gnu.crypto.hash

Class BaseHash

Implemented Interfaces:
Cloneable, IMessageDigest
Known Direct Subclasses:
Haval, MD2, MD4, MD5, RipeMD128, RipeMD160, Sha160, Sha256, Sha384, Sha512, Tiger, Whirlpool

public abstract class BaseHash
extends Object
implements IMessageDigest

A base abstract class to facilitate hash implementations.
Version:
$Revision: 1.10 $

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 String
name
The canonical name prefix of the hash.

Constructor Summary

BaseHash(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 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.
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)
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.
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.

Field Details

blockSize

protected int blockSize
The hash (inner) block size in bytes.

buffer

protected byte[] buffer
Temporary input buffer.

count

protected long count
Number of bytes processed so far.

hashSize

protected int hashSize
The hash (output) size in bytes.

name

protected String name
The canonical name prefix of the hash.

Constructor Details

BaseHash

protected BaseHash(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 Details

blockSize

public int blockSize()
Returns the algorithm's (inner) block size in bytes.
Specified by:
blockSize in interface IMessageDigest
Returns:
the algorithm's inner block size in bytes.

clone

public abstract Object clone()
Returns a clone copy of this instance.
Specified by:
clone in interface IMessageDigest
Returns:
a clone copy of this instance.

digest

public byte[] digest()
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.

getResult

protected abstract byte[] getResult()
Constructs the result from the contents of the current context.
Returns:
the output of the completed hash operation.

hashSize

public int hashSize()
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.

name

public String name()
Returns the canonical name of this algorithm.
Specified by:
name in interface IMessageDigest
Returns:
the canonical name of this instance.

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.

reset

public void reset()
Resets the current context of this instance clearing any eventually cached intermediary values.
Specified by:
reset in interface IMessageDigest

resetContext

protected abstract void resetContext()
Resets the instance for future re-use.

selfTest

public abstract boolean selfTest()
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.

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.

update

public void update(byte b)
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)
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:

update

public 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.
Specified by:
update in interface IMessageDigest
Parameters:
offset - start of meaningful bytes in input block.

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