A Blockchain-Based Fine-Grained Access Data Control Scheme With Attribute Change Function

A distributed storage system (DSS) has the ad-vantages of low price and high throughput, but it also raises serious data confidentiality and privacy issues. Fine-grained access control (AC) is important for further applications. Although attribute-based encryption (ABE) schemes can achieve fine-grained AC, almost all schemes distribute a private key to a visitor by a private key generator that may leak data. Besides, attribute revocation functions of the ABE scheme will lead to collusion attacks. Blockchain-based ABE schemes rarely consider ciphertext-based search and attribute revocation functions which lead to a large communication overhead. In this paper, we propose a secure ABE scheme in which a data owner is the only person who has the right to distribute keys. Then we combine blockchain with the proposed ABE scheme to realize fine-grained AC over a distributed storage system, which supports the attribute change function and resists collusive attacks. In addition, we build a series of smart contracts to ensure the fairness of trade between the data owner and visitor. The auxiliary information of data stored on the blockchain can realize ciphertext-based search. Finally, we prove the scheme resists collusion attacks under the computational Diffie-Hellman assumption (CDH) and conduct multiple experiments based on Ethernet test Network. The experimental results demonstrate our scheme has the running time of algorithms reached a millisecond-level and the ET H cost is acceptable.