Backward private dynamic searchable encryption with update pattern

Symmetric Searchable Encryption (SSE) realizes to outsource data to an untrusted server privately. Dynamic SSE (DSSE) is a practical application which supports data addition and deletion. However, these update operations incur leakage during search and update queries. Therefore, forward and backward privacy were introduced to address the update and search operation leakage in DSSE. Forward privacy was extensively studied in the literature. Backward privacy with three types of revealing level was studied little. The strongest backward privacy was achieved by the expensive tools, impractical! Wheras the practical DSSEs gained weak backward privacy only. In this paper, we present a practical DSSE scheme to achieve stronger backward security—backward privacy with update pattern. We take advantage of key-homomorphic pseudorandom functions and our scheme requires only 1 roundtrip to get search result.