Hierarchical Cloud-Based Consortium Blockchains for Healthcare Data Storage

Blockchain technology can be used as a healthcare solution that allows hospitals to store and share electronic health records (EHRs) in a secure and reliable manner. However, the number of hospitals that can participate in a blockchain network is limited by the inclusion of big data such as multimedia files, which presents an obvious scalability problem. In this paper, we introduce a hierarchical cloud-based consortium blockchain framework for storing big data including multimedia files within cloud-based local hospital blockchain networks and sharing them with hospitals outside the networks through high-level blockchain networks, called city blockchain networks and state blockchain network. We present procedures for concurrently searching EHRs, creating access control policies for authorized access, and retrieving EHRs through hierarchical blockchain networks. The experimental results show that our approach is feasible and efficient for accessing and sharing EHRs using hierarchical cloud-based consortium blockchains throughout a country.