org.bouncycastle.crypto.engines
Class HC256Engine

java.lang.Object
  org.bouncycastle.crypto.engines.HC256Engine

All Implemented Interfaces:

StreamCipher

public class HC256Engine
extends java.lang.Object
implements StreamCipher

HC-256 is a software-efficient stream cipher created by Hongjun Wu. It generates keystream from a 256-bit secret key and a 256-bit initialization vector.

http://www.ecrypt.eu.org/stream/p3ciphers/hc/hc256_p3.pdf

Its brother, HC-128, is a third phase candidate in the eStream contest. The algorithm is patent-free. No attacks are known as of today (April 2007). See http://www.ecrypt.eu.org/stream/hcp3.html

Field Summary

private byte[]	buf
private int	cnt
private int	idx
private boolean	initialised
private byte[]	iv
private byte[]	key
private int[]	p
private int[]	q

Constructor Summary

HC256Engine()

Method Summary

java.lang.String	getAlgorithmName() Return the name of the algorithm the cipher implements.
private byte	getByte()
private void	init()
void	init(boolean forEncryption, CipherParameters params) Initialise a HC-256 cipher.
void	processBytes(byte[] in, int inOff, int len, byte[] out, int outOff) process a block of bytes from in putting the result into out.
void	reset() reset the cipher.
byte	returnByte(byte in) encrypt/decrypt a single byte returning the result.
private static int	rotateRight(int x, int bits)
private int	step()

Methods inherited from class java.lang.Object

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

Field Detail

p

private int[] p

q

private int[] q

cnt

private int cnt

key

private byte[] key

iv

private byte[] iv

initialised

private boolean initialised

buf

private byte[] buf

idx

private int idx

Constructor Detail

HC256Engine

public HC256Engine()

Method Detail

step

private int step()

init

private void init()

getAlgorithmName

public java.lang.String getAlgorithmName()

Description copied from interface: StreamCipher

Return the name of the algorithm the cipher implements.

Specified by:

getAlgorithmName in interface StreamCipher

Returns:

the name of the algorithm the cipher implements.

init

public void init(boolean forEncryption,
                 CipherParameters params)
          throws java.lang.IllegalArgumentException

Initialise a HC-256 cipher.

Specified by:

init in interface StreamCipher

Parameters:

forEncryption - whether or not we are for encryption. Irrelevant, as encryption and decryption are the same.

params - the parameters required to set up the cipher.

Throws:

java.lang.IllegalArgumentException - if the params argument is inappropriate (ie. the key is not 256 bit long).

getByte

private byte getByte()

processBytes

public void processBytes(byte[] in,
                         int inOff,
                         int len,
                         byte[] out,
                         int outOff)
                  throws DataLengthException

Description copied from interface: StreamCipher

process a block of bytes from in putting the result into out.

Specified by:

processBytes in interface StreamCipher

Parameters:

in - the input byte array.

inOff - the offset into the in array where the data to be processed starts.

len - the number of bytes to be processed.

out - the output buffer the processed bytes go into.

outOff - the offset into the output byte array the processed data starts at.

Throws:

DataLengthException - if the output buffer is too small.

reset

public void reset()

Description copied from interface: StreamCipher

reset the cipher. This leaves it in the same state it was at after the last init (if there was one).

Specified by:

reset in interface StreamCipher

returnByte

public byte returnByte(byte in)

Description copied from interface: StreamCipher

encrypt/decrypt a single byte returning the result.

Specified by:

returnByte in interface StreamCipher

Parameters:

in - the byte to be processed.

Returns:

the result of processing the input byte.

rotateRight

private static int rotateRight(int x,
                               int bits)