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/**
* 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";
}
}
}
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