Efficient Searchable Symmetric Encryption for Conjunctive Queries

OXT, which uses the Diffie-Hellman-type-operation-based secure two-party computation, is the state-of-the-art searchable symmetric encryption (SSE) scheme supporting conjunctive queries. However, the Diffie-Hellman-type operation is computationally expensive and may lead to a performance bottleneck. In order to improve the computational performance, an efficient searchable symmetric encryption scheme EXT which supports conjunctive queries is proposed. EXT uses a framework different from OXT to support conjunctive queries, where the client computes relations between keywords and documents independently, and the server only checks all these relations. Hence, no Diffie-Hellman operations are required for EXT. Furthermore, EXT is analyzed in terms of correctness, security, and performance. Compared with OXT, EXT reduces the setup computational cost, the client's computational cost, the server's computational cost, and the storage size by 95.05%, 97.67%, 98.48% and 55.05%, respectively.