gnu.crypto.hash
Class BaseHash

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

All Implemented Interfaces:

java.lang.Cloneable, IMessageDigest

Direct Known Subclasses:

Haval, MD2, MD4, MD5, RipeMD128, RipeMD160, Sha160, Sha256, Sha384, Sha512, Tiger, Whirlpool

public abstract class BaseHash

extends java.lang.Object

implements IMessageDigest

A base abstract class to facilitate hash implementations.

Version:

$Revision: 1.2 $

Field Summary

protected int	blockSize The hash (inner) block size in bytes.
protected byte[]	buffer Temporary input buffer.
protected long	count Number of bytes processed so far.
protected int	hashSize The hash (output) size in bytes.
protected java.lang.String	name The canonical name prefix of the hash.

Constructor Summary

protected

BaseHash(java.lang.String name, int hashSize, int blockSize) Trivial constructor for use by concrete subclasses.

Method Summary

int	blockSize() Returns the algorithm's (inner) block size in bytes.
abstract java.lang.Object	clone() Returns a clone copy of this instance.
byte[]	digest() Completes the message digest by performing final operations such as padding and resetting the instance.
protected abstract byte[]	getResult() Constructs the result from the contents of the current context.
int	hashSize() Returns the output length in bytes of this message digest algorithm.
java.lang.String	name() Returns the canonical name of this algorithm.
protected abstract byte[]	padBuffer() Returns the byte array to use as padding before completing a hash operation.
void	reset() Resets the current context of this instance clearing any eventually cached intermediary values.
protected abstract void	resetContext() Resets the instance for future re-use.
abstract boolean	selfTest() A basic test.
protected abstract void	transform(byte[] in, int offset) The block digest transformation per se.
void	update(byte b) Continues a message digest operation using the input byte.
void	update(byte[] b, int offset, int len) Continues a message digest operation, by filling the buffer, processing data in the algorithm's HASH_SIZE-bit block(s), updating the context and count, and buffering the remaining bytes in buffer for the next operation.

Methods inherited from class java.lang.Object

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

Field Detail

name

protected java.lang.String name

The canonical name prefix of the hash.

hashSize

protected int hashSize

The hash (output) size in bytes.

blockSize

protected int blockSize

The hash (inner) block size in bytes.

count

protected long count

Number of bytes processed so far.

buffer

protected byte[] buffer

Temporary input buffer.

Constructor Detail

BaseHash

protected BaseHash(java.lang.String name,
                   int hashSize,
                   int blockSize)

Trivial constructor for use by concrete subclasses.

Parameters:

name - the canonical name prefix of this instance.

hashSize - the block size of the output in bytes.

blockSize - the block size of the internal transform.

Method Detail

name

public java.lang.String name()

Description copied from interface: IMessageDigest

Returns the canonical name of this algorithm.

Specified by:

name in interface IMessageDigest

Returns:

the canonical name of this instance.

hashSize

public int hashSize()

Description copied from interface: IMessageDigest

Returns the output length in bytes of this message digest algorithm.

Specified by:

hashSize in interface IMessageDigest

Returns:

the output length in bytes of this message digest algorithm.

blockSize

public int blockSize()

Description copied from interface: IMessageDigest

Returns the algorithm's (inner) block size in bytes.

Specified by:

blockSize in interface IMessageDigest

Returns:

the algorithm's inner block size in bytes.

update

public void update(byte b)

Description copied from interface: IMessageDigest

Continues a message digest operation using the input byte.

Specified by:

update in interface IMessageDigest

Parameters:

b - the input byte to digest.

update

public void update(byte[] b,
                   int offset,
                   int len)

Description copied from interface: IMessageDigest

Continues a message digest operation, by filling the buffer, processing data in the algorithm's HASH_SIZE-bit block(s), updating the context and count, and buffering the remaining bytes in buffer for the next operation.

Specified by:

update in interface IMessageDigest

Parameters:

b - the input block.

offset - start of meaningful bytes in input block.

len - number of bytes, in input block, to consider.

digest

public byte[] digest()

Description copied from interface: IMessageDigest

Completes the message digest by performing final operations such as padding and resetting the instance.

Specified by:

digest in interface IMessageDigest

Returns:

the array of bytes representing the hash value.

reset

public void reset()

Description copied from interface: IMessageDigest

Resets the current context of this instance clearing any eventually cached intermediary values.

Specified by:

reset in interface IMessageDigest

clone

public abstract java.lang.Object clone()

Description copied from interface: IMessageDigest

Returns a clone copy of this instance.

Specified by:

clone in interface IMessageDigest

selfTest

public abstract 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

Returns:

true if the implementation passes a basic self-test. Returns false otherwise.

padBuffer

protected abstract byte[] padBuffer()

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

Returns:

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

getResult

protected abstract byte[] getResult()

Constructs the result from the contents of the current context.

Returns:

the output of the completed hash operation.

resetContext

protected abstract void resetContext()

Resets the instance for future re-use.

transform

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

The block digest transformation per se.

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.