org.spongycastle.crypto.engines

Class ThreefishEngine

java.lang.Object

org.spongycastle.crypto.engines.ThreefishEngine

All Implemented Interfaces:

BlockCipher

public class ThreefishEngine
extends java.lang.Object
implements BlockCipher

Implementation of the Threefish tweakable large block cipher in 256, 512 and 1024 bit block sizes.

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

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

This implementation inlines all round functions, unrolls 8 rounds, and uses 1.2k of static tables to speed up key schedule injection.
2 x block size state is retained by each cipher instance.

Field Summary

Fields

Modifier and Type	Field and Description
static int	BLOCKSIZE_1024 1024 bit block size - Threefish-1024
static int	BLOCKSIZE_256 256 bit block size - Threefish-256
static int	BLOCKSIZE_512 512 bit block size - Threefish-512

Constructor Summary

Constructors

Constructor and Description
ThreefishEngine(int blocksizeBits) Constructs a new Threefish cipher, with a specified block size.

Method Summary

Modifier and Type	Method and Description
static long	bytesToWord(byte[] bytes, int off) Read a single 64 bit word from input in LSB first order.
java.lang.String	getAlgorithmName() Return the name of the algorithm the cipher implements.
int	getBlockSize() Return the block size for this cipher (in bytes).
void	init(boolean forEncryption, CipherParameters params) Initialise the engine.
void	init(boolean forEncryption, long[] key, long[] tweak) Initialise the engine, specifying the key and tweak directly.
int	processBlock(byte[] in, int inOff, byte[] out, int outOff) Process one block of input from the array in and write it to the out array.
int	processBlock(long[] in, long[] out) Process a block of data represented as 64 bit words.
void	reset() Reset the cipher.
static void	wordToBytes(long word, byte[] bytes, int off) Write a 64 bit word to output in LSB first order.

Methods inherited from class java.lang.Object

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

Field Detail

BLOCKSIZE_256

public static final int BLOCKSIZE_256

256 bit block size - Threefish-256

See Also:

Constant Field Values

BLOCKSIZE_512

public static final int BLOCKSIZE_512

512 bit block size - Threefish-512

See Also:

Constant Field Values

BLOCKSIZE_1024

public static final int BLOCKSIZE_1024

1024 bit block size - Threefish-1024

See Also:

Constant Field Values

Constructor Detail

ThreefishEngine

public ThreefishEngine(int blocksizeBits)

Constructs a new Threefish cipher, with a specified block size.

Parameters:

blocksizeBits - the block size in bits, one of BLOCKSIZE_256, BLOCKSIZE_512, BLOCKSIZE_1024.

Method Detail

init

public void init(boolean forEncryption,
                 CipherParameters params)
          throws java.lang.IllegalArgumentException

Initialise the engine.

Specified by:

init in interface BlockCipher

Parameters:

params - an instance of TweakableBlockCipherParameters, or KeyParameter (to use a 0 tweak)

forEncryption - if true the cipher is initialised for encryption, if false for decryption.

Throws:

java.lang.IllegalArgumentException - if the params argument is inappropriate.

init

public void init(boolean forEncryption,
                 long[] key,
                 long[] tweak)

Initialise the engine, specifying the key and tweak directly.

Parameters:

forEncryption - the cipher mode.

key - the words of the key, or null to use the current key.

tweak - the 2 word (128 bit) tweak, or null to use the current tweak.

getAlgorithmName

public java.lang.String getAlgorithmName()

Description copied from interface: BlockCipher

Return the name of the algorithm the cipher implements.

Specified by:

getAlgorithmName in interface BlockCipher

Returns:

the name of the algorithm the cipher implements.

getBlockSize

public int getBlockSize()

Description copied from interface: BlockCipher

Return the block size for this cipher (in bytes).

Specified by:

getBlockSize in interface BlockCipher

Returns:

the block size for this cipher in bytes.

reset

public void reset()

Description copied from interface: BlockCipher

Reset the cipher. After resetting the cipher is in the same state as it was after the last init (if there was one).

Specified by:

reset in interface BlockCipher

processBlock

public int processBlock(byte[] in,
                        int inOff,
                        byte[] out,
                        int outOff)
                 throws DataLengthException,
                        java.lang.IllegalStateException

Description copied from interface: BlockCipher

Process one block of input from the array in and write it to the out array.

Specified by:

processBlock in interface BlockCipher

Parameters:

in - the array containing the input data.

inOff - offset into the in array the data starts at.

out - the array the output data will be copied into.

outOff - the offset into the out array the output will start at.

Returns:

the number of bytes processed and produced.

Throws:

DataLengthException - if there isn't enough data in in, or space in out.

java.lang.IllegalStateException - if the cipher isn't initialised.

processBlock

public int processBlock(long[] in,
                        long[] out)
                 throws DataLengthException,
                        java.lang.IllegalStateException

Process a block of data represented as 64 bit words.

Parameters:

in - a block sized buffer of words to process.

out - a block sized buffer of words to receive the output of the operation.

Returns:

the number of 8 byte words processed (which will be the same as the block size).

Throws:

DataLengthException - if either the input or output is not block sized.

java.lang.IllegalStateException - if this engine is not initialised.

bytesToWord

public static long bytesToWord(byte[] bytes,
                               int off)

Read a single 64 bit word from input in LSB first order.

wordToBytes

public static void wordToBytes(long word,
                               byte[] bytes,
                               int off)

Write a 64 bit word to output in LSB first order.