### On the Success Rate of Side-Channel Attacks on Masked Implementations: Information-Theoretical Bounds and Their Practical Usage

##### Abstract

This study derives information-theoretical bounds of the success rate (SR) of side-channel attacks on masked implementations. We first develop a communication channel model representing side-channel attacks on masked implementations. We then derive two SR bounds based on the conditional probability distribution and mutual information of shares. The basic idea is to evaluate the upper-bound of the mutual information between the non-masked secret value and the side-channel trace by the conditional probability distribution of shares given its leakage, with a help of the Walsh–Hadamard transform. With the derived theorems, we also prove the security of masking schemes: the SR decreases exponentially with an increase in the number of masking shares, under a much more relaxed condition than the previous proof. To validate and utilize our theorems in practice, we propose a deep-learning-based profiling method for approximating the conditional probability distribution of shares to estimate the SR bound and the number of traces required for attacking a given device. We experimentally confirm that our bounds are much stronger than the conventional bounds on masked implementations, which validates the relevance of our theorems to practice.

Available format(s)
Category
Secret-key cryptography
Publication info
Published elsewhere. ACMCCS 2022
DOI
10.1145/3548606.3560579
Keywords
masking power EM analysis side-channel attack
Contact author(s)
akira ito as @ hco ntt co jp
rei ueno a8 @ tohoku ac jp
naofumi homma c8 @ tohoku ac jp
History
2022-09-07: last of 2 revisions
See all versions
Short URL
https://ia.cr/2022/576

CC BY

BibTeX

@misc{cryptoeprint:2022/576,
author = {Akira Ito and Rei Ueno and Naofumi Homma},
title = {On the Success Rate of Side-Channel Attacks on Masked Implementations: Information-Theoretical Bounds and Their Practical Usage},
howpublished = {Cryptology ePrint Archive, Paper 2022/576},
year = {2022},
doi = {10.1145/3548606.3560579},
note = {\url{https://eprint.iacr.org/2022/576}},
url = {https://eprint.iacr.org/2022/576}
}

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