private function getDirective()
    {
        switch (strtolower($this->type)) {
            case 'digest':
                return 'Digest ' . $this->buildDirectiveParameters(array(
                    'realm' => $this->realm,
                    'qop' => 'auth',
                    'nonce' => uniqid(),
                    'opaque' => md5($this->realm),
                ));

            default:
                return 'Basic ' . $this->buildDirectiveParameters(array(
                    'realm' => $this->realm
                ));
        }
    }