Privacy-Preserving Blockchain-Based Healthcare System for IoT Devices Using zk-SNARK

Privacy is playing a crucial role in the smart health industry, where health service providers and their customers use the internet of things (IoT) to provide and consume health services. Preserving privacy for legitimate users and preventing illegitimate users from accessing services are difficult to implement simultaneously. In this study, we addressed this issue by proposing a new healthcare system for IoT based on the blockchain and zero-knowledge succinct noninteractive argument of knowledge (zk-SNARK). We employ the anonymity property of the public blockchain to protect users’ privacy. The zk-SNARK scheme works as an anonymous authenticator to prevent unauthorized users from using services. We also analyze the security of the proposed system by showing that it can resist various types of attacks, such as impersonation, collusion, and man-in-the-middle attacks. Finally, we evaluate the performance of the zk-SNARK scheme with respect to computational costs and the interactions with the Ethereum blockchain smart contract with respect to transaction fees.