Cryptology ePrint Archive: Report 2014/816

FHEW: Bootstrapping Homomorphic Encryption in less than a second

Léo Ducas and Daniele Micciancio

Abstract: The main bottleneck affecting the efficiency of all known fully homomorphic encryption (FHE) schemes is Gentry’s bootstrapping procedure, which is required to refresh noisy ciphertexts and keep computing on encrypted data. Bootstrapping in the latest implementation of FHE, the HElib library of Halevi and Shoup (Crypto 2014), requires about six minutes per batch. We present a new method to homomorphically compute simple bit operations, and refresh (bootstrap) the resulting output, which runs on a personal computer in just about half a second. We present a detailed technical analysis of the scheme (based on the worst-case hardness of standard lattice problems) and report on the performance of our prototype implementation.

Category / Keywords: public-key cryptography / FHE, bootstrapping, Ring-LWE

Date: received 8 Oct 2014, last revised 2 Mar 2015

Contact author: lducas at eng ucsd edu

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Version: 20150302:165340 (All versions of this report)

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