Achieving Practical Symmetric Searchable Encryption With Search Pattern Privacy Over Cloud

Dynamic symmetric searchable encryption (SSE), which enables a data user to securely search and dynamically update the encrypted documents stored in a semi-trusted cloud server, has received considerable attention in recent years. However, the search and update operations in many previously reported SSE schemes will bring some additional privacy leakages, e.g., search pattern privacy, forward privacy and backward privacy. To the best of our knowledge, none of the existing dynamic SSE schemes preserves the search pattern privacy, and many backward private SSE schemes still leak some critical information, e.g., the identifiers containing a specific keyword currently in the database. Therefore, aiming at the above challenges, in this article, we design a practical SSE scheme, which not only supports the search pattern privacy but also enhances the backward privacy. Specifically, we first leverage the k-anonymity and encryption to design an obfuscating technique. Then, based on the obfuscating technique, pseudorandom function and pseudorandom generator, we design a basic dynamic SSE scheme to support single keyword queries and simultaneously achieve search pattern privacy and enhanced backward privacy. Furthermore, we also extend our proposed scheme to support more efficient boolean queries. Security analysis demonstrates that our proposed scheme can achieve the desired privacy properties, and the extensive performance evaluations also show that our proposed scheme is indeed efficient in terms of communication overhead and computational cost.

Automated summary

Dynamic symmetric searchable encryption (SSE) enables secure search and dynamic update of encrypted documents in a semi-trusted cloud server. Existing SSE schemes have privacy leaks, and none of them can preserve search pattern privacy or enhance backward privacy. In this article, a practical SSE scheme is proposed, which supports search pattern privacy and enhances backward privacy through an obfuscating technique, pseudorandom function, and pseudorandom generator. Security analysis and performance evaluations demonstrate the effectiveness and efficiency of the proposed scheme.