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;   }  }