Cryptology ePrint Archive: Report 2017/1021

Bricklayer Attack: A Side-Channel Analysis on the ChaCha Quarter Round

Alexandre Adomnicai and Jacques J.A. Fournier and Laurent Masson

Abstract: ChaCha is a family of stream ciphers that are very efficient on constrainted platforms. In this paper, we present electromagnetic side-channel analyses for two different software implementations of ChaCha20 on a 32-bit architecture: one compiled and another one directly written in assembly. On the device under test, practical experiments show that they have different levels of resistance to side-channel attacks. For the most leakage-resilient implementation, an analysis of the whole quarter round is required. To overcome this complication, we introduce an optimized attack based on a divide-and-conquer strategy named bricklayer attack.

Category / Keywords: implementation /

Original Publication (with minor differences): INDOCRYPT 2017

Date: received 14 Oct 2017

Contact author: a adomnicai at trusted-objects com

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Version: 20171025:025049 (All versions of this report)

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