Providing scalability and privacy for smart contract in the healthcare system.

As the healthcare industry evolved, it became an integral participant in providing services. In recent years, remote observation services have grown increasingly important for patients. In cases where patients are not physically present in clinics or hospitals, healthcare providers produce observations systems that diagnose and prescribe treatment. In/on patients' bodies, sensors are installed. Data can be exchanged wirelessly between healthcare systems. As a result of the implementation of blockchain-based characteristics (e.g. distributed ledger, decentralized storage, and authentication), healthcare systems can be enhanced. Accordingly, smart contracts are applied for the achievement of more authentication and sharing of records, and requirements for participants automatically. As the number of users or other components increases, blockchains and smart contracts should be able to provide quality service. Technically, smart contracts using blockchains have several challenges that are important, such as scalability, enhanced security, and optimal performance. There is still a question about the scalability of blockchain as there is a significant amount of computational power needed to scale up with a high number of participants in healthcare systems. In this paper, Hierarchical State Machines (HSMs) and ZoKrates are used to lower the consumption gas and the scalability of blockchain with smart contracts. [ABSTRACT FROM AUTHOR]