/**********************************************************\
|                                                          |
| The implementation of PHPRPC Protocol 3.0                |
|                                                          |
| xxtea.js                                                 |
|                                                          |
| Release 3.0.0                                            |
| Copyright (c) 2005-2008 by Team-PHPRPC                   |
|                                                          |
| WebSite:  http://www.phprpc.org/                         |
|           http://www.phprpc.net/                         |
|           http://www.phprpc.com/                         |
|           http://sourceforge.net/projects/php-rpc/       |
|                                                          |
| Authors:  Ma Bingyao <andot@ujn.edu.cn>                  |
|                                                          |
| This file may be distributed and/or modified under the   |
| terms of the GNU Lesser General Public License (LGPL)    |
| version 3.0 as published by the Free Software Foundation |
| and appearing in the included file LICENSE.              |
|                                                          |
\**********************************************************/

/* XXTEA encryption arithmetic library.
 *
 * Copyright (C) 2005-2008 Ma Bingyao <andot@ujn.edu.cn>
 * Version: 1.6
 * LastModified: May 6, 2007
 * This library is free.  You can redistribute it and/or modify it.
 */

// static class XXTEA
var XXTEA = new function() {
    // private static member delta
    var delta = 0x9E3779B9;

    // private static method longArrayToString
    function longArrayToString(data, includeLength) {
        var length = data.length;
        var n = (length - 1) << 2;
        if (includeLength) {
            var m = data[length - 1];
            if ((m < n - 3) || (m > n)) return null;
            n = m;
        }
        for (var i = 0; i < length; i++) {
            data[i] = String.fromCharCode(
                data[i] & 0xff,
                data[i] >>> 8 & 0xff,
                data[i] >>> 16 & 0xff, 
                data[i] >>> 24 & 0xff
            );
        }
        if (includeLength) {
            return data.join('').substring(0, n);
        }
        else {
            return data.join('');
        }
    }

    // private static method stringToLongArray
    function stringToLongArray(string, includeLength) {
        var length = string.length;
        var result = [];
        for (var i = 0; i < length; i += 4) {
            result[i >> 2] = string.charCodeAt(i) |
                string.charCodeAt(i + 1) << 8     |
                string.charCodeAt(i + 2) << 16    |
                string.charCodeAt(i + 3) << 24;
        }
        if (includeLength) {
            result[result.length] = length;
        }
        return result;
    }

    // public static method encrypt
    this.encrypt = function(string, key) {
        if (string == "") {
            return "";
        }
        var v = stringToLongArray(string, true);
        var k = stringToLongArray(key, false);
        if (k.length < 4) {
            k.length = 4;
        }
        var n = v.length - 1;

        var z = v[n], y = v[0];
        var mx, e, p, q = Math.floor(6 + 52 / (n + 1)), sum = 0;
        while (0 < q--) {
            sum = sum + delta & 0xffffffff;
            e = sum >>> 2 & 3;
            for (p = 0; p < n; p++) {
                y = v[p + 1];
                mx = (z >>> 5 ^ y << 2) + (y >>> 3 ^ z << 4) ^ (sum ^ y) + (k[p & 3 ^ e] ^ z);
                z = v[p] = v[p] + mx & 0xffffffff;
            }
            y = v[0];
            mx = (z >>> 5 ^ y << 2) + (y >>> 3 ^ z << 4) ^ (sum ^ y) + (k[p & 3 ^ e] ^ z);
            z = v[n] = v[n] + mx & 0xffffffff;
        }

        return longArrayToString(v, false);
    }

    // public static method decrypt
    this.decrypt = function(string, key) {
        if (string == "") {
            return "";
        }
        var v = stringToLongArray(string, false);
        var k = stringToLongArray(key, false);
        if (k.length < 4) {
            k.length = 4;
        }
        var n = v.length - 1;

        var z = v[n - 1], y = v[0];
        var mx, e, p, q = Math.floor(6 + 52 / (n + 1)), sum = q * delta & 0xffffffff;
        while (sum != 0) {
            e = sum >>> 2 & 3;
            for (p = n; p > 0; p--) {
                z = v[p - 1];
                mx = (z >>> 5 ^ y << 2) + (y >>> 3 ^ z << 4) ^ (sum ^ y) + (k[p & 3 ^ e] ^ z);
                y = v[p] = v[p] - mx & 0xffffffff;
            }
            z = v[n];
            mx = (z >>> 5 ^ y << 2) + (y >>> 3 ^ z << 4) ^ (sum ^ y) + (k[p & 3 ^ e] ^ z);
            y = v[0] = v[0] - mx & 0xffffffff;
            sum = sum - delta & 0xffffffff;
        }

        return longArrayToString(v, true);
    }
}