A Cloud Data Access Authorization Update Scheme Based on Blockchain

In order to better realize the storage and sharing of data in the cloud and ensure the validity of data privacy and access authorization, this paper proposes a cloud data access authorization update scheme based on Blockchain, which supports keyword retrieval. Firstly, the risk of collusion attack is effectively reduced by using ciphertext storage separately. Secondly, the method of splitting and managing the proxy re-encryption key parameters can achieve the purpose of deterministic authority update only when the access authority changes and only needs to update the key parameter management. In addition, the scheme alleviates the amount of computation of users during data sharing and the pressure of high-frequency access of cloud storage. Through security analysis, the scheme is safe under the ciphertext attack. Finally, a numerical simulation is given to verify the efficiency of the scheme algorithm.