/**
 * 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;
        }

    }
}