public function getAttachUrl($params = [], $cookieBased = null)
    {
        $this->generateToken($cookieBased);

        $data = [
            'command' => 'attach',
            'broker' => $this->broker,
            'token' => $this->token,
            'checksum' => hash('sha256', 'attach' . $this->token . $this->secret)
        ] + $_GET;

        return $this->url . "?" . http_build_query($data + $params);
    }