gnu.crypto.hash
Class Sha160

java.lang.Object
  gnu.crypto.hash.BaseHash
      gnu.crypto.hash.Sha160

All Implemented Interfaces:

java.lang.Cloneable, IMessageDigest

public class Sha160

extends BaseHash

The Secure Hash Algorithm (SHA-1) is required for use with the Digital Signature Algorithm (DSA) as specified in the Digital Signature Standard (DSS) and whenever a secure hash algorithm is required for federal applications. For a message of length less than 2^64 bits, the SHA-1 produces a 160-bit condensed representation of the message called a message digest. The message digest is used during generation of a signature for the message. The SHA-1 is also used to compute a message digest for the received version of the message during the process of verifying the signature. Any change to the message in transit will, with very high probability, result in a different message digest, and the signature will fail to verify.

The SHA-1 is designed to have the following properties: it is computationally infeasible to find a message which corresponds to a given message digest, or to find two different messages which produce the same message digest.

References:

1. SECURE HASH STANDARD
   Federal Information, Processing Standards Publication 180-1, 1995 April 17.

Version:

$Revision: 1.2 $

Field Summary

Fields inherited from class gnu.crypto.hash.BaseHash

blockSize, buffer, count, hashSize, name

Constructor Summary

Sha160()
Trivial 0-arguments constructor.

Method Summary

java.lang.Object	clone() Returns a clone copy of this instance.
static int[]	G(int hh0, int hh1, int hh2, int hh3, int hh4, byte[] in, int offset)
protected byte[]	getResult() Constructs the result from the contents of the current context.
protected byte[]	padBuffer() Returns the byte array to use as padding before completing a hash operation.
protected void	resetContext() Resets the instance for future re-use.
boolean	selfTest() A basic test.
protected void	transform(byte[] in, int offset) The block digest transformation per se.

Methods inherited from class gnu.crypto.hash.BaseHash

blockSize, digest, hashSize, name, reset, update, update

Methods inherited from class java.lang.Object

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

Constructor Detail

Sha160

public Sha160()

Trivial 0-arguments constructor.

Method Detail

G

public static final int[] G(int hh0,
                            int hh1,
                            int hh2,
                            int hh3,
                            int hh4,
                            byte[] in,
                            int offset)

clone

public java.lang.Object clone()

Description copied from interface: IMessageDigest

Returns a clone copy of this instance.

Specified by:

clone in interface IMessageDigest

Specified by:

clone in class BaseHash

transform

protected void transform(byte[] in,
                         int offset)

Description copied from class: BaseHash

The block digest transformation per se.

Specified by:

transform in class BaseHash

Parameters:

in - the blockSize long block, as an array of bytes to digest.

offset - the index where the data to digest is located within the input buffer.

padBuffer

protected byte[] padBuffer()

Description copied from class: BaseHash

Returns the byte array to use as padding before completing a hash operation.

Specified by:

padBuffer in class BaseHash

Returns:

the bytes to pad the remaining bytes in the buffer before completing a hash operation.

getResult

protected byte[] getResult()

Description copied from class: BaseHash

Constructs the result from the contents of the current context.

Specified by:

getResult in class BaseHash

Returns:

the output of the completed hash operation.

resetContext

protected void resetContext()

Description copied from class: BaseHash

Resets the instance for future re-use.

Specified by:

resetContext in class BaseHash

selfTest

public boolean selfTest()

Description copied from interface: IMessageDigest

A basic test. Ensures that the digest of a pre-determined message is equal to a known pre-computed value.

Specified by:

selfTest in interface IMessageDigest

Specified by:

selfTest in class BaseHash