/** * OFBMode * * An ActionScript 3 implementation of the OFB confidentiality mode * Copyright (c) 2007 Henri Torgemane * * See LICENSE.txt for full license information. */ package com.hurlant.crypto.symmetric { import flash.utils.ByteArray; public class OFBMode extends IVMode implements IMode { public function OFBMode(key:ISymmetricKey, padding:IPad=null) { super(key, null); } public function encrypt(src:ByteArray):void { var vector:ByteArray = getIV4e(); core(src, vector); } public function decrypt(src:ByteArray):void { var vector:ByteArray = getIV4d(); core(src, vector); } private function core(src:ByteArray, iv:ByteArray):void { var l:uint = src.length; var tmp:ByteArray = new ByteArray; for (var i:uint=0;i<src.length;i+=blockSize) { key.encrypt(iv); tmp.position=0; tmp.writeBytes(iv); var chunk:uint = (i+blockSize<l)?blockSize:l-i; for (var j:uint=0;j<chunk;j++) { src[i+j] ^= iv[j]; } iv.position=0; iv.writeBytes(tmp); } } public function toString():String { return key.toString()+"-ofb"; } } }