Multi-user Searchable Encryption with Fine-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 or multi-user setting with coarser-grained access control. However, the application that multiple users with different access rights to the sharing data is more practical under the cloud environment. To bridge this gap, we consider searchable encryption with fine-grained access control under multi-user setting in this paper. The proposed scheme requires less computation cost at user side but provides fine-grained access control to authorized users under a new hybrid architecture. Combining symmetric encryption and Cipher text-Policy Attribute based Encryption(CP-ABE), we achieve a user collusion resistant scheme with the help of the private cloud. Our scheme solves a prevalent problem of key sharing. And the exposure of attribute secret key to the public cloud will not affect the system security. Dynamic and efficient user revocation is also provided. Security analysis shows that our scheme is secure.