Privacy-Enhanced Dynamic Symmetric Searchable Encryption with Efficient Searches Under Sparse Keywords

Dynamic Searchable Symmetric Encryption (DSSE) enables users to search and update an encrypted database stored on a semi-honest server. It preserves the confidentiality of the data. Currently, many works focus on achieving forward and backward privacy and efficiency performance. However, in sparse keywords scenarios, a large document collection consists of a small number of distinct keywords, it is still challenging to design DSSE schemes that achieve both high security and practical performance. To address these issues, we propose a scheme called SGsse-F, which satisfies forward update privacy (FuP) and weak forward search privacy (FsP), and a scheme named SGsse-FB that satisfies FuP, weak FsP and TYPE-II backward privacy (BP). Both schemes employ partitioning technique, hash and pseudo-random functions to construct encryption entities and effectively support parallel keyword search. Experimental results demonstrate that the SGsse-F and SGsse-FB schemes exhibit better search performance compared to Dual, Mitra, FSSE and FSSE*. Additionally, the client storage for both schemes is suitable.