Equi-Joins Over Encrypted Data for Series of Queries

TL;DR

This paper introduces a new encryption scheme enabling efficient and secure equi-joins over encrypted data, minimizing data leakage and supporting series of queries in cloud database systems.

Contribution

It presents a novel encryption scheme that improves security and efficiency for equi-joins over encrypted data, with provable security guarantees.

Findings

Reduces leakage to equality of matching rows

Reveals only the transitive closure of query leakages

Demonstrates efficiency over TPC-H dataset

Abstract

Encryption provides a method to protect data outsourced to a DBMS provider, e.g., in the cloud. However, performing database operations over encrypted data requires specialized encryption schemes that carefully balance security and performance. In this paper, we present a new encryption scheme that can efficiently perform equi-joins over encrypted data with better security than the state-of-the-art. In particular, our encryption scheme reduces the leakage to equality of rows that match a selection criterion and only reveals the transitive closure of the sum of the leakages of each query in a series of queries. Our encryption scheme is provable secure. We implemented our encryption scheme and evaluated it over a dataset from the TPC-H benchmark.