No abstract

Electronic health record (EHR) allows patients to use an open channel (ie, Internet) to control, share and manage their health records among family members, healthcare providers and other third party data users. Thus, in such an environment, privacy, confidentiality, and data consistency are the major challenges. Although cloud‐based EHR addresses the aforementioned discussions, these are prone to various malicious attacks, trust management and non‐repudiation among servers. Recently, due to the property of immutability, blockchain technology has been introduced to be as an auspicious solution for achieving EHR sharing with privacy and security preservation. Motivated by the above debates, we present BFHS, a blockchain‐based fine‐grained secure EHR sharing mechanism. On BFHS, we encrypt the EHR using ciphertext‐policy attribute‐based encryption (CP‐ABE) and upload it to the interplanetary file system (IPFS) for storage, while the matching index is encrypted via proxy re‐encryption and kept in a medical consortium blockchain. In addition, we created a credit assessment mechanism and incorporated it into the smart contract. Smart contracts, proxy re‐encryption, a credit evaluation mechanism, and IPFS all work together to give patients with a trustworthy EHR sharing environment and a dynamic access control interface. The thorough comparison and experimental analysis show that the proposed BFHS has more comprehensive security features and is more practicable.

With the fantastic development of cloud computing technology, cloud storage has been widely applied in the field of medical data sharing due to its efficiency and flexibility. Attribute-based encryption (ABE), as a promising technology, plays an important role in the fine-grained sharing of medical data. However, there are two issues: (1) an access policy specified in the encryption phase may need to be updated after a period of time, and (2) the considerable decryption overhead in ABE is too heavy for resource-limited devices. To address these issues, a fine-grained medical data sharing scheme with ciphertext reencryption is proposed. Users with decryption permission can produce reencryption keys and cloud server can reencrypt initial ciphertext. The cloud server can predecrypt ciphertext, which reduces user’s decryption overhead. Moreover, the traditional centralized server is replaced with a decentralized blockchain that performs system initialization, key management, and user revocation. We compared the proposed scheme with some existing schemes in terms of function and efficiency; the results show that the efficiency of the proposed scheme outperforms other related schemes. The security analysis shows that the proposed scheme is security and correctness.