Cryptology ePrint Archive: Report 2014/838

SHIELD: Scalable Homomorphic Implementation of Encrypted Data-Classifiers

Alhassan Khedr and Glenn Gulak and Vinod Vaikuntanathan

Abstract: Homomorphic encryption (HE) systems enable computations on encrypted data, without decrypting and without knowledge of the secret key. In this work, we describe an optimized Ring Learning With Errors (RLWE) based implementation of a variant of the HE system recently proposed by Gentry, Sahai and Waters (GSW). Although this system was widely believed to be less efficient than its contemporaries, we demonstrate quite the opposite behavior for a large class of applications.

We first highlight and carefully exploit the algebraic features of the system to achieve significant speedup over the state-of-the-art HE implementation, namely the IBM homomorphic encryption library (HElib). We introduce several optimizations on top of our HE implementation, and use the resulting scheme to construct a homomorphic Bayesian spam filter, secure multiple keyword search, and a homomorphic evaluator for binary decision trees.

Our results show a factor of 10x improvement in performance (under the same security settings and CPU platforms) compared to IBM HElib for these applications. Our system is built to be easily portable to GPUs (unlike IBM HElib) which results in an additional speedup of up to a factor of 103.5x to offer an overall speedup of 1035x.

Category / Keywords: Homomorphic Encryption, FHE, Ring LWE, Bayesian Filter, Email Spam Filter, Spam Filter, Secure Search, Decision Trees, Implementation, GPU.

Original Publication (in the same form): IEEE Transactions on Computers

Date: received 14 Oct 2014, last revised 28 Apr 2016

Contact author: alhassan f khedr at gmail com

Available format(s): PDF | BibTeX Citation

Note: Fixed formatting problems with the \paragragh directive.

Version: 20160428:235300 (All versions of this report)

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