private function check_signature($consumerkey, $secret, $body) {

        $ok = true;
        try {
            // TODO: Switch to core oauthlib once implemented - MDL-30149.
            lti\handle_oauth_body_post($consumerkey, $secret, $body);
        } catch (\Exception $e) {
            debugging($e->getMessage() . "\n");
            $ok = false;
        }

        return $ok;

    }