Abstract:

For the problem of secure storage and credible sharing of massive data, a data sharing access control method of cloud-chain collaboration is proposed. Firstly, the system model based on blockchain and cloud storage is constructed. The attribute encryption algorithm based on ciphertext policy is improved, and the user-attribute many-to-many association policy is established to realize the access control of data ciphertext and solve the problem of honest and curious cloud servers. Then, an effective public key that supports both fine-grained access control and multi-keyword search of encrypted data is proposed. The proposed method is proved to be secure under the assumptions of deterministic Diffie-Hellman and stochastic Oracle models, and the experimental results show that the proposed method is more efficient in the index generation and keyword matching stages.

Key words: Cloud server, block chain, searchable encryption, properties of encryption, access control