Quadcap Embeddable Database

com/quadcap/crypto/Tea256.java

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package com.quadcap.crypto;

/* Copyright 2002 - 2003 Quadcap Software.  All rights reserved.
 *
 * This software is distributed under the Quadcap Free Software License.
 * This software may be used or modified for any purpose, personal or
 * commercial.  Open Source redistributions are permitted.  Commercial
 * redistribution of larger works derived from, or works which bundle
 * this software requires a "Commercial Redistribution License"; see
 * http://www.quadcap.com/purchase.
 *
 * Redistributions qualify as "Open Source" under  one of the following terms:
 *   
 *    Redistributions are made at no charge beyond the reasonable cost of
 *    materials and delivery.
 *
 *    Redistributions are accompanied by a copy of the Source Code or by an
 *    irrevocable offer to provide a copy of the Source Code for up to three
 *    years at the cost of materials and delivery.  Such redistributions
 *    must allow further use, modification, and redistribution of the Source
 *    Code under substantially the same terms as this license.
 *
 * Redistributions of source code must retain the copyright notices as they
 * appear in each source code file, these license terms, and the
 * disclaimer/limitation of liability set forth as paragraph 6 below.
 *
 * Redistributions in binary form must reproduce this Copyright Notice,
 * these license terms, and the disclaimer/limitation of liability set
 * forth as paragraph 6 below, in the documentation and/or other materials
 * provided with the distribution.
 *
 * The Software is provided on an "AS IS" basis.  No warranty is
 * provided that the Software is free of defects, or fit for a
 * particular purpose.  
 *
 * Limitation of Liability. Quadcap Software shall not be liable
 * for any damages suffered by the Licensee or any third party resulting
 * from use of the Software.
 */

import java.util.Random;

import java.nio.ByteBuffer;
import java.nio.LongBuffer;

import com.quadcap.util.text.Text;
import com.quadcap.util.Util;

/**
 * Implementation of Tiny Encryption Algorithm, modified to use longs
 * instead of ints.  SO the key is now four longs, or 256 bits, and the
 * encryption/decryption proceeds 16 bytes at a time instead of 8.
 *
 * The number of rounds has been retained at 32.
 *
 * @author Stan Bailes
 */
public class Tea256 extends AbstractSymmetricKey implements SymmetricKey {
    /** Computed as (sqrt(5)-1) * 2**63, following original Tea choice of
        delta. */
    static final long delta = 0x9E3779B97F4A7C15L;
    static final int rounds = 32;
    
    long a, b, c, d;
    long[] v = new long[2];

    /**
     * Initialize key from serialized representation
     */
    public void init(String s) {
        String[] vx = Text.extractN(s, "*:*:*:*:*");
        a = Long.parseLong(vx[1]);
        b = Long.parseLong(vx[2]);
        c = Long.parseLong(vx[3]);
        d = Long.parseLong(vx[4]);
    }

    public void init(byte[] k) {
        a = Util.bytesToLong(k, 0);
        b = Util.bytesToLong(k, 8);
        c = Util.bytesToLong(k, 16);
        d = Util.bytesToLong(k, 24);
    }
    
    /**
     * Initialize: Create a random key
     */
    public void init(Random r) {
        a = r.nextLong();
        b = r.nextLong();
        c = r.nextLong();
        d = r.nextLong();
    }

    /**
     * Return the serialized form of the key
     */
    public String toString() {
        return "TEA256:" + a + ":" + b + ":" + c + ":" + d;
    }

    /**
     * Encrypt a buffer (must be multiple of 16 bytes)
     */
    public void encrypt(ByteBuffer plain, ByteBuffer code) {
        LongBuffer p = plain.asLongBuffer();
        LongBuffer cb = code.asLongBuffer();
        for (int i = 0; i < p.limit(); i += 2) {
            v[0] = p.get(i);
            v[1] = p.get(i+1);
            encrypt(v);
            cb.put(i, v[0]);
            cb.put(i+1, v[1]);
        }
    }

    /**
     * Decrypt a buffer (must be a multiple of 16 bytes)
     */
    public void decrypt(ByteBuffer code, ByteBuffer plain) {
        LongBuffer p = plain.asLongBuffer();
        LongBuffer cb = code.asLongBuffer();
        for (int i = 0; i < cb.limit(); i += 2) {
            v[0] = cb.get(i);
            v[1] = cb.get(i+1);
            decrypt(v);
            p.put(i, v[0]);
            p.put(i+1, v[1]);
        }
    }

    public int getBlockSize() { return 16; }
    
    final void encrypt(long[] v) {
        long y = v[0];
        long z = v[1];
        long sum = 0;
        
        for (int n = rounds; n-- > 0; ) {
            sum += delta;
            y += (z << 4) + a ^ z + sum ^ (z >>> 5) + b;
            z += (y << 4) + c ^ y + sum ^ (y >>> 5) + d;
        }
        v[0] = y;
        v[1] = z;
    }

    final void decrypt(long[] v) {
        long y = v[0];
        long z = v[1];
        long sum = delta * rounds;
        for (int n = rounds; n-- > 0; ) {
            z -= (y << 4) + c ^ y + sum ^ (y >>> 5) + d;
            y -= (z << 4) + a ^ z + sum ^ (z >>> 5) + b;
            sum -= delta;
        }
        v[0] = y;
        v[1] = z;
    }
}