com.arxanfintech.common.crypto.core.cryptohash

Class DigestEngine

java.lang.Object

com.arxanfintech.common.crypto.core.cryptohash.DigestEngine

All Implemented Interfaces:

Digest

Direct Known Subclasses:

Keccak256, Keccak512

public abstract class DigestEngine
extends Object
implements Digest

Constructor Summary

Constructors

Constructor and Description
DigestEngine() Instantiate the engine.

Method Summary

Modifier and Type	Method and Description
protected Digest	copyState(DigestEngine dest) This function copies the internal buffering state to some other instance of a class extending DigestEngine.
byte[]	digest() Finalize the current hash computation and return the hash value in a newly-allocated array.
byte[]	digest(byte[] input) Input some bytes, then finalize the current hash computation and return the hash value in a newly-allocated array.
int	digest(byte[] buf, int offset, int len) Finalize the current hash computation and store the hash value in the provided output buffer.
protected abstract void	doInit() This function is called at object creation time; the implementation should use it to perform initialization tasks.
protected abstract void	doPadding(byte[] buf, int off) Perform the final padding and store the result in the provided buffer.
protected abstract void	engineReset() Reset the hash algorithm state.
protected int	flush() Flush internal buffers, so that less than a block of data may at most be upheld.
protected byte[]	getBlockBuffer() Get a reference to an internal buffer with the same size than a block.
protected long	getBlockCount() Get the "block count": this is the number of times the processBlock(byte[]) method has been invoked for the current hash operation.
protected int	getInternalBlockLength() Get the internal block length.
protected abstract void	processBlock(byte[] data) Process one block of data.
void	reset() Reset the object: this makes it suitable for a new hash computation.
void	update(byte input) Insert one more input data byte.
void	update(byte[] input) Insert some more bytes.
void	update(byte[] input, int offset, int len) Insert some more bytes.

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.arxanfintech.common.crypto.core.cryptohash.Digest

copy, getBlockLength, getDigestLength, toString

Constructor Detail

DigestEngine

public DigestEngine()

Instantiate the engine.

Method Detail

engineReset

protected abstract void engineReset()

Reset the hash algorithm state.

processBlock

protected abstract void processBlock(byte[] data)

Process one block of data.

Parameters:

data - the data block

doPadding

protected abstract void doPadding(byte[] buf,
                                  int off)

Perform the final padding and store the result in the provided buffer. This method shall call flush() and then update(byte) with the appropriate padding data in order to get the full input data.

Parameters:

buf - the output buffer

off - the output offset

doInit

protected abstract void doInit()

This function is called at object creation time; the implementation should use it to perform initialization tasks. After this method is called, the implementation should be ready to process data or meaningfully honour calls such as Digest.getDigestLength()

digest

public byte[] digest()

Description copied from interface: Digest

Finalize the current hash computation and return the hash value in a newly-allocated array. The object is resetted.

Specified by:

digest in interface Digest

Returns:

the hash output

digest

public byte[] digest(byte[] input)

Description copied from interface: Digest

Input some bytes, then finalize the current hash computation and return the hash value in a newly-allocated array. The object is resetted.

Specified by:

digest in interface Digest

Parameters:

input - the input data

Returns:

the hash output

digest

public int digest(byte[] buf,
                  int offset,
                  int len)

Description copied from interface: Digest

Finalize the current hash computation and store the hash value in the provided output buffer. The len parameter contains the maximum number of bytes that should be written; no more bytes than the natural hash function output length will be produced. If len is smaller than the natural hash output length, the hash output is truncated to its first len bytes. The object is resetted.

Specified by:

digest in interface Digest

Parameters:

buf - the output buffer

offset - the output offset within outbuf

len - the requested hash output length (in bytes)

Returns:

the number of bytes actually written in outbuf

reset

public void reset()

Description copied from interface: Digest

Reset the object: this makes it suitable for a new hash computation. The current computation, if any, is discarded.

Specified by:

reset in interface Digest

update

public void update(byte input)

Description copied from interface: Digest

Insert one more input data byte.

Specified by:

update in interface Digest

Parameters:

input - the input byte

update

public void update(byte[] input)

Description copied from interface: Digest

Insert some more bytes.

Specified by:

update in interface Digest

Parameters:

input - the data bytes

update

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

Description copied from interface: Digest

Insert some more bytes.

Specified by:

update in interface Digest

Parameters:

input - the data buffer

offset - the data offset in inbuf

len - the data length (in bytes)

getInternalBlockLength

protected int getInternalBlockLength()

Get the internal block length. This is the length (in bytes) of the array which will be passed as parameter to processBlock(byte[]). The default implementation of this method calls Digest.getBlockLength() and returns the same value. Overriding this method is useful when the advertised block length (which is used, for instance, by HMAC) is suboptimal with regards to internal buffering needs.

Returns:

the internal block length (in bytes)

flush

protected final int flush()

Flush internal buffers, so that less than a block of data may at most be upheld.

Returns:

the number of bytes still unprocessed after the flush

getBlockBuffer

protected final byte[] getBlockBuffer()

Get a reference to an internal buffer with the same size than a block. The contents of that buffer are defined only immediately after a call to flush(): if flush() return the value n, then the first n bytes of the array returned by this method are the n bytes of input data which are still unprocessed. The values of the remaining bytes are undefined and may be altered at will.

Returns:

a block-sized internal buffer

getBlockCount

protected long getBlockCount()

Get the "block count": this is the number of times the processBlock(byte[]) method has been invoked for the current hash operation. That counter is incremented after the call to processBlock(byte[]).

Returns:

the block count

copyState

protected Digest copyState(DigestEngine dest)

This function copies the internal buffering state to some other instance of a class extending DigestEngine. It returns a reference to the copy. This method is intended to be called by the implementation of the Digest.copy() method.

Parameters:

dest - the copy

Returns:

the value dest