gnu.crypto.prng

Class ARCFour

java.lang.Object

gnu.crypto.prng.BasePRNG

gnu.crypto.prng.ARCFour

All Implemented Interfaces:

IRandom, Cloneable

public class ARCFour
extends BasePRNG

RC4 is a stream cipher developed by Ron Rivest. Until 1994 RC4 was a trade secret of RSA Data Security, Inc., when it was released anonymously to a mailing list. This version is a descendent of that code, and since there is no proof that the leaked version was in fact RC4 and because "RC4" is a trademark, it is called "ARCFOUR", short for "Allegedly RC4".

This class only implements the keystream of ARCFOUR. To use this as a stream cipher, one would say:

    out = in ^ arcfour.nextByte();

This operation works for encryption and decryption.

References:

1. Schneier, Bruce: Applied Cryptography: Protocols, Algorithms, and Source Code in C, Second Edition. (1996 John Wiley and Sons), pp. 397--398. ISBN 0-471-11709-9
2. K. Kaukonen and R. Thayer, "A Stream Cipher Encryption Algorithm 'Arcfour'", Internet Draft (expired), draft-kaukonen-cipher-arcfour-03.txt

Version:

$Revision: 1.2 $

Field Summary

Fields

Modifier and Type	Field and Description
static String	ARCFOUR_KEY_MATERIAL The attributes property name for the key bytes.
static int	ARCFOUR_SBOX_SIZE The size of the internal S-box.

Fields inherited from class gnu.crypto.prng.BasePRNG

buffer, initialised, name, ndx

Constructor Summary

Constructors

Constructor and Description
ARCFour() Default 0-arguments constructor.

Method Summary

Modifier and Type	Method and Description
Object	clone() Returns a clone copy of this instance.
void	fillBlock()
void	setup(Map attributes)

Methods inherited from class gnu.crypto.prng.BasePRNG

init, isInitialised, name, nextByte, nextBytes

Methods inherited from class java.lang.Object

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

Field Detail

ARCFOUR_KEY_MATERIAL

public static final String ARCFOUR_KEY_MATERIAL

The attributes property name for the key bytes.

See Also:

Constant Field Values

ARCFOUR_SBOX_SIZE

public static final int ARCFOUR_SBOX_SIZE

The size of the internal S-box.

See Also:

Constant Field Values

Constructor Detail

ARCFour

public ARCFour()

Default 0-arguments constructor.

Method Detail

clone

public Object clone()

Description copied from interface: IRandom

Returns a clone copy of this instance.

Specified by:

clone in interface IRandom

Specified by:

clone in class BasePRNG

Returns:

a clone copy of this instance.

setup

public void setup(Map attributes)

Specified by:

setup in class BasePRNG

fillBlock

public void fillBlock()
               throws LimitReachedException

Specified by:

fillBlock in class BasePRNG

Throws:

LimitReachedException