Efficient publicly verifiable conjunctive keyword search over encrypted data in cloud computing

Cloud computing has brought many appealing features for its users, such as on-demand computing resources, flexible and ubiquitous access and economical cost. Individuals and enterprises are motivated to outsource mass data to the cloud server. However, the privacy and security of the users' data are the main obstacles preventing the application of cloud computing. Searchable encryption technique is a positive way to protect users' sensitive data, while preserving search ability over encrypted data on the server side. However, the cloud server may be lazy and return part of the search results to its users as a result of intending to relieve their workload. Therefore, a verification mechanism should be established to guarantee the correctness and completeness of the search results. In this paper, we present an efficient publicly verifiable keyword search scheme over encrypted data. Our scheme achieves the conjunctive keyword search and ensures the correctness and completeness of the search results even if the untrusted cloud server returns an empty set deliberately. Compared with existing conjunctive keyword search schemes, our scheme is more efficient in the aspect of verifying the search results. Furthermore, we prove that the proposed scheme can achieve the desired security properties.