strlen($decrypted)) {        return false;    }    if(strspn($decrypted, chr($pad), strlen($decrypted) - $pad) != $pad) {        return false;    }    $result = substr($decrypted, 0, -1 * $pad);    $result = mb_convert_encoding($result, 'UTF-8', 'GBK');    return $result;}?>