<?php
/**********************************************************\
|                                                          |
| The implementation of PHPRPC Protocol 3.0                |
|                                                          |
| xxtea.php                                                |
|                                                          |
| Release 3.0.1                                            |
| Copyright 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 General Public License (GPL) version    |
| 2.0 as published by the Free Software Foundation and     |
| appearing in the included file LICENSE.                  |
|                                                          |
\**********************************************************/

/* XXTEA encryption arithmetic library.
 *
 * Copyright: Ma Bingyao <andot@ujn.edu.cn>
 * Version: 1.6
 * LastModified: Apr 12, 2010
 * This library is free.  You can redistribute it and/or modify it under GPL.
 */
function long2str($v, $w)
{
    $len = count($v);
    $n = ($len - 1) << 2;
    if ($w) {
        $m = $v[$len - 1];
        if (($m < $n - 3) || ($m > $n)) return false;
        $n = $m;
    }
    $s = array();
    for ($i = 0; $i < $len; $i++)
    {
        $s[$i] = pack("V", $v[$i]);
    }

    if ($w)
    {
        return substr(join('', $s), 0, $n);
    }
    else
    {
        return join('', $s);
    }
}

function str2long($s, $w)
{
    $v = unpack("V*", $s. str_repeat("\0", (4 - strlen($s) % 4) & 3));
    $v = array_values($v);
    if ($w)
    {
        $v[count($v)] = strlen($s);
    }
    return $v;
}

function int32($n)
{
    while ($n >= 2147483648) $n -= 4294967296;
    while ($n <= -2147483649) $n += 4294967296;
    return (int)$n;
}

function xxtea_encrypt($str, $key)
{
    if ($str == "")
    {
        return "";
    }
    $v = str2long($str, true);
    $k = str2long($key, false);
    if (count($k) < 4)
    {
        for ($i = count($k); $i < 4; $i++) {
            $k[$i] = 0;
        }
    }
    $n = count($v) - 1;

    $z = $v[$n];
    $y = $v[0];
    $delta = 0x9E3779B9;
    $q = floor(6 + 52 / ($n + 1));
    $sum = 0;
    while (0 < $q--)
    {
        $sum = int32($sum + $delta);
        $e = $sum >> 2 & 3;
        for ($p = 0; $p < $n; $p++)
        {
            $y = $v[$p + 1];
            $mx = int32((($z >> 5 & 0x07ffffff) ^ $y << 2) + (($y >> 3 & 0x1fffffff) ^ $z << 4)) ^ int32(($sum ^ $y) + ($k[$p & 3 ^ $e] ^ $z));
            $z = $v[$p] = int32($v[$p] + $mx);
        }
        $y = $v[0];
        $mx = int32((($z >> 5 & 0x07ffffff) ^ $y << 2) + (($y >> 3 & 0x1fffffff) ^ $z << 4)) ^ int32(($sum ^ $y) + ($k[$p & 3 ^ $e] ^ $z));
        $z = $v[$n] = int32($v[$n] + $mx);
    }
    return long2str($v, false);
}

function xxtea_decrypt($str, $key)
{
    if ($str == "")
    {
        return "";
    }
    $v = str2long($str, false);
    $k = str2long($key, false);
    if (count($k) < 4)
    {
        for ($i = count($k); $i < 4; $i++) {
            $k[$i] = 0;
        }
    }
    $n = count($v) - 1;

    $z = $v[$n];
    $y = $v[0];
    $delta = 0x9E3779B9;
    $q = floor(6 + 52 / ($n + 1));
    $sum = int32($q * $delta);
    while ($sum != 0)
    {
        $e = $sum >> 2 & 3;
        for ($p = $n; $p > 0; $p--)
        {
            $z = $v[$p - 1];
            $mx = int32((($z >> 5 & 0x07ffffff) ^ $y << 2) + (($y >> 3 & 0x1fffffff) ^ $z << 4)) ^ int32(($sum ^ $y) + ($k[$p & 3 ^ $e] ^ $z));
            $y = $v[$p] = int32($v[$p] - $mx);
        }
        $z   = $v[$n];
        $mx  = int32((($z >> 5 & 0x07ffffff) ^ $y << 2) + (($y >> 3 & 0x1fffffff) ^ $z << 4)) ^ int32(($sum ^ $y) + ($k[$p & 3 ^ $e] ^ $z));
        $y   = $v[0] = int32($v[0] - $mx);
        $sum = int32($sum - $delta);
    }
    return long2str($v, true);
}