/js/lib/Socket.IO-node/support/socket.io-client/lib/vendor/web-socket-js/flash-src/com/hurlant/crypto/prng/ARC4.as

/**

 * ARC4

 * 

 * An ActionScript 3 implementation of RC4

 * Copyright (c) 2007 Henri Torgemane

 * 

 * Derived from:

 * 		The jsbn library, Copyright (c) 2003-2005 Tom Wu

 * 

 * See LICENSE.txt for full license information.

 */

package com.hurlant.crypto.prng

{

	import com.hurlant.crypto.symmetric.IStreamCipher;

	import com.hurlant.util.Memory;

	

	import flash.utils.ByteArray;



	public class ARC4 implements IPRNG, IStreamCipher {

		private var i:int = 0;

		private var j:int = 0;

		private var S:ByteArray;

		private const psize:uint = 256;

		public function ARC4(key:ByteArray = null){

			S = new ByteArray;

			if (key) {

				init(key);

			}

		}

		public function getPoolSize():uint {

			return psize;

		}

		public function init(key:ByteArray):void {

			var i:int;

			var j:int;

			var t:int;

			for (i=0; i<256; ++i) {

				S[i] = i;

			}

			j=0;

			for (i=0; i<256; ++i) {

				j = (j + S[i] + key[i%key.length]) & 255;

				t = S[i];

				S[i] = S[j];

				S[j] = t;

			}

			this.i=0;

			this.j=0;

		}

		public function next():uint {

			var t:int;

			i = (i+1)&255;

			j = (j+S[i])&255;

			t = S[i];

			S[i] = S[j];

			S[j] = t;

			return S[(t+S[i])&255];

		}



		public function getBlockSize():uint {

			return 1;

		}

		

		public function encrypt(block:ByteArray):void {

			var i:uint = 0;

			while (i<block.length) {

				block[i++] ^= next();

			}

		}

		public function decrypt(block:ByteArray):void {

			encrypt(block); // the beauty of XOR.

		}

		public function dispose():void {

			var i:uint = 0;

			if (S!=null) {

				for (i=0;i<S.length;i++) {

					S[i] = Math.random()*256;

				}

				S.length=0;

				S = null;

			}

			this.i = 0;

			this.j = 0;

			Memory.gc();

		}

		public function toString():String {

			return "rc4";

		}

	}

}