**6. Conclusion**

In this chapter, a decentralized, Fog Computing, user authentication system was proposed for the development of a practical, low-cost, and general diagnosis system of the symptoms of PD patients using an Ethereum smart contract. It aimed to address user authentication in a decentralized environment and address fog computing security problems inherited from IoT and Cloud/Fog computing. It provided a solution for immutability and scale-ability problems in fog computing.

The system was simulated for validation and design using the simulation tools Cisco Packet Tracer, iFogSim, and Remix Ethereum. The obtained results proved the feasibility of the proposed system.

In future work, it is necessary to execute the process of building a fully functional system prototype involving real-based presented IoT devices connected to fog nodes equipped with Ethereum client to be connected with the real public Ethereum network, which is hosting the smart contract code. This makes it possible to complete a real diagnosis system of symptoms to support PD patients, necessary for the implementation of a real IoT health monitoring system that uses smartphones for data collection and machine learning algorithms for data processing.
