SQL on Structurally-Encrypted Databases

We show how to encrypt a relational database in such a way that it can efficiently support alarge class of SQL queries. Our construction is based solely on structured encryption (STE) anddoes not make use of any property-preserving encryption (PPE) schemes such as deterministicand order-preserving encryption. As such, our approach leaks considerably less than PPE-basedsolutions which have recently been shown to reveal a lot of information in certain settings (Naveedet al., CCS ’15 ). Our construction is efficient and—under some conditions on the database andqueries—can have asymptotically-optimal query complexity. We also show how to extend oursolution to be dynamic while maintaining the scheme’s optimal query complexity. ∗[email protected]. Work done in part at Microsoft Research.†tarik [email protected]. Work done in part at Microsoft Research, IMT Atlantique and Colorado State.