A Blockchain and CP-ABE Based Access Control Scheme with Fine-Grained Revocation of Attributes in Cloud Health

The Access control scheme is an effective method to protect user data privacy. The access control scheme based on blockchain and ciphertext policy attribute encryption (CP–ABE) can solve the problems of single—point of failure and lack of trust in the centralized system. However, it also brings new problems to the health information in the cloud storage environment, such as attribute leakage, low consensus efficiency, complex permission updates, and so on. This paper proposes an access control scheme with fine-grained attribute revocation, keyword search, and traceability of the attribute private key distribution process. Blockchain technology tracks the authorization of attribute private keys. The credit scoring method improves the Raft protocol in consensus efficiency. Besides, the interplanetary file system (IPFS) addresses the capacity deficit of blockchain. Under the premise of hiding policy, the research proposes a fine-grained access control method based on users, user attributes, and file structure. It optimizes the data-sharing mode. At the same time, Proxy Re-Encryption (PRE) technology is used to update the access rights. The proposed scheme proved to be secure. Comparative analysis and experimental results show that the proposed scheme has higher efficiency and more functions. It can meet the needs of medical institutions.