Blockchain-Based Secure and Searchable EHR Sharing Scheme

Electronic Health Record (EHR) not only contains great value, but also implies a large amount of personal privacy. Aiming at the security problems such as data forgery and tampering in EHR data sharing process, this paper proposes a blockchain-based EHR data searchable scheme to realize the calculation and application of EHR data in the decentralized network environment. This paper stores the EHR data ciphertext on the cloud, and stores the keyword index of the EHR data on the blockchain. The data visitor's search result on the blockchain is only the blind value of the data identifier, and is generated after blinding. The token for downloading ciphertext data in the cloud not only improves storage efficiency of the system, but also ensures the integrity, immutability and traceability of the EHR data index. Based on the attribute encryption mechanism, the fine-grained access control of cloud data is realized, and the attribute signature technology is used to verify the authenticity of the EHR data source. Finally, experiments show that the encryption and search time of this scheme is constant, regardless of the number of attributes.