public function verify($response)
    {
        if (!$this->secretKey) {
            throw new Exception('Missing secret key');
        }

        $params = array(
            'secret' => $this->secretKey,
            'response' => $response,
        );

        if ($this->ip !== null) {
            $params['remoteip'] = $this->ip;
        }

        $this->httpClient->setUri(self::VERIFY_SERVER);
        $this->httpClient->setParameterPost($params);

        if ($this->options) {
            $this->httpClient->setOptions($this->options);
        }

        $this->httpClient->setMethod('POST');
        $response = $this->httpClient->send();

        return new CaptchaResponse($response);
    }