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/**
* CFB8Mode
*
* An ActionScript 3 implementation of the CFB-8 confidentiality mode
* Copyright (c) 2007 Henri Torgemane
*
* See LICENSE.txt for full license information.
*/
package com.hurlant.crypto.symmetric
{
import com.hurlant.crypto.tests.TestCase;
import flash.utils.ByteArray;
/**
*
* Note: The constructor accepts an optional padding argument, but ignores it otherwise.
*/
public class CFB8Mode extends IVMode implements IMode
{
public function CFB8Mode(key:ISymmetricKey, padding:IPad = null) {
super(key, null);
}
public function encrypt(src:ByteArray):void {
var vector:ByteArray = getIV4e();
var tmp:ByteArray = new ByteArray;
for (var i:uint=0;i<src.length;i++) {
tmp.position = 0;
tmp.writeBytes(vector);
key.encrypt(vector);
src[i] ^= vector[0];
// rotate
for (var j:uint=0;j<blockSize-1;j++) {
vector[j] = tmp[j+1];
}
vector[blockSize-1] = src[i];
}
}
public function decrypt(src:ByteArray):void {
var vector:ByteArray = getIV4d();
var tmp:ByteArray = new ByteArray;
for (var i:uint=0;i<src.length;i++) {
var c:uint = src[i];
tmp.position = 0;
tmp.writeBytes(vector); // I <- tmp
key.encrypt(vector); // O <- vector
src[i] ^= vector[0];
// rotate
for (var j:uint=0;j<blockSize-1;j++) {
vector[j] = tmp[j+1];
}
vector[blockSize-1] = c;
}
}
public function toString():String {
return key.toString()+"-cfb8";
}
}
}
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