org.bouncycastle.crypto.digests
Class ShortenedDigest

java.lang.Object
  org.bouncycastle.crypto.digests.ShortenedDigest

All Implemented Interfaces:

Digest, ExtendedDigest

public class ShortenedDigest
extends java.lang.Object
implements ExtendedDigest

Wrapper class that reduces the output length of a particular digest to only the first n bytes of the digest function.

Constructor Summary

ShortenedDigest(ExtendedDigest baseDigest, int length)
Base constructor.

Method Summary

int	doFinal(byte[] out, int outOff) close the digest, producing the final digest value.
java.lang.String	getAlgorithmName() return the algorithm name
int	getByteLength() Return the size in bytes of the internal buffer the digest applies it's compression function to.
int	getDigestSize() return the size, in bytes, of the digest produced by this message digest.
void	reset() reset the digest back to it's initial state.
void	update(byte in) update the message digest with a single byte.
void	update(byte[] in, int inOff, int len) update the message digest with a block of bytes.

Methods inherited from class java.lang.Object

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

Constructor Detail

ShortenedDigest

public ShortenedDigest(ExtendedDigest baseDigest,
                       int length)

Base constructor.

Parameters:

baseDigest - underlying digest to use.

length - length in bytes of the output of doFinal.

Throws:

java.lang.IllegalArgumentException - if baseDigest is null, or length is greater than baseDigest.getDigestSize().

Method Detail

getAlgorithmName

public java.lang.String getAlgorithmName()

Description copied from interface: Digest

return the algorithm name

Specified by:

getAlgorithmName in interface Digest

Returns:

the algorithm name

getDigestSize

public int getDigestSize()

Description copied from interface: Digest

return the size, in bytes, of the digest produced by this message digest.

Specified by:

getDigestSize in interface Digest

Returns:

the size, in bytes, of the digest produced by this message digest.

update

public void update(byte in)

Description copied from interface: Digest

update the message digest with a single byte.

Specified by:

update in interface Digest

Parameters:

in - the input byte to be entered.

update

public void update(byte[] in,
                   int inOff,
                   int len)

Description copied from interface: Digest

update the message digest with a block of bytes.

Specified by:

update in interface Digest

Parameters:

in - the byte array containing the data.

inOff - the offset into the byte array where the data starts.

len - the length of the data.

doFinal

public int doFinal(byte[] out,
                   int outOff)

Description copied from interface: Digest

close the digest, producing the final digest value. The doFinal call leaves the digest reset.

Specified by:

doFinal in interface Digest

Parameters:

out - the array the digest is to be copied into.

outOff - the offset into the out array the digest is to start at.

reset

public void reset()

Description copied from interface: Digest

reset the digest back to it's initial state.

Specified by:

reset in interface Digest

getByteLength

public int getByteLength()

Description copied from interface: ExtendedDigest

Return the size in bytes of the internal buffer the digest applies it's compression function to.

Specified by:

getByteLength in interface ExtendedDigest

Returns:

byte length of the digests internal buffer.