gnu.javax.crypto.cipher

Class Twofish

Implemented Interfaces:
Cloneable, IBlockCipher, gnu.javax.crypto.cipher.IBlockCipherSpi

public final class Twofish
extends BaseCipher

Twofish is a balanced 128-bit Feistel cipher, consisting of 16 rounds. In each round, a 64-bit S-box value is computed from 64 bits of the block, and this value is xored into the other half of the block. The two half-blocks are then exchanged, and the next round begins. Before the first round, all input bits are xored with key-dependent "whitening" subkeys, and after the final round the output bits are xored with other key-dependent whitening subkeys; these subkeys are not used anywhere else in the algorithm.

Twofish is designed by Bruce Schneier, Doug Whiting, John Kelsey, Chris Hall, David Wagner and Niels Ferguson.

References:

  1. Twofish: A 128-bit Block Cipher.

Field Summary

Fields inherited from class gnu.javax.crypto.cipher.BaseCipher

currentBlockSize, currentKey, defaultBlockSize, defaultKeySize, lock, name

Fields inherited from interface gnu.javax.crypto.cipher.IBlockCipher

CIPHER_BLOCK_SIZE, KEY_MATERIAL

Constructor Summary

Twofish()
Trivial 0-arguments constructor.

Method Summary

Iterator<E>
blockSizes()
Returns an Iterator over the supported block sizes.
Object
clone()
Returns a clone of this instance.
void
decrypt(byte[] in, int inOffset, byte[] out, int outOffset, Object sessionKey, int bs)
Decrypts exactly one block of ciphertext.
void
encrypt(byte[] in, int inOffset, byte[] out, int outOffset, Object sessionKey, int bs)
Encrypts exactly one block of plaintext.
Iterator<E>
keySizes()
Returns an Iterator over the supported key sizes.
Object
makeKey(byte[] k, int bs)
Expands a user-supplied key material into a session key for a designated block size.
boolean
selfTest()
A correctness test that consists of basic symmetric encryption / decryption test(s) for all supported block and key sizes, as well as one (1) variable key Known Answer Test (KAT).

Methods inherited from class gnu.javax.crypto.cipher.BaseCipher

clone, currentBlockSize, decryptBlock, defaultBlockSize, defaultKeySize, encryptBlock, init, name, reset, selfTest, testKat, testKat

Methods inherited from class java.lang.Object

clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

Twofish

public Twofish()
Trivial 0-arguments constructor.

Method Details

blockSizes

public Iterator<E> blockSizes()
Returns an Iterator over the supported block sizes. Each element returned by this object is an Integer.
Specified by:
blockSizes in interface IBlockCipher
blockSizes in interface gnu.javax.crypto.cipher.IBlockCipherSpi
Returns:
an Iterator over the supported block sizes.

clone

public Object clone()
Returns a clone of this instance.
Specified by:
clone in interface IBlockCipher
Overrides:
clone in interface BaseCipher
Returns:
a clone copy of this instance.

decrypt

public void decrypt(byte[] in,
                    int inOffset,
                    byte[] out,
                    int outOffset,
                    Object sessionKey,
                    int bs)
Decrypts exactly one block of ciphertext.
Specified by:
decrypt in interface gnu.javax.crypto.cipher.IBlockCipherSpi
Parameters:
in - the ciphertext.
inOffset - index of in from which to start considering data.
out - the plaintext.
outOffset - index of out from which to store the result.
bs - the block size to use.
Throws:
IllegalArgumentException - if the block size is invalid.
ArrayIndexOutOfBoundsException - if there is not enough room in either the plaintext or ciphertext buffers.

encrypt

public void encrypt(byte[] in,
                    int inOffset,
                    byte[] out,
                    int outOffset,
                    Object sessionKey,
                    int bs)
Encrypts exactly one block of plaintext.
Specified by:
encrypt in interface gnu.javax.crypto.cipher.IBlockCipherSpi
Parameters:
in - the plaintext.
inOffset - index of in from which to start considering data.
out - the ciphertext.
outOffset - index of out from which to store the result.
bs - the block size to use.
Throws:
IllegalArgumentException - if the block size is invalid.
ArrayIndexOutOfBoundsException - if there is not enough room in either the plaintext or ciphertext buffers.

keySizes

public Iterator<E> keySizes()
Returns an Iterator over the supported key sizes. Each element returned by this object is an Integer.
Specified by:
keySizes in interface IBlockCipher
keySizes in interface gnu.javax.crypto.cipher.IBlockCipherSpi
Returns:
an Iterator over the supported key sizes.

makeKey

public Object makeKey(byte[] k,
                      int bs)
            throws InvalidKeyException
Expands a user-supplied key material into a session key for a designated block size.
Specified by:
makeKey in interface gnu.javax.crypto.cipher.IBlockCipherSpi
Parameters:
k - the 64/128/192/256-bit user-key to use.
bs - the desired block size in bytes.
Returns:
an Object encapsulating the session key.
Throws:
IllegalArgumentException - if the block size is not 16 (128-bit).
InvalidKeyException - if the key data is invalid.

selfTest

public boolean selfTest()
A correctness test that consists of basic symmetric encryption / decryption test(s) for all supported block and key sizes, as well as one (1) variable key Known Answer Test (KAT).
Specified by:
selfTest in interface IBlockCipher
selfTest in interface gnu.javax.crypto.cipher.IBlockCipherSpi
Overrides:
selfTest in interface BaseCipher
Returns:
true if the implementation passes simple correctness tests. Returns false otherwise.

Twofish.java -- Copyright (C) 2001, 2002, 2003, 2006, 2010 Free Software Foundation, Inc. This file is a part of GNU Classpath. GNU Classpath is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. GNU Classpath is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNU Classpath; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA Linking this library statically or dynamically with other modules is making a combined work based on this library. Thus, the terms and conditions of the GNU General Public License cover the whole combination. As a special exception, the copyright holders of this library give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you may extend this exception to your version of the library, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version.