/**
 * TLSPad
 * 
 * A padding implementation used by TLS
 * Copyright (c) 2007 Henri Torgemane
 * 
 * See LICENSE.txt for full license information.
 */
package com.hurlant.crypto.symmetric {
    import flash.utils.ByteArray;
    import com.hurlant.util.Hex;
    import com.hurlant.crypto.tls.TLSError;
    
    public class TLSPad implements IPad {
        private var blockSize:uint;
        
        public function TLSPad(blockSize:uint=0) {
            this.blockSize = blockSize;
        }
        public function pad(a:ByteArray):void {
            var c:uint = blockSize - (a.length+1)%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 TLSError("TLSPad::unpad: ByteArray.length isn't a multiple of the blockSize", TLSError.bad_record_mac);
            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 TLSError("TLSPad:unpad: Invalid padding value. expected ["+c+"], found ["+v+"]", TLSError.bad_record_mac);
            }
            a.length--;
            // mostly ripped off from PKCS5.as, but with subtle differences
        }
        public function setBlockSize(bs:uint):void {
            blockSize = bs;
        }
    }
}