Duo\Web::verifyResponse PHP Метод

    public static function verifyResponse($ikey, $skey, $akey, $sig_response, $time = null)
    {
        list($auth_sig, $app_sig) = explode(':', $sig_response);
        $auth_user = self::parseVals($skey, $auth_sig, self::AUTH_PREFIX, $ikey, $time);
        $app_user = self::parseVals($akey, $app_sig, self::APP_PREFIX, $ikey, $time);
        if ($auth_user !== $app_user) {
            return null;
        }
        return $auth_user;
    }

 public function testFutureResponseInvalidIkey()
 {
     $wrong_ikey = "DIXXXXXXXXXXXXXXXXXY";
     $this->assertEquals(\Duo\Web::verifyResponse($wrong_ikey, self::SKEY, self::AKEY, $this->valid_future_response . ":" . $this->valid_app_sig), null);
 }