Attribute Based Conjunctive Keywords Search With Verifiability and Fair Payment Using Blockchain

Cloud computing has brought great convenience to data storage and resource sharing, however, there are still concerns about data security and service quality. Attribute-based encryption (ABE) and searchable encryption (SE) are always adopted to achieve data access authorization and data retrieval on encrypted data in data sharing, respectively. But more efficient and accurate methods have been always pursued. Moreover, the spoofing attack is another important aspect that raises concerns, especially when it comes to reliability of search results and online payments. Blockchain, an emerging technology that can be used to solve the problem of trust, has shown great application potential in finance and data sharing. Based on blockchain, we propose an attribute-based conjunctive keyword search (ABCKS) scheme with verifiability and fairness. In this paper, data privacy-preserving, fine-grained access control, and multi-keywords search can be supported simultaneously. Blockchain and smart contract are employed to facilitate the search result verification process and ensure fair payment in the trustless case. Furthermore, we reduce the user's decryption load to a constant level by performing partial decryption on the cloud side. Finally, the results of the performance evaluation indicate that our scheme has higher efficiency and security.