protected function baseProtocolParameters()
    {
        $dateTime = new \DateTime();

        return array(
            'oauth_consumer_key' => $this->clientCredentials->getIdentifier(),
            'oauth_nonce' => $this->nonce(),
            'oauth_signature_method' => $this->signature->method(),
            'oauth_timestamp' => $dateTime->format('U'),
            'oauth_version' => '1.0',
        );
    }