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cryptix.jce.provider.cipher
Class TripleDES  

java.lang.Object
  javax.crypto.CipherSpi
      cryptix.jce.provider.cipher.BlockCipher
          cryptix.jce.provider.cipher.TripleDES

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public final class TripleDES

extends BlockCipher

This class implements Triple DES EDE encryption with three independent keys. DES-EDE3 acts as a block cipher with an 8 byte block size.

The encoded form of the Triple DES key should be a 24-byte array, consisting of three 8-byte single DES keys in order - K1, K2 and K3. Encryption and decryption are done as follows:

• C = E_K3(D_K2(E_K1(P)))
• P = D_K1(E_K2(D_K3(C)))

The alternating encryption and decryption was designed by IBM to enable compatibility with single DES, when all three keys are equal (although it is now rare for Triple DES to be used in that way).

When DES-EDE3 is used with the CBC mode class (algorithm name "DES-EDE3/CBC"), the result is Outer-CBC, and only one IV is used.

DES was written by IBM and first released in 1976. The algorithm is freely usable for both single and triple encryption.

Version:

$Revision: 1.7 $

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Field Summary
private static int	ALT_KEY_LENGTH
private static int	BLOCK_SIZE
private static int	DES_KEY_LENGTH
private  DES	des1
private  DES	des2
private  DES	des3
private static int	KEY_LENGTH

 

Fields inherited from class cryptix.jce.provider.cipher.BlockCipher

 

Constructor Summary

TripleDES()

 

Method Summary
protected  void	coreCrypt(byte[] in, int inOffset, byte[] out, int outOffset)           Perform a DES encryption or decryption operation (depends on subkey).
protected  void	coreInit(java.security.Key key, boolean decrypt)

 

Methods inherited from class cryptix.jce.provider.cipher.BlockCipher

clone, coreGetBlockSize, engineDoFinal, engineDoFinal, engineGetBlockSize, engineGetIV, engineGetKeySize, engineGetOutputSize, engineGetParameters, engineInit, engineInit, engineInit, engineSetMode, engineSetPadding, engineUpdate, engineUpdate

 

Methods inherited from class javax.crypto.CipherSpi

engineDoFinal, engineUnwrap, engineUpdate, engineWrap

 

Methods inherited from class java.lang.Object

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

 

Field Detail

BLOCK_SIZE

private static final int BLOCK_SIZE

See Also:

Constant Field Values

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KEY_LENGTH

private static final int KEY_LENGTH

See Also:

Constant Field Values

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ALT_KEY_LENGTH

private static final int ALT_KEY_LENGTH

See Also:

Constant Field Values

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DES_KEY_LENGTH

private static final int DES_KEY_LENGTH

See Also:

Constant Field Values

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des1

private DES des1

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des2

private DES des2

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des3

private DES des3

Constructor Detail

TripleDES

public TripleDES()

Method Detail

coreInit

protected void coreInit(java.security.Key key,
                        boolean decrypt)
                 throws java.security.InvalidKeyException

Specified by:

coreInit in class BlockCipher

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coreCrypt

protected void coreCrypt(byte[] in,
                         int inOffset,
                         byte[] out,
                         int outOffset)

Perform a DES encryption or decryption operation (depends on subkey).

Specified by:

coreCrypt in class BlockCipher

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