connectbot/sshlib

package com.trilead.ssh2.crypto.cipher;

/*
 * This file was shamelessly taken (and modified) from the Bouncy Castle Crypto package.
 * Their licence file states the following:
 *
 * Copyright (c) 2000 - 2004 The Legion Of The Bouncy Castle
 * (http://www.bouncycastle.org)
 *
 * 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.
 */

/**
 * DESede.
 *
 * @author See comments in the source file
 * @version $Id: DESede.java,v 1.1 2007/10/15 12:49:55 cplattne Exp $
 *
 */
public class DESede extends DES
{
    private int[] key1 = null;
    private int[] key2 = null;
    private int[] key3 = null;

    private boolean encrypt;

    /**
     * standard constructor.
     */
    public DESede()
    {
    }

    /**
     * initialise a DES cipher.
     *
     * @param encrypting
     *            whether or not we are for encryption.
     * @param key
     *            the parameters required to set up the cipher.
     * @exception IllegalArgumentException
     *                if the params argument is inappropriate.
     */
    @Override
    public void init(boolean encrypting, byte[] key, byte[] iv)
    {
        key1 = generateWorkingKey(encrypting, key, 0);
        key2 = generateWorkingKey(!encrypting, key, 8);
        key3 = generateWorkingKey(encrypting, key, 16);

        encrypt = encrypting;
    }

    public String getAlgorithmName()
    {
        return "DESede";
    }

    @Override
    public void transformBlock(byte[] in, int inOff, byte[] out, int outOff)
    {
        if (key1 == null)
        {
            throw new IllegalStateException("DESede engine not initialised!");
        }

        if (encrypt)
        {
            desFunc(key1, in, inOff, out, outOff);
            desFunc(key2, out, outOff, out, outOff);
            desFunc(key3, out, outOff, out, outOff);
        }
        else
        {
            desFunc(key3, in, inOff, out, outOff);
            desFunc(key2, out, outOff, out, outOff);
            desFunc(key1, out, outOff, out, outOff);
        }
    }

    private abstract static class Wrapper implements BlockCipher {
        protected BlockCipher bc;

        @Override
        public int getBlockSize() {
            return bc.getBlockSize();
        }

        @Override
        public void transformBlock(byte[] src, int srcoff, byte[] dst, int dstoff) {
            bc.transformBlock(src, srcoff, dst, dstoff);
        }
    }

    public static class CBC extends Wrapper {
        @Override
        public void init(boolean forEncryption, byte[] key, byte[] iv) throws IllegalArgumentException {
            BlockCipher rawCipher = new DESede();
            rawCipher.init(forEncryption, key, iv);
            bc = new CBCMode(rawCipher, iv, forEncryption);
        }
    }

    public static class CTR extends Wrapper {
        @Override
        public void init(boolean forEncryption, byte[] key, byte[] iv) throws IllegalArgumentException {
            BlockCipher rawCipher = new DESede();
            rawCipher.init(true, key, iv);
            bc = new CTRMode(rawCipher, iv, forEncryption);
        }
    }
}