Blockchain based searchable encryption for electronic health record sharing

Abstract Data leakage in electronic health records (EHRs) could result in the compromise of patient privacy (e.g. medical conditions). Generally most data in EHRs remain unchanged once they are uploaded to the system; thus, blockchain can be potentially used to facilitate the sharing of such data. Different participating medical organizations and individuals (e.g. medical practitioners, hospitals, medical labs and insurance companies) can then access EHRs stored on the blockchain with a higher level of confidence. In this paper, a blockchain based searchable encryption scheme for EHRs is proposed. The index for EHRs is constructed through complex logic expressions and stored in the blockchain, so that a data user can utilize the expressions to search the index. As only the index is migrated to the blockchain to facilitate propagation, the data owners have full control over who can see their EHRs data. The use of blockchain technology ensures the integrity, anti-tampering, and traceability of EHRs’ index. Finally, the performance of the proposed scheme is evaluated from two aspects, namely in terms of the overhead for extracting the document IDs from EHRs and the overhead associated with conducting transactions on smart contract in Ethereum.