Android Byte Array Rotate unrotate(byte[] data, int blockSizeBytes)

Description

Unrotate data.

License

Open Source License

Parameter

Parameter	Description
data	a parameter
blockSizeBytes	a parameter

Declaration

public static byte[] unrotate(byte[] data, int blockSizeBytes) 

Method Source Code

//package com.java2s;
/*//w ww  .  j  a  va 2 s  .  c  o m
 * Copyright (c) 2010 Braiden Kindt
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use,
 * copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following
 * conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 *  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 *  OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 *  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 *  HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 *  WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 *  FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 *  OTHER DEALINGS IN THE SOFTWARE.
 *
 */

public class Main {
    /**
     * Unrotate data. Fpm interleaves data into muliple blocks
     * to ensure encrypted value always cahnges even if the 
     * first block is unchanged. 
     * 
     * @param data
     * @param blockSizeBytes
     * @return
     */
    public static byte[] unrotate(byte[] data, int blockSizeBytes) {
        byte result[] = new byte[data.length];

        int numBlocks = data.length / blockSizeBytes;

        for (int block = 0; block < numBlocks; block++) {
            for (int el = 0; el < blockSizeBytes; el++) {
                result[el * numBlocks + block] = data[block
                        * blockSizeBytes + el];
            }
        }

        return result;
    }
}

Related

1. rotateLeft(byte[] input)
2. rotateRight(byte[] input)