Multi-user Searchable Encryption with Coarser-Grained Access Control without Key Sharing

Searchable encryption(SE) schemes allow users to perform keyword search on encrypted data without leakage of the sensitive information. Most of the existing SE schemes are limited to single-user setting where a user acts as both the data owner and the data retriever. However, the data-sharing environment drives multiple users to access the same data sets. To bridge this gap, we consider searchable encryption under multi-user setting in this paper. We focus on tackling the challenge of dynamical user injection and revocation by maintaining a complementary key list in the public cloud. Furthermore, a method based on key relevance to solve the problem of key sharing is present here. Our scheme achieves coarser-grained access control in hybrid cloud, and security analysis shows that our scheme is secure.