org.spongycastle.crypto.digests

Class SkeinEngine

java.lang.Object

org.spongycastle.crypto.digests.SkeinEngine

All Implemented Interfaces:

Memoable

public class SkeinEngine
extends java.lang.Object
implements Memoable

Implementation of the Skein family of parameterised hash functions in 256, 512 and 1024 bit block sizes, based on the Threefish tweakable block cipher.

This is the 1.3 version of Skein defined in the Skein hash function submission to the NIST SHA-3 competition in October 2010.

Skein was designed by Niels Ferguson - Stefan Lucks - Bruce Schneier - Doug Whiting - Mihir Bellare - Tadayoshi Kohno - Jon Callas - Jesse Walker.

This implementation is the basis for SkeinDigest and SkeinMac, implementing the parameter based configuration system that allows Skein to be adapted to multiple applications.
Initialising the engine with SkeinParameters allows standard and arbitrary parameters to be applied during the Skein hash function.

Implemented:

• 256, 512 and 1024 bit internal states.
• Full 96 bit input length.
• Parameters defined in the Skein specification, and arbitrary other pre and post message parameters.
• Arbitrary output size in 1 byte intervals.

Not implemented:

• Sub-byte length input (bit padding).
• Tree hashing.

See Also:

SkeinParameters

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	SkeinEngine.Parameter

Field Summary

Fields

Modifier and Type	Field and Description
static int	SKEIN_1024 1024 bit block size - Skein 1024
static int	SKEIN_256 256 bit block size - Skein 256
static int	SKEIN_512 512 bit block size - Skein 512

Constructor Summary

Constructors

Constructor and Description
SkeinEngine(int blockSizeBits, int outputSizeBits) Constructs a Skein engine.
SkeinEngine(SkeinEngine engine) Creates a SkeinEngine as an exact copy of an existing instance.

Method Summary

Modifier and Type	Method and Description
Memoable	copy() Produce a copy of this object with its configuration and in its current state.
int	doFinal(byte[] out, int outOff)
int	getBlockSize()
int	getOutputSize()
void	init(SkeinParameters params) Initialises the Skein engine with the provided parameters.
void	reset() Reset the engine to the initial state (with the key and any pre-message parameters , ready to accept message input.
void	reset(Memoable other) Restore a copied object state into this object.
void	update(byte in)
void	update(byte[] in, int inOff, int len)

Methods inherited from class java.lang.Object

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

Field Detail

SKEIN_256

public static final int SKEIN_256

256 bit block size - Skein 256

See Also:

Constant Field Values

SKEIN_512

public static final int SKEIN_512

512 bit block size - Skein 512

See Also:

Constant Field Values

SKEIN_1024

public static final int SKEIN_1024

1024 bit block size - Skein 1024

See Also:

Constant Field Values

Constructor Detail

SkeinEngine

public SkeinEngine(int blockSizeBits,
                   int outputSizeBits)

Constructs a Skein engine.

Parameters:

blockSizeBits - the internal state size in bits - one of SKEIN_256, SKEIN_512 or SKEIN_1024.

outputSizeBits - the output/digest size to produce in bits, which must be an integral number of bytes.

SkeinEngine

public SkeinEngine(SkeinEngine engine)

Creates a SkeinEngine as an exact copy of an existing instance.

Method Detail

copy

public Memoable copy()

Description copied from interface: Memoable

Produce a copy of this object with its configuration and in its current state.

The returned object may be used simply to store the state, or may be used as a similar object starting from the copied state.

Specified by:

copy in interface Memoable

reset

public void reset(Memoable other)

Description copied from interface: Memoable

Restore a copied object state into this object.

Implementations of this method should try to avoid or minimise memory allocation to perform the reset.

Specified by:

reset in interface Memoable

Parameters:

other - an object originally copied from an object of the same type as this instance.

getOutputSize

public int getOutputSize()

getBlockSize

public int getBlockSize()

init

public void init(SkeinParameters params)

Initialises the Skein engine with the provided parameters. See SkeinParameters for details on the parameterisation of the Skein hash function.

Parameters:

params - the parameters to apply to this engine, or null to use no parameters.

reset

public void reset()

Reset the engine to the initial state (with the key and any pre-message parameters , ready to accept message input.

update

public void update(byte in)

update

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

doFinal

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