gnu.crypto.sig.rsa
Class EMSA_PKCS1_V1_5

java.lang.Object
  gnu.crypto.sig.rsa.EMSA_PKCS1_V1_5

All Implemented Interfaces:

java.lang.Cloneable

public class EMSA_PKCS1_V1_5

extends java.lang.Object

implements java.lang.Cloneable

An implementation of the EMSA-PKCS1-V1.5 encoding scheme.

EMSA-PKCS1-V1.5 is parameterised by the choice of hash function Hash and hLen which denotes the length in octets of the hash function output.

References:

1. Public-Key Cryptography Standards (PKCS) #1:
   RSA Cryptography Specifications Version 2.1.
   Jakob Jonsson and Burt Kaliski.

Version:

$Revision: 1.2 $

Method Summary

java.lang.Object	clone()
byte[]	encode(byte[] mHash, int emLen) Frames the hash of a message, along with an ID of the hash function in a DER sequence according to the specifications of EMSA-PKCS1-V1.5 as described in RFC-3447 (see class documentation).
static EMSA_PKCS1_V1_5	getInstance(java.lang.String mdName) Returns an instance of this object given a designated name of a hash function.

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

getInstance

public static final EMSA_PKCS1_V1_5 getInstance(java.lang.String mdName)

Returns an instance of this object given a designated name of a hash function.

Parameters:

mdName - the canonical name of a hash function.

Returns:

an instance of this object configured for use with the designated options.

Throws:

java.lang.UnsupportedOperationException - if the hash function is not implemented or does not have an ID listed in RFC-3447.

clone

public java.lang.Object clone()

encode

public byte[] encode(byte[] mHash,
                     int emLen)

Frames the hash of a message, along with an ID of the hash function in a DER sequence according to the specifications of EMSA-PKCS1-V1.5 as described in RFC-3447 (see class documentation).

Parameters:

mHash - the byte sequence resulting from applying the message digest algorithm Hash to the message M.

emLen - intended length in octets of the encoded message, at least tLen + 11, where tLen is the octet length of the DER encoding T of a certain value computed during the encoding operation.

Returns:

encoded message, an octet string of length emLen.

Throws:

java.lang.IllegalArgumentException - if the message is too long, or if the intended encoded message length is too short.