<?php
// File name:	encrypt.inc.php
// Description:	Extended PHP subroutine to encrypt/decrypt messages
// Date:	2003-08-19
// Author:	imacat <imacat@pristine.com.tw>
// Copyright:	Copyright (C) 2003-2007 Pristine Communications

// Settings
// This should be secret - need to be improved
define("ENCRYPT_KEY", base64_decode("MDJlMDI4MGYyZTZmN2I5ZDNlYTcyMzZiOGI5MzJlZmQ="));

// encrypt: Encrypt a message
function encrypt($s)
{
    $s = strlen($s) . " " . $s;
    // Pad with spaces
    $s = str_pad($s, 32 * ceil(strlen($s) / 32));
    // Obtain the IV
    $iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_ECB);
    $iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);
    return base64_encode(mcrypt_encrypt(MCRYPT_RIJNDAEL_256, ENCRYPT_KEY, $s, MCRYPT_MODE_ECB, $iv));
}

// decrypt: Decrypt a message
function decrypt($s)
{
    // Obtain the IV
    $iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_ECB);
    $iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);
    $s = mcrypt_decrypt(MCRYPT_RIJNDAEL_256, ENCRYPT_KEY, base64_decode($s), MCRYPT_MODE_ECB, $iv);
    // Not returning a good formatted decoded text
    if (!preg_match("/^(\d+) /", $s, $m)) {
        return null;
    }
    $len = $m[1];
    $s = preg_replace("/^(\d+) /", "", $s);
    return substr($s, 0, $len);
}

?>