An Efficiently Searchable Encrypted Data Structure for Range Queries

TL;DR

This paper introduces a new encrypted data structure that enables efficient range queries with provable security against advanced cryptanalysis, supporting fast search times suitable for integration into existing databases.

Contribution

It presents a novel encrypted data structure that is both secure against powerful attacks and supports logarithmic-time searches with linear space, suitable for practical database use.

Findings

Supports logarithmic-time search

Achieves only 10 ms overhead in implementation

Provably secure against chosen plaintext attacks

Abstract

At CCS 2015 Naveed et al. presented first attacks on efficiently searchable encryption, such as deterministic and order-preserving encryption. These plaintext guessing attacks have been further improved in subsequent work, e.g. by Grubbs et al. in 2016. Such cryptanalysis is crucially important to sharpen our understanding of the implications of security models. In this paper we present an efficiently searchable, encrypted data structure that is provably secure against these and even more powerful chosen plaintext attacks. Our data structure supports logarithmic-time search with linear space complexity. The indices of our data structure can be used to search by standard comparisons and hence allow easy retrofitting to existing database management systems. We implemented our scheme and show that its search time overhead is only 10 milliseconds compared to non-secure search.