Practical Multi-User Dynamic Searchable Symmetric Encryption With Hierarchical Authorization
Beining Wang, Jing Chen, Kun He, Bei Shen, Sicheng Nian, Ruiying Du · IEEE Transactions on Dependable and Secure Computing · 2025
Searchable symmetric encryption (SSE) in the multi-user setting is designed for scenarios where data owners outsource their encrypted data to the cloud while allowing legitimate data users to search on it. However, existing multi-user SSE schemes are not practical in real scenarios with hierarchical user structure such as enterprises and hospitals. Specifically, most schemes require real-time participation of data owners in the authorization or search process, and are not efficient in authorization adjustment, placing a large computational burden on them. In this paper, we focus on hierarchical authorization in the multi-user setting and propose a forward secure scheme, called DSSEHA. In particular, we develop a hierarchical authorization mechanism where the data owner chooses to share her/his data with specific legitimate users who can continue to share with low-level users, thus reducing computational pressure on the data owner. Experiments show that the computation cost of DSSEHA in search is close to the state-of-the-art solution, while the computation cost in update and authorization (e.g., less than 0.1 ms per document for online authorization and less than 0.6 ms for offline authorization) and storage cost (e.g., less than 50.7 MB for Enron subset with 10,000 documents) are much smaller than existing schemes.