Quadcap Embeddable Database

com/quadcap/crypto/Tea.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.IntBuffer;

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

/**
 * Implementation of Tiny Encryption Algorithm
 *
 * @author Stan Bailes
 */
public class Tea extends AbstractSymmetricKey implements SymmetricKey {
    static final int delta     = 0x9E3779B9;
    int a, b, c, d;
    int[] v = new int[2];

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

    public void init(byte[] k) {
        a = Util.integer(k, 0);
        b = Util.integer(k, 4);
        c = Util.integer(k, 8);
        d = Util.integer(k, 12);
    }

    /**
     * Initialize: Create a random key
     */
    public void init(Random r) {
        a = r.nextInt();
        b = r.nextInt();
        c = r.nextInt();
        d = r.nextInt();
    }

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

    /**
     * Encrypt a buffer (must be multiple of 8 bytes)
     */
    public void encrypt(ByteBuffer m, ByteBuffer c) {
        while (m.position() < m.limit()) {
            v[0] = m.getInt();
            v[1] = m.getInt();
            encrypt(v);
            c.putInt(v[0]);
            c.putInt(v[1]);
        }
    }

    /**
     * Decrypt a buffer (must be a multiple of 8 bytes)
     */
    public void decrypt(ByteBuffer c, ByteBuffer m) {
        while ( c.position() < c.limit()) {
            v[0] = c.getInt();
            v[1] = c.getInt();
            decrypt(v);
            m.putInt(v[0]);
            m.putInt(v[1]);
        }
    }

    public int getBlockSize() { return 8; }
    
    final void encrypt(int[] v) {
        int y = v[0];
        int z = v[1];
        int sum = 0;
        
        for (int n = 32; 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(int[] v) {
        int y = v[0];
        int z = v[1];
        int sum = 0xC6EF3720;
        for (int n = 32; 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;
    }
}