de.flexiprovider.core.twofish
Class Twofish

java.lang.Object
  |
  +--javax.crypto.CipherSpi
        |
        +--de.flexiprovider.api.Cipher
              |
              +--de.flexiprovider.api.BlockCipher
                    |
                    +--de.flexiprovider.core.twofish.Twofish

public class Twofish

extends BlockCipher

This class implements the Twofish block cipher. For more information, see here. For more information about this implementation see: Diploma thesis "Implementierung von symmetrischen Verschluesselungsverfahren" by Katja Rauch. Twofish uses a block size of 16 bytes. The key size can be 128, 192, or 256 bits. Encryption/decryption takes 32 rounds.

Author:

Katja Rauch

Field Summary

static java.lang.String	ALG_NAME The algorithm name.
static int	blockSize The Twofish block size (16 bytes)

Fields inherited from class de.flexiprovider.api.BlockCipher

random

Fields inherited from class de.flexiprovider.api.Cipher

DECRYPT_MODE, ENCRYPT_MODE, opMode

Constructor Summary

Twofish()

Method Summary

int	getCipherBlockSize() This method returns the blocksize the algorithm uses.
int	getKeySize(Key key) Return the key size of the given key object.
java.lang.String	getName()
protected void	initCipherDecrypt(SecretKey key, AlgorithmParameterSpec params) Initialize the block cipher with a secret key for data encryption.
protected void	initCipherEncrypt(SecretKey key, AlgorithmParameterSpec params) Initializes the block cipher with a secret key for data encryption.
protected void	singleBlockDecrypt(byte[] input, int inOff, byte[] output, int outOff) This method decrypts a single block of data.
protected void	singleBlockEncrypt(byte[] input, int inOff, byte[] output, int outOff) This method encrypts a single block of data.

Methods inherited from class de.flexiprovider.api.BlockCipher

doFinal, doFinal, engineInit, getBlockSize, getIV, getOutputSize, getParameters, initDecrypt, initDecrypt, initDecrypt, initEncrypt, initEncrypt, initEncrypt, initEncrypt, setMode, setPadding, update, update

Methods inherited from class de.flexiprovider.api.Cipher

doFinal, doFinal, engineDoFinal, engineDoFinal, engineGetBlockSize, engineGetIV, engineGetKeySize, engineGetOutputSize, engineGetParameters, engineInit, engineInit, engineSetMode, engineSetPadding, engineUpdate, engineUpdate, update

Methods inherited from class java.lang.Object

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

Field Detail

ALG_NAME

public static final java.lang.String ALG_NAME

The algorithm name.

blockSize

public static final int blockSize

The Twofish block size (16 bytes)

Constructor Detail

Twofish

public Twofish()

Method Detail

getName

public java.lang.String getName()

Overrides:

getName in class Cipher

Returns:

the name of this cipher

getKeySize

public int getKeySize(Key key)
               throws InvalidKeyException

Return the key size of the given key object. Checks whether the key object is an instance of TwofishKey and whether the key size is within the specified range for Twofish. 128, 192, and 256 bit keys are allowed.

Overrides:

getKeySize in class Cipher

Parameters:

key - the key object

Returns:

the key size of the given key object.

Throws:

InvalidKeyException - if key is invalid.

getCipherBlockSize

public int getCipherBlockSize()

This method returns the blocksize the algorithm uses. It will be called by the padding scheme.

Overrides:

getCipherBlockSize in class BlockCipher

Returns:

the used blocksize in bytes

initCipherEncrypt

protected void initCipherEncrypt(SecretKey key,
                                 AlgorithmParameterSpec params)
                          throws InvalidKeyException

Initializes the block cipher with a secret key for data encryption. The algorithm parameters are not used.

Overrides:

initCipherEncrypt in class BlockCipher

Parameters:

key - the encryption key

params - the parameters (not used)

Throws:

InvalidKeyException - if the given key is null or not an instance of TwofishKey.

initCipherDecrypt

protected void initCipherDecrypt(SecretKey key,
                                 AlgorithmParameterSpec params)
                          throws InvalidKeyException

Initialize the block cipher with a secret key for data encryption. The algorithm parameters are not used.

Overrides:

initCipherDecrypt in class BlockCipher

Parameters:

key - the decryption key

params - the parameters (not used)

Throws:

InvalidKeyException - if the given key is null or not an instance of TwofishKey.

singleBlockEncrypt

protected void singleBlockEncrypt(byte[] input,
                                  int inOff,
                                  byte[] output,
                                  int outOff)

This method encrypts a single block of data. The array in must contain a whole block starting at inOffset and out must be large enough to hold an encrypted block starting at outOffset .

Overrides:

singleBlockEncrypt in class BlockCipher

Parameters:

input - array of bytes containing the plaintext to be encrypted

inOff - index in array in, where the plaintext block starts

output - array of bytes which will contain the ciphertext starting at outOffset

outOff - index in array out, where the ciphertext block will start

singleBlockDecrypt

protected void singleBlockDecrypt(byte[] input,
                                  int inOff,
                                  byte[] output,
                                  int outOff)

This method decrypts a single block of data. The array in must contain a whole block starting at inOffset and out must be large enough to hold an encrypted block starting at outOffset .

Overrides:

singleBlockDecrypt in class BlockCipher

Parameters:

input - array of bytes containig the ciphertext to be decrypted

inOff - index in array in, where the ciphertext block starts

output - array of bytes which will contain the plaintext starting at outOffset

outOff - index in array out, where the plaintext block will start