Cryptology ePrint Archive: Report 2016/1023

Constant-Time Higher-Order Boolean-to-Arithmetic Masking

Michael Hutter and Michael Tunstall

Abstract: Converting a Boolean mask to an arithmetic mask, and vice versa, is often required in implementing side-channel resistant instances of cryptographic algorithms that mix Boolean and arithmetic operations. In this paper, we describe a method for converting a Boolean mask to an arithmetic mask that runs in constant time for a fixed order. We propose explicit algorithms for a second-order secure Boolean-to-arithmetic mask conversion that uses 31 instructions and for a third-order secure mask conversion that uses 56 instructions. We show that our solution is more efficient than previously proposed methods for any choice of masking-scheme order, typically by several orders of magnitude.

Category / Keywords: implementation / Side-channel analysis

Date: received 27 Oct 2016, last revised 22 Dec 2016

Contact author: michael tunstall at cryptography com

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Version: 20161222:183711 (All versions of this report)

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