Achieving authorized and ranked multi-keyword search over encrypted cloud data

In cloud computing, it is important to protect user data. Thus, data owners usually encrypt their data before outsourcing them to the cloud server for security and privacy concerns. At the same time, very often users need to find data for specific keywords of interest to them. This motivates the research on the searchable encryption technique, which allows the search user to search over the encrypted data. Many mechanisms have been proposed, and are mainly focusing on the symmetric searchable encryption (SSE) technique. However, they do not consider the search authorization problem that requires the cloud server only to return the search results to authorized users. In this paper, we propose an authorized and ranked multi-keyword search scheme (ARMS) over encrypted cloud data by leveraging the ciphertext policy attribute-based encryption (CP-ABE) and SSE techniques. Security analysis demonstrates that the proposed ARMS scheme can achieve confidentiality of documents, trapdoor unlinkability and collusion resistance. Extensive experiments show that the ARMS is more superior and efficient than existing approaches in terms of functionalities and computational overhead.