php加密解密處理類--參 考：Discuz論壇的passpor

<?php

02 /*=========================================================== 03 = 版權協議： 04 = GPL (The GNU GENERAL PUBLIC LICENSE Version 2, June 1991) 05 =------------------------------------------------------------ 06 = 文件名稱：cls.sys_crypt.php 07 = 摘    要：php加密解密處理類 08 = 版    本：1.0 09 = 參    考：Discuz論壇的passport相關函數 10 =------------------------------------------------------------ 11 = Script Written By PHPWMS項目組 12 = 最後更新：xinge 13 = 最後日期：2007-12-09 14 ============================================================*/ 15   16 class SysCrypt { 17   18 private $crypt_key; 19   20 // 構造函數 21 public function __construct($crypt_key) { 22    $this -> crypt_key = $crypt_key; 23 } 24   25 public function php_encrypt($txt) { 26    srand((double)microtime() * 1000000); 27    $encrypt_key = md5(rand(0,32000)); 28    $ctr = 0; 29    $tmp = ''; 30    for($i = 0;$i<strlen($txt);$i++) { 31     $ctr = $ctr == strlen($encrypt_key) ? 0 : $ctr; 32     $tmp .= $encrypt_key[$ctr].($txt[$i]^$encrypt_key[$ctr++]); 33    } 34    return base64_encode(self::__key($tmp,$this -> crypt_key)); 35 } 36   37 public function php_decrypt($txt) { 38    $txt = self::__key(b