/**

 * 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;

		}

	}

}