkey_verify_data2, Abstract key API

gnutls_pubkey_verify_hash, Abstract key API

gnutls_random_art, Core TLS API

gnutls_record_check_pending, Core TLS API

gnutls_record_disable_padding, Core TLS API

gnutls_record_get_direction, Core TLS API

gnutls_record_get_discarded, Datagram TLS API

gnutls_record_get_max_size, Core TLS API

gnutls_record_recv, Core TLS API

gnutls_record_recv_seq, Core TLS API

gnutls_record_send, Core TLS API

gnutls_record_set_max_size, Core TLS API

gnutls_rehandshake, Core TLS API

gnutls_rnd, Cryptographic API

gnutls_rsa_export_get_modulus_bits, Compatibility API

gnutls_rsa_export_get_pubkey, Compatibility API

gnutls_rsa_params_cpy, Compatibility API

gnutls_rsa_params_deinit, Compatibility API

gnutls_rsa_params_export_pkcs1, Compatibility API

gnutls_rsa_params_export_raw, Compatibility API

gnutls_rsa_params_generate2, Compatibility API

gnutls_rsa_params_import_pkcs1, Compatibility API

gnutls_rsa_params_import_raw, Compatibility API

gnutls_rsa_params_init, Compatibility API

gnutls_safe_renegotiation_status, Core TLS API

gnutls_sec_param_get_name, Core TLS API

gnutls_sec_param_to_pk_bits, Core TLS API

gnutls_server_name_get, Core TLS API

gnutls_server_name_set, Core TLS API

gnutls_session_channel_binding, Core TLS API

gnutls_session_enable_compatibility_mode, Core TLS API

gnutls_session_get_data, Core TLS API

gnutls_session_get_data2, Core TLS API

gnutls_session_get_id, Core TLS API

gnutls_session_get_ptr, Core TLS API

gnutls_session_get_random, Core TLS API

gnutls_session_is_resumed, Core TLS API

gnutls_session_resumption_requested, Core TLS API

gnutls_session_set_data, Core TLS API

gnutls_session_set_ptr, Core TLS API

gnutls_session_ticket_enable_client, Core TLS API

gnutls_session_ticket_enable_server, Core TLS API

gnutls_session_ticket_key_generate, Core TLS API

gnutls_set_default_export_priority, Compatibility API

gnutls_set_default_priority, Core TLS API

gnutls_sign_algorithm_get_requested, Core TLS API

gnutls_sign_callback_get, Compatibility API

gnutls_sign_callback_set, Compatibility API

gnutls_sign_get_id, Core TLS API

gnutls_sign_get_name, Core TLS API

gnutls_sign_list, Core TLS API

gnutls_srp_allocate_client_credentials, Core TLS API

gnutls_srp_allocate_server_credentials, Core TLS API

gnutls_srp_base64_decode, Core TLS API

gnutls_srp_base64_decode_alloc, Core TLS API

gnutls_srp_base64_encode, Core TLS API

gnutls_srp_base64_encode_alloc, Core TLS API

gnutls_srp_free_client_credentials, Core TLS API

gnutls_srp_free_server_credentials, Core TLS API

gnutls_srp_server_get_username, Core TLS API

gnutls_srp_set_client_credentials, Core TLS API

gnutls_srp_set_client_credentials_function, Core TLS API

gnutls_srp_set_prime_bits, Core TLS API

gnutls_srp_set_server_credentials_file, Core TLS API

gnutls_srp_set_server_credentials_function, Core TLS API

gnutls_srp_verifier, Core TLS API

gnutls_store_commitment, Core TLS API

gnutls_store_pubkey, Core TLS API

gnutls_strerror, Core TLS API

gnutls_strerror_name, Core TLS API

gnutls_supplemental_get_name, Core TLS API

gnutls_tdb_deinit, Core TLS API

gnutls_tdb_init, Core TLS API

gnutls_tdb_set_store_commitment_func, Core TLS API

gnutls_tdb_set_store_func, Core TLS API

gnutls_tdb_set_verify_func, Core TLS API

gnutls_transport_get_ptr, Core TLS API

gnutls_transport_get_ptr2, Core TLS API

gnutls_transport_set_errno, Core TLS API

gnutls_transport_set_errno_function, Core TLS API

gnutls_transport_set_ptr, Core TLS API

gnutls_transport_set_ptr2, Core TLS API

gnutls_transport_set_pull_function, Core TLS API

gnutls_transport_set_pull_timeout_function, Core TLS API

gnutls_transport_set_push_function, Core TLS API

gnutls_transport_set_vec_push_function, Core TLS API

gnutls_verify_stored_pubkey, Core TLS API

gnutls_x509_crl_check_issuer, X.509 certificate API

gnutls_x509_crl_deinit, X.509 certificate API

gnutls_x509_crl_export, X.509 certificate API

gnutls_x509_crl_get_authority_key_gn_serial, X.509 certificate API

gnutls_x509_crl_get_authority_key_id, X.509 certificate API

gnutls_x509_crl_get_crt_count, X.509 certificate API

gnutls_x509_crl_get_crt_serial, X.509 certificate API

gnutls_x509_crl_get_dn_oid, X.509 certificate API

gnutls_x509_crl_get_extension_data, X.509 certificate API

gnutls_x509_crl_get_extension_info, X.509 certificate API

gnutls_x509_crl_get_extension_oid, X.509 certificate API

gnutls_x509_crl_get_issuer_dn, X.509 certificate API

gnutls_x509_crl_get_issuer_dn_by_oid, X.509 certificate API

gnutls_x509_crl_get_next_update, X.509 certificate API

gnutls_x509_crl_get_number, X.509 certificate API

gnutls_x509_crl_get_raw_issuer_dn, X.509 certificate API

gnutls_x509_crl_get_signature, X.509 certificate API

gnutls_x509_crl_get_signature_algorithm, X.509 certificate API

gnutls_x509_crl_get_this_update, X.509 certificate API

gnutls_x509_crl_get_version, X.509 certificate API

gnutls_x509_crl_import, X.509 certificate API

gnutls_x509_crl_init, X.509 certificate API

gnutls_x509_crl_list_import, X.509 certificate API

gnutls_x509_crl_list_import2, X.509 certificate API

gnutls_x509_crl_print, X.509 certificate API

gnutls_x509_crl_privkey_sign, Abstract key API

gnutls_x509_crl_set_authority_key_id, X.509 certificate API

gnutls_x509_crl_set_crt, X.509 certificate API

gnutls_x509_crl_set_crt_serial, X.509 certificate API

gnutls_x509_crl_set_next_update, X.509 certificate API

gnutls_x509_crl_set_number, X.509 certificate API

gnutls_x509_crl_set_this_update, X.509 certificate API

gnutls_x509_crl_set_version, X.509 certificate API

gnutls_x509_crl_sign, Compatibility API

gnutls_x509_crl_sign2, X.509 certificate API

gnutls_x509_crl_verify, X.509 certificate API

gnutls_x509_crq_deinit, X.509 certificate API

gnutls_x509_crq_export, X.509 certificate API

gnutls_x509_crq_get_attribute_by_oid, X.509 certificate API

gnutls_x509_crq_get_attribute_data, X.509 certificate API

gnutls_x509_crq_get_attribute_info, X.509 certificate API

gnutls_x509_crq_get_basic_constraints, X.509 certificate API

gnutls_x509_crq_get_challenge_password, X.509 certificate API

gnutls_x509_crq_get_dn, X.509 certificate API

gnutls_x509_crq_get_dn_by_oid, X.509 certificate API

gnutls_x509_crq_get_dn_oid, X.509 certificate API

gnutls_x509_crq_get_extension_by_oid, X.509 certificate API

gnutls_x509_crq_get_extension_data, X.509 certificate API

gnutls_x509_crq_get_extension_info, X.509 certificate API

gnutls_x509_crq_get_key_id, X.509 certificate API

gnutls_x509_crq_get_key_purpose_oid, X.509 certificate API

gnutls_x509_crq_get_key_rsa_raw, X.509 certificate API

gnutls_x509_crq_get_key_usage, X.509 certificate API

gnutls_x509_crq_get_pk_algorithm, X.509 certificate API

gnutls_x509_crq_get_private_key_usage_period, X.509 certificate API

gnutls_x509_crq_get_subject_alt_name, X.509 certificate API

gnutls_x509_crq_get_subject_alt_othername_oid, X.509 certificate API

gnutls_x509_crq_get_version, X.509 certificate API

gnutls_x509_crq_import, X.509 certificate API

gnutls_x509_crq_init, X.509 certificate API

gnutls_x509_crq_print, X.509 certificate API

gnutls_x509_crq_privkey_sign, Abstract key API

gnutls_x509_crq_set_attribute_by_oid, X.509 certificate API

gnutls_x509_crq_set_basic_constraints, X.509 certificate API

gnutls_x509_crq_set_challenge_password, X.509 certificate API

gnutls_x509_crq_set_dn_by_oid, X.509 certificate API

gnutls_x509_crq_set_key, X.509 certificate API

gnutls_x509_crq_set_key_purpose_oid, X.509 certificate API

gnutls_x509_crq_set_key_rsa_raw, X.509 certificate API

gnutls_x509_crq_set_key_usage, X.509 certificate API

gnutls_x509_crq_set_private_key_usage_period, X.509 certificate API

gnutls_x509_crq_set_pubkey, Abstract key API

gnutls_x509_crq_set_subject_alt_name, X.509 certificate API

gnutls_x509_crq_set_version, X.509 certificate API

gnutls_x509_crq_sign, Compatibility API

gnutls_x509_crq_sign2, X.509 certificate API

gnutls_x509_crq_verify, X.509 certificate API

gnutls_x509_crt_check_hostname, X.509 certificate API

gnutls_x509_crt_check_issuer, X.509 certificate API

gnutls_x509_crt_check_revocation, X.509 certificate API

gnutls_x509_crt_cpy_crl_dist_points, X.509 certificate API

gnutls_x509_crt_deinit, X.509 certificate API

gnutls_x509_crt_export, X.509 certificate API

gnutls_x509_crt_get_activation_time, X.509 certificate API

gnutls_x509_crt_get_authority_info_access, X.509 certificate API

gnutls_x509_crt_get_authority_key_gn_serial, X.509 certificate API

gnutls_x509_crt_get_authority_key_id, X.509 certificate API

gnutls_x509_crt_get_basic_constraints, X.509 certificate API

gnutls_x509_crt_get_ca_status, X.509 certificate API

gnutls_x509_crt_get_crl_dist_points, X.509 certificate API

gnutls_x509_crt_get_dn, X.509 certificate API

gnutls_x509_crt_get_dn_by_oid, X.509 certificate API

gnutls_x509_crt_get_dn_oid, X.509 certificate API

gnutls_x509_crt_get_expiration_time, X.509 certificate API

gnutls_x509_crt_get_extension_by_oid, X.509 certificate API

gnutls_x509_crt_get_extension_data, X.509 certificate API

gnutls_x509_crt_get_extension_info, X.509 certificate API

gnutls_x509_crt_get_extension_oid, X.509 certificate API

gnutls_x509_crt_get_fingerprint, X.509 certificate API

gnutls_x509_crt_get_issuer, X.509 certificate API

gnutls_x509_crt_get_issuer_alt_name, X.509 certificate API

gnutls_x509_crt_get_issuer_alt_name2, X.509 certificate API

gnutls_x509_crt_get_issuer_alt_othername_oid, X.509 certificate API

gnutls_x509_crt_get_issuer_dn, X.509 certificate API

gnutls_x509_crt_get_issuer_dn_by_oid, X.509 certificate API

gnutls_x509_crt_get_issuer_dn_oid, X.509 certificate API

gnutls_x509_crt_get_issuer_unique_id, X.509 certificate API

gnutls_x509_crt_get_key_id, X.509 certificate API

gnutls_x509_crt_get_key_purpose_oid, X.509 certificate API

gnutls_x509_crt_get_key_usage, X.509 certificate API

gnutls_x509_crt_get_pk_algorithm, X.509 certificate API

gnutls_x509_crt_get_pk_dsa_raw, X.509 certificate API

gnutls_x509_crt_get_pk_rsa_raw, X.509 certificate API

gnutls_x509_crt_get_preferred_hash_algorithm, Compatibility API

gnutls_x509_crt_get_private_key_usage_period, X.509 certificate API

gnutls_x509_crt_get_proxy, X.509 certificate API

gnutls_x509_crt_get_raw_dn, X.509 certificate API

gnutls_x509_crt_get_raw_issuer_dn, X.509 certificate API

gnutls_x509_crt_get_serial, X.509 certificate API

gnutls_x509_crt_get_signature, X.509 certificate API

gnutls_x509_crt_get_signature_algorithm, X.509 certificate API

gnutls_x509_crt_get_subject, X.509 certificate API

gnutls_x509_crt_get_subject_alt_name, X.509 certificate API

gnutls_x509_crt_get_subject_alt_name2, X.509 certificate API

gnutls_x509_crt_get_subject_alt_othername_oid, X.509 certificate API

gnutls_x509_crt_get_subject_key_id, X.509 certificate API

gnutls_x509_crt_get_subject_unique_id, X.509 certificate API

gnutls_x509_crt_get_verify_algorithm, Compatibility API

gnutls_x509_crt_get_version, X.509 certificate API

gnutls_x509_crt_import, X.509 certificate API

gnutls_x509_crt_import_pkcs11, Hardware token via PKCS 11 API

gnutls_x509_crt_import_pkcs11_url, Hardware token via PKCS 11 API

gnutls_x509_crt_init, X.509 certificate API

gnutls_x509_crt_list_import, X.509 certificate API

gnutls_x509_crt_list_import2, X.509 certificate API

gnutls_x509_crt_list_import_pkcs11, Hardware token via PKCS 11 API

gnutls_x509_crt_list_verify, X.509 certificate API

gnutls_x509_crt_print, X.509 certificate API

gnutls_x509_crt_privkey_sign, Abstract key API

gnutls_x509_crt_set_activation_time, X.509 certificate API

gnutls_x509_crt_set_authority_info_access, X.509 certificate API

gnutls_x509_crt_set_authority_key_id, X.509 certificate API

gnutls_x509_crt_set_basic_constraints, X.509 certificate API

gnutls_x509_crt_set_ca_status, X.509 certificate API

gnutls_x509_crt_set_crl_dist_points, X.509 certificate API

gnutls_x509_crt_set_crl_dist_points2, X.509 certificate API

gnutls_x509_crt_set_crq, X.509 certificate API

gnutls_x509_crt_set_crq_extensions, X.509 certificate API

gnutls_x509_crt_set_dn_by_oid, X.509 certificate API

gnutls_x509_crt_set_expiration_time, X.509 certificate API

gnutls_x509_crt_set_extension_by_oid, X.509 certificate API

gnutls_x509_crt_set_issuer_dn_by_oid, X.509 certificate API

gnutls_x509_crt_set_key, X.509 certificate API

gnutls_x509_crt_set_key_purpose_oid, X.509 certificate API

gnutls_x509_crt_set_key_usage, X.509 certificate API

gnutls_x509_crt_set_private_key_usage_period, X.509 certificate API

gnutls_x509_crt_set_proxy, X.509 certificate API

gnutls_x509_crt_set_proxy_dn, X.509 certificate API

gnutls_x509_crt_set_pubkey, Abstract key API

gnutls_x509_crt_set_serial, X.509 certificate API

gnutls_x509_crt_set_subject_alternative_name, X.509 certificate API

gnutls_x509_crt_set_subject_alt_name, X.509 certificate API

gnutls_x509_crt_set_subject_key_id, X.509 certificate API

gnutls_x509_crt_set_version, X.509 certificate API

gnutls_x509_crt_sign, X.509 certificate API

gnutls_x509_crt_sign2, X.509 certificate API

gnutls_x509_crt_verify, X.509 certificate API

gnutls_x509_crt_verify_data, Compatibility API

gnutls_x509_crt_verify_hash, Compatibility API

gnutls_x509_dn_deinit, X.509 certificate API

gnutls_x509_dn_export, X.509 certificate API

gnutls_x509_dn_get_rdn_ava, X.509 certificate API

gnutls_x509_dn_import, X.509 certificate API

gnutls_x509_dn_init, X.509 certificate API

gnutls_x509_dn_oid_known, X.509 certificate API

gnutls_x509_dn_oid_name, X.509 certificate API

gnutls_x509_privkey_cpy, X.509 certificate API

gnutls_x509_privkey_deinit, X.509 certificate API

gnutls_x509_privkey_export, X.509 certificate API

gnutls_x509_privkey_export_dsa_raw, X.509 certificate API

gnutls_x509_privkey_export_ecc_raw, X.509 certificate API

gnutls_x509_privkey_export_pkcs8, X.509 certificate API

gnutls_x509_privkey_export_rsa_raw, X.509 certificate API

gnutls_x509_privkey_export_rsa_raw2, X.509 certificate API

gnutls_x509_privkey_fix, X.509 certificate API

gnutls_x509_privkey_generate, X.509 certificate API

gnutls_x509_privkey_get_key_id, X.509 certificate API

gnutls_x509_privkey_get_pk_algorithm, X.509 certificate API

gnutls_x509_privkey_import, X.509 certificate API

gnutls_x509_privkey_import_dsa_raw, X.509 certificate API

gnutls_x509_privkey_import_ecc_raw, X.509 certificate API

gnutls_x509_privkey_import_pkcs8, X.509 certificate API

gnutls_x509_privkey_import_rsa_raw, X.509 certificate API

gnutls_x509_privkey_import_rsa_raw2, X.509 certificate API

gnutls_x509_privkey_init, X.509 certificate API

gnutls_x509_privkey_sec_param, X.509 certificate API

gnutls_x509_privkey_sign_data, Compatibility API

gnutls_x509_privkey_sign_hash, Compatibility API

gnutls_x509_privkey_verify_params, X.509 certificate API

gnutls_x509_rdn_get, X.509 certificate API

gnutls_x509_rdn_get_by_oid, X.509 certificate API

gnutls_x509_rdn_get_oid, X.509 certificate API

gnutls_x509_trust_list_add_cas, X.509 certificate API

gnutls_x509_trust_list_add_crls, X.509 certificate API

gnutls_x509_trust_list_add_named_crt, X.509 certificate API

gnutls_x509_trust_list_deinit, X.509 certificate API

gnutls_x509_trust_list_get_issuer, X.509 certificate API

gnutls_x509_trust_list_init, X.509 certificate API

gnutls_x509_trust_list_verify_crt, X.509 certificate API

gnutls_x509_trust_list_verify_named_crt, X.509 certificate API

H

hacking, Contributing

handshake protocol, The TLS handshake protocol

hardware security modules, Smart cards and HSMs

hardware tokens, Smart cards and HSMs

hash functions, Hash and HMAC functions

HMAC functions, Hash and HMAC functions

I

installation, Downloading and installing

internal architecture, Internal Architecture of GnuTLS

K

Key pinning, Verifying a certificate using trust on first use authentication

key sizes, Selecting cryptographic key sizes

keying material exporters, Keying material exporters

M

maximum fragment length, Maximum fragment length negotiation

O

OCSP, OCSP certificate status checking

OCSP Functions, OCSP API

ocsptool, Invoking ocsptool

ocsptool usage, Invoking ocsptool

ocsptool-ask, Invoking ocsptool

ocsptool-debug, Invoking ocsptool

ocsptool-generate-request, Invoking ocsptool

ocsptool-inder, Invoking ocsptool

ocsptool-infile, Invoking ocsptool

ocsptool-load-cert, Invoking ocsptool

ocsptool-load-issuer, Invoking ocsptool

ocsptool-load-request, Invoking ocsptool

ocsptool-load-response, Invoking ocsptool

ocsptool-load-signer, Invoking ocsptool

ocsptool-load-trust, Invoking ocsptool

ocsptool-nonce, Invoking ocsptool

ocsptool-outfile, Invoking ocsptool

ocsptool-request-info, Invoking ocsptool

ocsptool-response-info, Invoking ocsptool

ocsptool-verbose, Invoking ocsptool

ocsptool-verify-response, Invoking ocsptool

Online Certificate Status Protocol, OCSP certificate status checking

OpenPGP API, OpenPGP API

OpenPGP certificates, OpenPGP certificates

OpenPGP server, Echo server with OpenPGP authentication

OpenSSL, Compatibility with the OpenSSL library

P

p11tool, Invoking p11tool

p11tool usage, Invoking p11tool

p11tool-bits, Invoking p11tool

p11tool-debug, Invoking p11tool

p11tool-delete, Invoking p11tool

p11tool-detailed-url, Invoking p11tool

p11tool-export, Invoking p11tool

p11tool-generate-dsa, Invoking p11tool

p11tool-generate-ecc, Invoking p11tool

p11tool-generate-rsa, Invoking p11tool

p11tool-inder, Invoking p11tool

p11tool-initialize, Invoking p11tool

p11tool-inraw, Invoking p11tool

p11tool-label, Invoking p11tool

p11tool-list-all, Invoking p11tool

p11tool-list-all-certs, Invoking p11tool

p11tool-list-all-privkeys, Invoking p11tool

p11tool-list-all-trusted, Invoking p11tool

p11tool-list-certs, Invoking p11tool

p11tool-list-mechanisms, Invoking p11tool

p11tool-list-tokens, Invoking p11tool

p11tool-load-certificate, Invoking p11tool

p11tool-load-privkey, Invoking p11tool

p11tool-load-pubkey, Invoking p11tool

p11tool-login, Invoking p11tool

p11tool-outfile, Invoking p11tool

p11tool-pkcs8, Invoking p11tool

p11tool-private, Invoking p11tool

p11tool-provider, Invoking p11tool

p11tool-sec-param, Invoking p11tool

p11tool-secret-key, Invoking p11tool

p11tool-trusted, Invoking p11tool

p11tool-write, Invoking p11tool

parameter generation, Parameter generation

PCT, On SSL 2 and older protocols

PKCS #10, PKCS #10 certificate requests

PKCS #11 tokens, Smart cards and HSMs

PKCS #12, Managing encrypted keys

PKCS #8, Managing encrypted keys

Priority strings, Priority strings

PSK authentication, Authentication using PSK

psktool, Invoking psktool

psktool usage, Invoking psktool

psktool-debug, Invoking psktool

psktool-keysize, Invoking psktool

psktool-passwd, Invoking psktool

psktool-username, Invoking psktool

R

random numbers, Random number generation

record padding, On record padding

record protocol, The TLS record protocol

renegotiation, Safe renegotiation

reporting bugs, Bug Reports

resuming sessions, Resuming sessions, Session resumption

S

safe renegotiation, Safe renegotiation

server name indication, Server name indication

session resumption, Resuming sessions, Session resumption

session tickets, Session tickets

Smart card example, Using a smart card with TLS

smart cards, Smart cards and HSMs

SRP authentication, Authentication using SRP

srptool, Invoking srptool

srptool usage, Invoking srptool

srptool-create-conf, Invoking srptool

srptool-debug, Invoking srptool

srptool-index, Invoking srptool

srptool-passwd, Invoking srptool

srptool-passwd-conf, Invoking srptool

srptool-salt, Invoking srptool

srptool-username, Invoking srptool

srptool-verify, Invoking srptool

SSH-style authentication, Verifying a certificate using trust on first use authentication

SSL 2, On SSL 2 and older protocols

symmetric cryptography, Symmetric cryptography

symmetric encryption algorithms, Encryption algorithms used in the record layer

T

thread safety, Thread safety

tickets, Session tickets

TLS extensions, TLS extensions, Maximum fragment length negotiation, Server name indication, Session tickets

TLS layers, TLS layers

transport layer, The transport layer

transport protocol, The transport layer

Trust on first use, Verifying a certificate using trust on first use authentication

V

verifying certificate paths, Verifying X.509 certificate paths, Verifying a certificate in the context of TLS session, Verifying a certificate using trust on first use authentication

X

X.509 certificates, X.509 certificates

X.509 distinguished name, X.509 distinguished names

X.509 Functions, X.509 certificate API