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Transaction Processing on Confidential Data using Cipherbase

Abstract

Cipherbase is a comprehensive database system that provides strong end-to-end data confidentiality through encryption. Cipherbase is based on a novel architecture that combines an industrial strength database engine (SQL Server) with lightweight processing over encrypted data that is performed in secure hardware. The overall architecture provides significant benefits over the state-of-the-art in terms of security, performance, and functionality.

This paper presents a prototype of Cipherbase that uses FPGAs to provide secure processing and describes the system engineering details implemented to achieve competitive performance for transactional workloads. This includes hardware-software codesign issues (e.g. how to best offer parallelism), optimizations to hide the latency between the secure hardware and the main system, and techniques to cope with space inefficiencies. All these optimizations were carefully designed not to affect end-to-end data confidentiality. Our experiments with the TPC-C benchmark show that in the worst case when all data are strongly encrypted, Cipherbase achieves 40% of the throughput of plaintext SQL Server. In more realistic cases, if only critical data such as customer names are encrypted, the Cipherbase throughput is more than 90% of plaintext SQL Server.

Design Philosophy

A large part of database processing does not deal with data value semantics. This includes moving data, query setup/result communication, and almost all of concurrency control and recovery. Almost all of this processing is unaffected whether we are handling plaintext or encrypted data. Cipherbase exploits this observation and uses a regular database system (SQL Server) to implement this functionality.

At the same time, a core part of database processing does depend on data value semantics, including query expression evaluation over tuples and comparisons during index traversals. In general, these operations cannot be performed directly over encrypted data. In Cipherbase, we factor out such processing and run it in a trusted module (TM). The trusted module is designed to be inaccessible to the adversary, allowing us to securely decrypt data and perform operations on plaintext.

References

[1] Arvind Arasu, Ken Eguro, Manas Joglekar, Raghav Kaushik, Donald Kossmann, Ravi Ramamurthy, Transaction Processing on Confidential Data using Cipherbase, IEEE International Conference on Data Engineering 2015 (ICDE 2015).