/**
 * CFBMode
 * 
 * An ActionScript 3 implementation of the CFB confidentiality mode
 * Copyright (c) 2007 Henri Torgemane
 * 
 * See LICENSE.txt for full license information.
 */
package com.hurlant.crypto.symmetric
{
    import flash.utils.ByteArray;

    /**
     * This is the "full" CFB.
     * CFB1 and CFB8 are hiding somewhere else.
     * 
     * Note: The constructor accepts an optional padding argument, but ignores it otherwise.
     */
    public class CFBMode extends IVMode implements IMode
    {
        
        public function CFBMode(key:ISymmetricKey, padding:IPad = null) {
            super(key,null);
        }

        public function encrypt(src:ByteArray):void
        {
            var l:uint = src.length;
            var vector:ByteArray = getIV4e();
            for (var i:uint=0;i<src.length;i+=blockSize) {
                key.encrypt(vector);
                var chunk:uint = (i+blockSize<l)?blockSize:l-i;
                for (var j:uint=0;j<chunk;j++) {
                    src[i+j] ^= vector[j];
                }
                vector.position=0;
                vector.writeBytes(src, i, chunk);
            }
        }
        
        public function decrypt(src:ByteArray):void
        {
            var l:uint = src.length;
            var vector:ByteArray = getIV4d();
            var tmp:ByteArray = new ByteArray;
            for (var i:uint=0;i<src.length;i+=blockSize) {
                key.encrypt(vector);
                var chunk:uint = (i+blockSize<l)?blockSize:l-i;
                tmp.position=0;
                tmp.writeBytes(src, i, chunk);
                for (var j:uint=0;j<chunk;j++) {
                    src[i+j] ^= vector[j];
                }
                vector.position=0;
                vector.writeBytes(tmp);
            }
        }
        
        public function toString():String {
            return key.toString()+"-cfb";
        }

    }
}