php5.5中有更为可靠和方便的加密方式。喜欢钻研的朋友可以了解一下：

passWord_hash()

http://www.php.net/manual/zh/function.password-hash.php

基于mcrypt扩展，按位异或总结的两个字符串加密解密算法

<?php/** * @info 字符串加密解密算法一,利用mcrypt扩展 * @param string $string 待处理字符串 *        $action ENCODE,加密 | DECODE，解密 * @return string $returnstr * @date 2014/4/22 * @author tonglei */function mcrypt_handle_string($string, $action = 'ENCODE'){        !is_array($string) or exit;        $action == 'DECODE' && $string = base64_decode($string);        $key = "123456"; //key可自定义或在配置文件中获取        $mcryptAlgorithm = MCRYPT_DES; //选择一种加密算法        $mcryptMode = MCRYPT_MODE_ECB; //选择一种加密模式        $mcryptIv = mcrypt_create_iv(mcrypt_get_iv_size($mcryptAlgorithm, $mcryptMode),                MCRYPT_RAND); //创建初始化向量        $returnstr = base64_encode(mcrypt_encrypt($mcryptAlgorithm, $key, $string, $mcryptMode,                $mcryptIv));        if('DECODE' == $action)        {                $returnstr = mcrypt_decrypt($mcryptAlgorithm, $key, $string, $mcryptMode, $mcryptIv);        }        return $returnstr;}

<?php/** * * @info 字符串加密解密算法二 利用按位异或 * @param string $string 待处理字符串 * @param $action ENCODE 加密 | DECODE 解密 * @return string */function StrCode($string, $action = 'ENCODE'){        $action != 'ENCODE' && $string = base64_decode($string);        $code = '';        $key = substr(md5($GLOBALS['pwServer']['HTTP_USER_AGENT'] . $GLOBALS['db_hash']),                8, 18);        $keyLen = strlen($key);        $strLen = strlen($string);        for ($i = 0; $i < $strLen; $i++)        {                $k = $i % $keyLen;                $code .= $string[$i] ^ $key[$k];        }        return ($action != 'DECODE' ? base64_encode($code) : $code);}