de.flexiprovider.core.desede
Class DESede

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

Direct Known Subclasses:

DESede.DESede_CBC

public class DESede

extends BlockCipher

This class implements the TripleDES (DESede) block cipher. The implementation conforms to the FIPS 46-3 standard.

Note that the single DES algorithm can be emulated by TripleDES by concatenating the same key three times.

Author:

Norbert Trummel, Sylvain Franke, Torsten Ehli, Oliver Seiler

Inner Class Summary

static class

DESede.DESede_CBC DESede_CBC

Field Summary

static java.lang.String	ALG_NAME The algorithm name.
static int	blockSize The DESede block size (8 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

DESede()

Method Summary

int	getCipherBlockSize() Return the blocksize the algorithm uses.
int	getKeySize(Key key) Returns the key size of the given key object.
java.lang.String	getName()
protected void	initCipherDecrypt(SecretKey key, AlgorithmParameterSpec params) Initialize the cipher for decryption.
protected void	initCipherEncrypt(SecretKey key, AlgorithmParameterSpec params) Initialize the cipher for encryption.
protected void	singleBlockDecrypt(byte[] input, int inOff, byte[] output, int outOff) This method decrypts a single block of data, and may only be called, when the block cipher is in decryption mode.
protected void	singleBlockEncrypt(byte[] input, int inOff, byte[] output, int outOff) This method encrypts a single block of data, and may only be called, when the block cipher is in encrytion mode.

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 DESede block size (8 bytes)

Constructor Detail

DESede

public DESede()

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

Returns the key size of the given key object. Checks whether the key object is an instance of DESedeKey or SecretKeySpec. If the 3 DES keys differ from each other, the effective key strength is 112 bits (not 168 bits, due to a meet in the middle attack), if they are all equal, we're simulating single DES.

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()

Return the blocksize the algorithm uses. This method will usually 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

Initialize the cipher for encryption.

Overrides:

initCipherEncrypt in class BlockCipher

Parameters:

key - the secret key used for encryption

params - algorithm parameters (not used)

Throws:

InvalidKeyException - if the given key is inappropriate for initializing this cipher.

initCipherDecrypt

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

Initialize the cipher for decryption.

Overrides:

initCipherDecrypt in class BlockCipher

Parameters:

key - the secret key used for decryption

params - algorithm parameters (not used)

Throws:

InvalidKeyException - if the given key is inappropriate for initializing this cipher.

singleBlockEncrypt

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

This method encrypts a single block of data, and may only be called, when the block cipher is in encrytion mode. It has to be assured, too, that the array in contains a whole block starting at inOffset and that out is large enough to hold an encrypted block starting at outOffset. Key schedule is according to the FIPS46.3 standard.

Overrides:

singleBlockEncrypt in class BlockCipher

Parameters:

input - array of bytes which contains 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, and may only be called, when the block cipher is in decryption mode. It has to be assured, too, that the array in contains a whole block starting at inOffset and that out is large enough to hold a decrypted block starting at outOffset. Key schedule is according to the FIPS46.3 standard.

Overrides:

singleBlockDecrypt in class BlockCipher

Parameters:

input - array of bytes which contains 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