A Multi-User Dynamic Symmetric Searchable Encryption Scheme Supporting Conjunctive Search

In recent years, forward and backward security dynamic symmetric searchable encryption (DSSE) has attracted widespread attention, because it can against file injection attacks and restrict server learning information about deleted documents. However, most dynamic symmetric searchable encryption schemes that meet forward and backward security could only support single keyword search. In the NDSS 2021 conference, Patranabis et al. proposed a dynamic searchable encryption scheme that supported conjunctive keyword search and met forward and backward security. However, this scheme can not get accurate search results in some cases and can not support multi-user query, either. By improving the oblivious cross tags (OXT) protocol, a multi-user dynamic symmetric searchable encryption scheme that supports conjunctive keyword search is proposed. The scheme introduces a one-time blinding factor by using the property that the elements in the finite field have multiplicative inverse elements, and implements the function of multiple clients query combined with digital envelope technology. Scheme analysis and experiments show that the proposed scheme meets the forward security and backward security. It can not only provide accurate conjunctive keyword search function, but also support multi-user query, and the computation efficiency is only related to update times of the keyword with the lowest update times.