HierChain: A Hierarchical-Blockchain-Based Data Management System for Smart Healthcare

Healthcare is a crucial element of human lives that produces a substantial amount of medical data every year. A major difficulty faced by e-Health systems is the secure storage and sharing of this data without compromising its integrity and privacy. Being a trustless, traceable, and immutable technology, blockchain has the potential to address these issues. In this article, we propose HierChain, a hierarchical block chain-based data storage and sharing system for healthcare. This framework provides a trustless environment that is decentralized and tamper-resistant for efficient management of data. We first introduce an optimization problem aimed at identifying the optimal data storage solution for maximum efficiency. Next, we classify the health data based on its specific features, sensitivity, and storage requirements. This classified data is then stored on three different blockchains (Ethereum, Hyperledger Sawtooth, and MultiChain) according to their optimal attributes. We utilize fog nodes for providing computational services to the resource-constrained Internet of Things (IoT) nodes, enabling us to perform data preprocessing and eliminate redundant information from the collected data. Moreover, we use differential privacy on the fog layer to ensure that sensitive medical data remains protected throughout the analysis process. Finally, we present a comprehensive attack evaluation and performance analysis by implementing our framework on a real-world medical data set. The simulation results indicate that HierChain outperforms existing algorithms in terms of scalability and security of health data without degrading the performance of the IoT network.