강력한 PHP 암호화 및 복호화 클래스

http://blog.ddian.cn/?post=923

class Ender{
    private $enkey;//加密解密用的密钥
    //构造参数是密钥
    public function __construct($key=''){
        if(!$key){
            $this->enkey=$key;
        }
    }
    //设置密钥
    public function set_key($key){
        $this->enkey=$key;
    }
    private function keyED($txt,$encrypt_key)
    {
    $encrypt_key = md5($encrypt_key);
    $ctr=0;
    $tmp = "";
    for ($i=0;$i    {
    if ($ctr==strlen($encrypt_key)) $ctr=0;
    $tmp.= substr($txt,$i,1) ^ substr($encrypt_key,$ctr,1);
    $ctr  ;
    }
    return $tmp;
    }
    //加密字符串
    public function encrypt($txt,$key='')
    {
    if(!$key){
            $key=$this->enkey;
        }
    srand((double)microtime()*1000000);
    $encrypt_key = md5(rand(0,32000));
    $ctr=0;
    $tmp = "";
    for ($i=0;$i    {
    if ($ctr==strlen($encrypt_key)) $ctr=0;
    $tmp.= substr($encrypt_key,$ctr,1) .
    (substr($txt,$i,1) ^ substr($encrypt_key,$ctr,1));
    $ctr  ;
    }
    return base64_encode($this->keyED($tmp,$key));
    }
    //解密字符串
    public function decrypt($txt,$key='')
    {
    $txt=base64_decode($txt);
    if(!$key){
            $key=$this->enkey;
        }
    $txt = $this->keyED($txt,$key);
    $tmp = "";
    for ($i=0;$i    {
    $md5 = substr($txt,$i,1);
    $i  ;
    $tmp.= (substr($txt,$i,1) ^ $md5);
    }
    return $tmp; //http://blog.ddian.cn
    }

}