/flash-src/third-party/com/hurlant/crypto/symmetric/PKCS5.as

 1/**
 2 * PKCS5
 3 * 
 4 * A padding implementation of PKCS5.
 5 * Copyright (c) 2007 Henri Torgemane
 6 * 
 7 * See LICENSE.txt for full license information.
 8 */
 9package com.hurlant.crypto.symmetric
10{
11	import flash.utils.ByteArray;
12	
13	public class PKCS5 implements IPad
14	{
15		private var blockSize:uint;
16		
17		public function PKCS5(blockSize:uint=0) {
18			this.blockSize = blockSize;
19		}
20		
21		public function pad(a:ByteArray):void {
22			var c:uint = blockSize-a.length%blockSize;
23			for (var i:uint=0;i<c;i++){
24				a[a.length] = c;
25			}
26		}
27		public function unpad(a:ByteArray):void {
28			var c:uint = a.length%blockSize;
29			if (c!=0) throw new Error("PKCS#5::unpad: ByteArray.length isn't a multiple of the blockSize");
30			c = a[a.length-1];
31			for (var i:uint=c;i>0;i--) {
32				var v:uint = a[a.length-1];
33				a.length--;
34				if (c!=v) throw new Error("PKCS#5:unpad: Invalid padding value. expected ["+c+"], found ["+v+"]");
35			}
36			// that is all.
37		}
38
39		public function setBlockSize(bs:uint):void {
40			blockSize = bs;
41		}
42
43	}
44}