Conjunctive Keywords Searchable Encryption Scheme Against Inside Keywords Guessing Attack from Lattice.

Public-key encryption with conjunctive keywords search (PECKS) is an extension of public-key encryption with keywords search (PEKS), which can realize the efficient search of the encrypted data stored in the cloud server and keep the privacy of these data during the search phase. However, there exists an inherent security issue for the typical PEKS schemes that they cannot prevent the inside keywords guessing attack (KGA). Moreover, most PEKS schemes were constructed based on the hardness of some number theory problems which can be solved in polynomial time using the quantum computer. Thus once large-scale quantum computers are built, these PEKS schemes aren’t secure in the future quantum era. To address the above issues, this paper proposes a lattice-based PECKS scheme which can resist inside KGA. Its security can be reduced to the hardness of LWE problem and ISIS problem, thus it can resist quantum computing attack. We also give a comparison with other searchable encryption schemes on the computational cost of the main algorithms and the size of related parameters.