org.bouncycastle.crypto.engines
Class RC532Engine

java.lang.Object
  org.bouncycastle.crypto.engines.RC532Engine

All Implemented Interfaces:

BlockCipher

public class RC532Engine
extends java.lang.Object
implements BlockCipher

The specification for RC5 came from the RC5 Encryption Algorithm publication in RSA CryptoBytes, Spring of 1995. http://www.rsasecurity.com/rsalabs/cryptobytes.

This implementation has a word size of 32 bits.

Implementation courtesy of Tito Pena.

Field Summary

private int	_noRounds
private int[]	_S
private boolean	forEncryption
private static int	P32
private static int	Q32

Constructor Summary

RC532Engine()
Create an instance of the RC5 encryption algorithm and set some defaults

Method Summary

private int	bytesToWord(byte[] src, int srcOff)
private int	decryptBlock(byte[] in, int inOff, byte[] out, int outOff)
private int	encryptBlock(byte[] in, int inOff, byte[] out, int outOff) Encrypt the given block starting at the given offset and place the result in the provided buffer starting at the given offset.
java.lang.String	getAlgorithmName() Return the name of the algorithm the cipher implements.
int	getBlockSize() Return the block size for this cipher (in bytes).
void	init(boolean forEncryption, CipherParameters params) initialise a RC5-32 cipher.
int	processBlock(byte[] in, int inOff, byte[] out, int outOff) Process one block of input from the array in and write it to the out array.
void	reset() Reset the cipher.
private int	rotateLeft(int x, int y) Perform a left "spin" of the word.
private int	rotateRight(int x, int y) Perform a right "spin" of the word.
private void	setKey(byte[] key) Re-key the cipher.
private void	wordToBytes(int word, byte[] dst, int dstOff)

Methods inherited from class java.lang.Object

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

Field Detail

_noRounds

private int _noRounds

_S

private int[] _S

P32

private static final int P32

See Also:

Constant Field Values

Q32

private static final int Q32

See Also:

Constant Field Values

forEncryption

private boolean forEncryption

Constructor Detail

RC532Engine

public RC532Engine()

Create an instance of the RC5 encryption algorithm and set some defaults

Method Detail

getAlgorithmName

public java.lang.String getAlgorithmName()

Description copied from interface: BlockCipher

Return the name of the algorithm the cipher implements.

Specified by:

getAlgorithmName in interface BlockCipher

Returns:

the name of the algorithm the cipher implements.

getBlockSize

public int getBlockSize()

Description copied from interface: BlockCipher

Return the block size for this cipher (in bytes).

Specified by:

getBlockSize in interface BlockCipher

Returns:

the block size for this cipher in bytes.

init

public void init(boolean forEncryption,
                 CipherParameters params)

initialise a RC5-32 cipher.

Specified by:

init in interface BlockCipher

Parameters:

forEncryption - whether or not we are for encryption.

params - the parameters required to set up the cipher.

Throws:

java.lang.IllegalArgumentException - if the params argument is inappropriate.

processBlock

public int processBlock(byte[] in,
                        int inOff,
                        byte[] out,
                        int outOff)

Description copied from interface: BlockCipher

Process one block of input from the array in and write it to the out array.

Specified by:

processBlock in interface BlockCipher

Parameters:

in - the array containing the input data.

inOff - offset into the in array the data starts at.

out - the array the output data will be copied into.

outOff - the offset into the out array the output will start at.

Returns:

the number of bytes processed and produced.

reset

public void reset()

Description copied from interface: BlockCipher

Reset the cipher. After resetting the cipher is in the same state as it was after the last init (if there was one).

Specified by:

reset in interface BlockCipher

setKey

private void setKey(byte[] key)

Re-key the cipher.

Parameters:

key - the key to be used

encryptBlock

private int encryptBlock(byte[] in,
                         int inOff,
                         byte[] out,
                         int outOff)

Encrypt the given block starting at the given offset and place the result in the provided buffer starting at the given offset.

Parameters:

in - in byte buffer containing data to encrypt

inOff - offset into src buffer

out - out buffer where encrypted data is written

outOff - offset into out buffer

decryptBlock

private int decryptBlock(byte[] in,
                         int inOff,
                         byte[] out,
                         int outOff)

rotateLeft

private int rotateLeft(int x,
                       int y)

Perform a left "spin" of the word. The rotation of the given word x is rotated left by y bits. Only the lg(32) low-order bits of y are used to determine the rotation amount. Here it is assumed that the wordsize used is a power of 2.

Parameters:

x - word to rotate

y - number of bits to rotate % 32

rotateRight

private int rotateRight(int x,
                        int y)

Perform a right "spin" of the word. The rotation of the given word x is rotated left by y bits. Only the lg(32) low-order bits of y are used to determine the rotation amount. Here it is assumed that the wordsize used is a power of 2.

Parameters:

x - word to rotate

y - number of bits to rotate % 32

bytesToWord

private int bytesToWord(byte[] src,
                        int srcOff)

wordToBytes

private void wordToBytes(int word,
                         byte[] dst,
                         int dstOff)