A High-Security Searchable Encryption Framework for Privacy-Critical Cloud Storage Services

Searchable encryption has received a signi cant attention from the research community with various constructions being proposed, each achieving asymptotically optimal complexity for speci c metrics (e.g., search, update). Despite their elegancy, the recent attacks and deployment e orts have shown that the optimal asymptotic complexity might not always imply practical performance, especially if the application demands a high privacy. Hence, there is a signi cant need for searchable encryption frameworks that capture the recent attacks with actual deployments on cloud infrastructures to assess the practicality under realistic settings. In this article, we introduce a new Dynamic Searchable Symmetric Encryption (DSSE) framework called IncidenceMatrix (IM)-DSSE, which achieves a high level of privacy, e cient search/update, and low client storage with actual deployments on real cloud settings. We harness an incidence matrix along with two hash tables to create an encrypted index, on which both search and update operations can be performed e ectively with minimal information leakage. This simple set of data structures surprisingly o ers a high level of DSSE security while at the same time achieving practical performance. Speci cally, IM-DSSE achieves forward privacy, backward privacy and size-obliviousness properties simultaneously. We also create several DSSE variants, each o ering di erent trade-o s (e.g., security, computation) that are suitable for di erent cloud applications and infrastructures. Our framework was fully-implemented and its performance was rigorously evaluated on a real cloud system (Amazon EC2). Our experimental results con rm that IM-DSSE is highly practical even when deployed on mobile phones with a large outsourced dataset. Finally, we have released our IM-DSSE framework as an open-source library for a wide development and adaptation. Keywords— Privacy-enhancing technologies; private cloud services; dynamic searchable symmetric encryption