/**

 * PKCS5

 * 

 * A padding implementation of PKCS5.

 * Copyright (c) 2007 Henri Torgemane

 * 

 * See LICENSE.txt for full license information.

 */

package com.hurlant.crypto.symmetric

{

	import flash.utils.ByteArray;

	

	public class PKCS5 implements IPad

	{

		private var blockSize:uint;

		

		public function PKCS5(blockSize:uint=0) {

			this.blockSize = blockSize;

		}

		

		public function pad(a:ByteArray):void {

			var c:uint = blockSize-a.length%blockSize;

			for (var i:uint=0;i<c;i++){

				a[a.length] = c;

			}

		}

		public function unpad(a:ByteArray):void {

			var c:uint = a.length%blockSize;

			if (c!=0) throw new Error("PKCS#5::unpad: ByteArray.length isn't a multiple of the blockSize");

			c = a[a.length-1];

			for (var i:uint=c;i>0;i--) {

				var v:uint = a[a.length-1];

				a.length--;

				if (c!=v) throw new Error("PKCS#5:unpad: Invalid padding value. expected ["+c+"], found ["+v+"]");

			}

			// that is all.

		}



		public function setBlockSize(bs:uint):void {

			blockSize = bs;

		}



	}

}