org.bouncycastle.crypto.engines
Class TwofishEngine

java.lang.Object
  org.bouncycastle.crypto.engines.TwofishEngine

All Implemented Interfaces:

BlockCipher

public final class TwofishEngine
extends java.lang.Object
implements BlockCipher

A class that provides Twofish encryption operations. This Java implementation is based on the Java reference implementation provided by Bruce Schneier and developed by Raif S. Naffah.

Field Summary

private static int	BLOCK_SIZE
private boolean	encrypting
private static int	GF256_FDBK
private static int	GF256_FDBK_2
private static int	GF256_FDBK_4
private int[]	gMDS0
private int[]	gMDS1
private int[]	gMDS2
private int[]	gMDS3
private int[]	gSBox
private int[]	gSubKeys gSubKeys[] and gSBox[] are eventually used in the encryption and decryption methods.
private static int	INPUT_WHITEN
private int	k64Cnt
private static int	MAX_KEY_BITS
private static int	MAX_ROUNDS
private static int	OUTPUT_WHITEN
private static byte[][]	P
private static int	P_00 Define the fixed p0/p1 permutations used in keyed S-box lookup.
private static int	P_01
private static int	P_02
private static int	P_03
private static int	P_04
private static int	P_10
private static int	P_11
private static int	P_12
private static int	P_13
private static int	P_14
private static int	P_20
private static int	P_21
private static int	P_22
private static int	P_23
private static int	P_24
private static int	P_30
private static int	P_31
private static int	P_32
private static int	P_33
private static int	P_34
private static int	ROUND_SUBKEYS
private static int	ROUNDS
private static int	RS_GF_FDBK
private static int	SK_BUMP
private static int	SK_ROTL
private static int	SK_STEP
private static int	TOTAL_SUBKEYS
private byte[]	workingKey

Constructor Summary

TwofishEngine()

Method Summary

private int	b0(int x)
private int	b1(int x)
private int	b2(int x)
private int	b3(int x)
private void	Bits32ToBytes(int in, byte[] b, int offset)
private int	BytesTo32Bits(byte[] b, int p)
private void	decryptBlock(byte[] src, int srcIndex, byte[] dst, int dstIndex) Decrypt the given input starting at the given offset and place the result in the provided buffer starting at the given offset.
private void	encryptBlock(byte[] src, int srcIndex, byte[] dst, int dstIndex) Encrypt the given input starting at the given offset and place the result in the provided buffer starting at the given offset.
private int	F32(int x, int[] k32)
private int	Fe32_0(int x)
private int	Fe32_3(int x)
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 encrypting, CipherParameters params) initialise a Twofish cipher.
private int	LFSR1(int x)
private int	LFSR2(int x)
private int	Mx_X(int x)
private int	Mx_Y(int x)
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.
void	reset() Reset the cipher.
private int	RS_MDS_Encode(int k0, int k1) Use (12, 8) Reed-Solomon code over GF(256) to produce a key S-box 32-bit entity from 2 key material 32-bit entities.
private int	RS_rem(int x) Reed-Solomon code parameters: (12,8) reversible code:
private void	setKey(byte[] key)

Methods inherited from class java.lang.Object

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

Field Detail

P

private static final byte[][] P

P_00

private static final int P_00

Define the fixed p0/p1 permutations used in keyed S-box lookup. By changing the following constant definitions, the S-boxes will automatically get changed in the Twofish engine.

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Constant Field Values

P_01

private static final int P_01

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P_02

private static final int P_02

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P_03

private static final int P_03

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P_04

private static final int P_04

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P_10

private static final int P_10

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P_11

private static final int P_11

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P_12

private static final int P_12

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P_13

private static final int P_13

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P_14

private static final int P_14

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P_20

private static final int P_20

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P_21

private static final int P_21

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P_22

private static final int P_22

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P_23

private static final int P_23

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P_24

private static final int P_24

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P_30

private static final int P_30

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P_31

private static final int P_31

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P_32

private static final int P_32

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P_33

private static final int P_33

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P_34

private static final int P_34

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GF256_FDBK

private static final int GF256_FDBK

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GF256_FDBK_2

private static final int GF256_FDBK_2

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GF256_FDBK_4

private static final int GF256_FDBK_4

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RS_GF_FDBK

private static final int RS_GF_FDBK

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ROUNDS

private static final int ROUNDS

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MAX_ROUNDS

private static final int MAX_ROUNDS

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BLOCK_SIZE

private static final int BLOCK_SIZE

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MAX_KEY_BITS

private static final int MAX_KEY_BITS

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INPUT_WHITEN

private static final int INPUT_WHITEN

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OUTPUT_WHITEN

private static final int OUTPUT_WHITEN

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ROUND_SUBKEYS

private static final int ROUND_SUBKEYS

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TOTAL_SUBKEYS

private static final int TOTAL_SUBKEYS

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SK_STEP

private static final int SK_STEP

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SK_BUMP

private static final int SK_BUMP

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SK_ROTL

private static final int SK_ROTL

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Constant Field Values

encrypting

private boolean encrypting

gMDS0

private int[] gMDS0

gMDS1

private int[] gMDS1

gMDS2

private int[] gMDS2

gMDS3

private int[] gMDS3

gSubKeys

private int[] gSubKeys

gSubKeys[] and gSBox[] are eventually used in the encryption and decryption methods.

gSBox

private int[] gSBox

k64Cnt

private int k64Cnt

workingKey

private byte[] workingKey

Constructor Detail

TwofishEngine

public TwofishEngine()

Method Detail

init

public void init(boolean encrypting,
                 CipherParameters params)

initialise a Twofish cipher.

Specified by:

init in interface BlockCipher

Parameters:

encrypting - whether or not we are for encryption.

params - the parameters required to set up the cipher.

Throws:

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

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.

processBlock

public final int processBlock(byte[] in,
                              int inOff,
                              byte[] out,
                              int outOff)

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.

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

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.

setKey

private void setKey(byte[] key)

encryptBlock

private void encryptBlock(byte[] src,
                          int srcIndex,
                          byte[] dst,
                          int dstIndex)

Encrypt the given input starting at the given offset and place the result in the provided buffer starting at the given offset. The input will be an exact multiple of our blocksize. encryptBlock uses the pre-calculated gSBox[] and subKey[] arrays.

decryptBlock

private void decryptBlock(byte[] src,
                          int srcIndex,
                          byte[] dst,
                          int dstIndex)

Decrypt the given input starting at the given offset and place the result in the provided buffer starting at the given offset. The input will be an exact multiple of our blocksize.

F32

private final int F32(int x,
                      int[] k32)

RS_MDS_Encode

private final int RS_MDS_Encode(int k0,
                                int k1)

Use (12, 8) Reed-Solomon code over GF(256) to produce a key S-box 32-bit entity from 2 key material 32-bit entities.

Parameters:

k0 - first 32-bit entity

k1 - second 32-bit entity

Returns:

Remainder polynomial generated using RS code

RS_rem

private final int RS_rem(int x)

Reed-Solomon code parameters: (12,8) reversible code:

 g(x) = x^4 + (a+1/a)x^3 + ax^2 + (a+1/a)x + 1
 

where a = primitive root of field generator 0x14D

LFSR1

private final int LFSR1(int x)

LFSR2

private final int LFSR2(int x)

Mx_X

private final int Mx_X(int x)

Mx_Y

private final int Mx_Y(int x)

b0

private final int b0(int x)

b1

private final int b1(int x)

b2

private final int b2(int x)

b3

private final int b3(int x)

Fe32_0

private final int Fe32_0(int x)

Fe32_3

private final int Fe32_3(int x)

BytesTo32Bits

private final int BytesTo32Bits(byte[] b,
                                int p)

Bits32ToBytes

private final void Bits32ToBytes(int in,
                                 byte[] b,
                                 int offset)