一种支持联合搜索的多用户动态对称可搜索加密方案

近年来，满足前后向安全的动态对称可搜索加密(dynamic symmetric searchable encryption, DSSE)一直备受关注，它可以抵抗文件注入攻击，同时限制服务器学习已删除文档的相关信息.不过大多数满足前后向安全的DSSE方案仅支持单关键词搜索，Patranabis等人在NDSS 2021会议上提出了一种支持联合搜索且满足前后向安全的动态可搜索加密方案，但该方案在某些情况下不能得到准确的查询结果，同时不能支持多用户查询.针对以上问题，通过改进不经意交叉索引(oblivious cross tags, OXT)协议，提出了一种支持联合搜索的多用户动态对称可搜索加密方案.该方案利用有限域中元素具有乘法逆元的性质，引入了一次性盲因子，并结合数字信封技术实现了多客户端查询的功能.方案分析与实验表明，所提方案满足了前向安全与后向安全，不仅可以提供准确的联合查询功能，而且支持多客户端查询，同时计算效率仅与更新次数最低的关键词更新次数有关.

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.