Cryptology ePrint Archive: Report 2017/1025

Rounded Gaussians -- Fast and Secure Constant-Time Sampling for Lattice-Based Crypto

Andreas Hülsing and Tanja Lange and Kit Smeets

Abstract: This paper suggests to use rounded Gaussians in place of dis- crete Gaussians in rejection-sampling-based lattice signature schemes like BLISS. We show that this distribution can efficiently be sampled from while additionally making it easy to sample in constant time, systematically avoiding recent timing-based side-channel attacks on lattice-based signatures.

We show the effectiveness of the new sampler by applying it to BLISS, prove analogues of the security proofs for BLISS, and present an implementation that runs in constant time. Our implementation needs no precomputed tables and is twice as fast as the variable-time CDT sampler posted by the BLISS authors with precomputed tables.

Category / Keywords: public-key cryptography / Post-quantum cryptography, lattice-based cryptography, sig- natures, Gaussian sampling, BLISS, constant-time implementations.

Date: received 16 Oct 2017

Contact author: c j c smeets at xept nl

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Version: 20171025:025327 (All versions of this report)

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