def enroll(self):
        """Enrollment function"""
        self.verify_integrity()

        if session.get('u2f_enroll_authorized', False):
            if request.method == 'GET':
                return jsonify(self.get_enroll()), 200

            elif request.method == 'POST':
                response = self.verify_enroll(request.json)

                if response['status'] == 'ok':
                    return jsonify(response), 201
                else:
                    return jsonify(response), 400

        return jsonify({'status': 'failed', 'error': 'Unauthorized!'}), 401