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/**
* CTRMode
*
* An ActionScript 3 implementation of the counter 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 CTRMode extends IVMode implements IMode
{
public function CTRMode(key:ISymmetricKey, padding:IPad = null) {
super(key, padding);
}
public function encrypt(src:ByteArray):void
{
padding.pad(src);
var vector:ByteArray = getIV4e();
core(src, vector);
}
public function decrypt(src:ByteArray):void
{
var vector:ByteArray = getIV4d();
core(src, vector);
padding.unpad(src);
}
private function core(src:ByteArray, iv:ByteArray):void {
var X:ByteArray = new ByteArray;
var Xenc:ByteArray = new ByteArray;
X.writeBytes(iv);
for (var i:uint=0;i<src.length;i+=blockSize) {
Xenc.position=0;
Xenc.writeBytes(X);
key.encrypt(Xenc);
for (var j:uint=0;j<blockSize;j++) {
src[i+j] ^= Xenc[j];
}
for (j=blockSize-1;j>=0;--j) {
X[j]++;
if (X[j]!=0)
break;
}
}
}
public function toString():String {
return key.toString()+"-ctr";
}
}
}
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