de.flexiprovider.core.rc5
Class RC5

java.lang.Object
  |
  +--javax.crypto.CipherSpi
        |
        +--de.flexiprovider.api.Cipher
              |
              +--de.flexiprovider.api.BlockCipher
                    |
                    +--de.flexiprovider.core.rc5.RC5

public class RC5

extends BlockCipher

This class implements the RC5 block-cipher algorithm according to the RFC 2040. RC5 was invented by Ronald Rivest for RSA Security in 1994. Further information can be found at RSA Security, in RFC 2040 and in the Handbook of Applied Cryptography, Menezes, van Oorschot, Vanstone, CRC Press, 1997, algorithm 7.115, 7.116 and 7.117.

The efficiency of this implementation has been tested on a AMD K6-III, 450 MHz, running Windows 2000 Prof., using jdk 1.2.2. The encryption/decryption rate is about 8.9 MBits / second using wordSize 32, rounds 12, keySize 16.

Author:

Oliver Seiler

Field Summary

static java.lang.String

ALG_NAME The algorithm name.

Fields inherited from class de.flexiprovider.api.BlockCipher

random

Fields inherited from class de.flexiprovider.api.Cipher

DECRYPT_MODE, ENCRYPT_MODE, opMode

Constructor Summary

RC5()

Method Summary

int	getCipherBlockSize() This method returns the block size, 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 block cipher the given key for data decryption.
protected void	initCipherEncrypt(SecretKey key, AlgorithmParameterSpec params) Initialize the block cipher with the given key for data encryption.
protected void	singleBlockDecrypt(byte[] in, int inOffset, byte[] out, int outOffset) This method decrypts a single block of data, and may only be called, when the block cipher is in decrytion mode.
protected void	singleBlockEncrypt(byte[] in, int inOffset, byte[] out, int outOffset) 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.

Constructor Detail

RC5

public RC5()

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 RC5Key or SecretKeySpec.

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()
                       throws java.lang.IllegalStateException

This method returns the block size, the algorithm uses. This method will usually be called by the padding scheme. Be sure not to call this before initializing the cipher.

Overrides:

getCipherBlockSize in class BlockCipher

Returns:

used block size in bytes

Throws:

java.lang.IllegalStateException - if called before initializing the cipher.

initCipherEncrypt

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

Initialize the block cipher with the given key for data encryption.

Overrides:

initCipherEncrypt in class BlockCipher

Parameters:

key - SecretKey to be used to encrypt data

params - AlgorithmParamterSpec to be used with this algorithm

Throws:

InvalidKeyException - if the given key is illegal for this cipher.

InvalidAlgorithmParameterException - if the given AlgorithmParameters are not appropriate for this cipher.

initCipherDecrypt

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

Initialize the block cipher the given key for data decryption.

Overrides:

initCipherDecrypt in class BlockCipher

Parameters:

key - SecretKey to be used to decrypt data

params - AlgorithmParamterSpec to be used with this algorithm

Throws:

InvalidKeyException - if the given key is illegal for this cipher

InvalidAlgorithmParameterException - if the given AlgorithmParameters are not appropriate for this cipher

singleBlockEncrypt

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

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 asured, too, that the array in contains a whole block starting at inOffset and that out is large enogh to hold an encrypted block starting at outOffset

Overrides:

singleBlockEncrypt in class BlockCipher

Parameters:

in - byte[] containing the plaintext to be encrypted starting at inOffset

inOffset - int index in the array in where the plaintext block starts

out - byte[] which will contain the ciphertext startig at outOffset

outOffset - int index in the array out where the ciphertext block will start

singleBlockDecrypt

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

This method decrypts a single block of data, and may only be called, when the block cipher is in decrytion mode. It has to be asured, too, that the array in contains a whole block starting at inOffset and that out is large enogh to hold an decrypted block starting at outOffset

Overrides:

singleBlockDecrypt in class BlockCipher

Parameters:

in - byte[] containing the ciphertext to be decrypted starting at inOffset

inOffset - int index in the array in where the ciphertext block starts

out - byte[] which will contain the plaintext startig at outOffset

outOffset - int index in the array out where the plaintext block will start