cryptix.provider.cipher
Class DES2X

java.lang.Object
  xjava.security.IJCE_Traceable
      xjava.security.Cipher
          cryptix.provider.cipher.DES2X

All Implemented Interfaces:

Parameterized, SymmetricCipher

public class DES2X

extends Cipher

implements SymmetricCipher

This class implements DES2X encryption with four independent keys. DES2X acts as a block cipher with an 8 byte block size.

The encoded form of the DESX key should be a 32-byte array, consisting of one 8-byte DES key K and three XOR keys K1, K2 and K3 in order - K, K1, K2 and K3. Encryption and decryption are done as follows:

• C = E(E(P XOR K1) XOR K2) XOR K3
• P = D(D(C XOR K3) XOR K2) XOR K1

When DES2X is used with the CBC mode class (algorithm name "DES2X/CBC"), the result is Outer-CBC, and only one IV is used.

References:

1. Bruce Schneier, "Chapter 12 Data Encryption Standard," and "Section 15.2 Triple Encryption," Applied Cryptography, 2nd edition, John Wiley & Sons, 1996

2. R.C. Merkle and M. Hellman, "On the Security of Multiple Encryption," Communications of the ACM, vol. 24 no. 7, 1981, pages 465-467.

3. P Karn, P Metzger, W A Simpson "The ESP Triple DES Transform," Internet Draft, draft-simpson-esp-des3-x-01.txt

Copyright © 1998 Systemics Ltd on behalf of the Cryptix Development Team.
All rights reserved.

$Revision: 1.3 $

Since:

Cryptix 3.0.4

Author:

Sascha Kettler

Field Summary

Fields inherited from class xjava.security.Cipher

DECRYPT, ENCRYPT, UNINITIALIZED

Constructor Summary

DES2X()
Constructs a DES2X cipher object, in the UNINITIALIZED state.

Method Summary

int	engineBlockSize() SPI: Returns the length of an input block, in bytes.
protected void	engineInitDecrypt(java.security.Key key) SPI: Initializes this cipher for decryption, using the specified key.
void	engineInitEncrypt(java.security.Key key) SPI: Initializes this cipher for encryption, using the specified key.
protected int	engineUpdate(byte[] in, int inOffset, int inLen, byte[] out, int outOffset) SPI: This is the main engine method for updating data.

Methods inherited from class xjava.security.Cipher

blockSize, clone, crypt, crypt, crypt, doFinal, doFinal, doFinal, doFinal, engineCiphertextBlockSize, engineCrypt, engineGetParameter, engineInBufferSize, engineOutBufferSize, enginePlaintextBlockSize, engineSetPaddingScheme, engineSetParameter, getAlgorithm, getAlgorithms, getAlgorithms, getCiphertextBlockSize, getInputBlockSize, getInstance, getInstance, getInstance, getMode, getOutputBlockSize, getPadding, getPaddingScheme, getParameter, getPlaintextBlockSize, getProvider, getState, inBufferSize, inBufferSizeFinal, initDecrypt, initEncrypt, isPaddingBlockCipher, outBufferSize, outBufferSizeFinal, setParameter, toString, update, update, update, update

Methods inherited from class java.lang.Object

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

Constructor Detail

DES2X

public DES2X()

Constructs a DES2X cipher object, in the UNINITIALIZED state. This calls the Cipher constructor with implBuffering false, implPadding false and the provider set to "Cryptix".

Method Detail

engineBlockSize

public int engineBlockSize()

SPI: Returns the length of an input block, in bytes.

Overrides:

engineBlockSize in class Cipher

Returns:

the length in bytes of an input block for this cipher.

engineInitEncrypt

public void engineInitEncrypt(java.security.Key key)
                       throws java.security.KeyException

SPI: Initializes this cipher for encryption, using the specified key.

Specified by:

engineInitEncrypt in class Cipher

Parameters:

key - the key to use for encryption.

Throws:

java.security.KeyException - if one of the following occurs:

• key.getEncoded() == null;
• The length of the user key array is invalid.

engineInitDecrypt

protected void engineInitDecrypt(java.security.Key key)
                          throws java.security.KeyException

SPI: Initializes this cipher for decryption, using the specified key.

Specified by:

engineInitDecrypt in class Cipher

Parameters:

key - the key to use for decryption.

Throws:

java.security.KeyException - if one of the following occurs:

• key.getEncoded() == null;
• The length of the user key array is invalid.

engineUpdate

protected int engineUpdate(byte[] in,
                           int inOffset,
                           int inLen,
                           byte[] out,
                           int outOffset)

SPI: This is the main engine method for updating data.

in and out may be the same array, and the input and output regions may overlap.

Specified by:

engineUpdate in class Cipher

Parameters:

in - the input data.

inOffset - the offset into in specifying where the data starts.

inLen - the length of the subarray.

out - the output array.

outOffset - the offset indicating where to start writing into the out array.

Returns:

the number of bytes written.

Throws:

CryptixException - if the native library is being used, and it reports an error.