Removing the Field Size Loss from Duc et al.'s Conjectured Bound for Masked Encodings

Julien Béguinot; Wei Cheng; Sylvain Guilley; Yi Liu; Loïc Masure; Olivier Rioul; François-Xavier Standaert

Paper 2022/1738

Removing the Field Size Loss from Duc et al.'s Conjectured Bound for Masked Encodings

Julien Béguinot, LTCI, Télécom Paris, Institut Polytechnique de Paris, Palaiseau, France

Wei Cheng

, LTCI, Télécom Paris, Institut Polytechnique de Paris, Palaiseau, France

Sylvain Guilley

, Secure-IC, LTCI, Télécom Paris, Institut Polytechnique de Paris, Palaiseau, France

Yi Liu, LTCI, Télécom Paris, Institut Polytechnique de Paris, Palaiseau, France

Loïc Masure

, ICTEAM Institute, Université catholique de Louvain, Louvain-la-Neuve, Belgium

Olivier Rioul

, LTCI, Télécom Paris, Institut Polytechnique de Paris, Palaiseau, France

François-Xavier Standaert

, ICTEAM Institute, Université catholique de Louvain, Louvain-la-Neuve, Belgium

Abstract

At Eurocrypt 2015, Duc et al. conjectured that the success rate of a side-channel attack targeting an intermediate computation encoded in a linear secret-sharing, a.k.a masking with shares, could be inferred by measuring the mutual information between the leakage and each share separately. This way, security bounds can be derived without having to mount the complete attack. So far, the best proven bounds for masked encodings were nearly tight with the conjecture, up to a constant factor overhead equal to the field size, which may still give loose security guarantees compared to actual attacks. In this paper, we improve upon the state-of-the-art bounds by removing the field size loss, in the cases of Boolean masking and arithmetic masking modulo a power of two. As an example, when masking in the AES field, our new bound outperforms the former ones by a factor . Moreover, we provide theoretical hints that similar results could hold for masking in other fields as well.

Note: Adding acknowledgements => final version for COSADE.

Metadata

Available format(s): PDF
Category: Implementation
Publication info: Published elsewhere. COSADE 2023
Keywords: masking security bound Mrs. Gerber's Lemma
Contact author(s): julien beguinot @ telecom-paris fr
wei cheng @ telecom-paris fr
sylvain guilley @ secure-ic com
yi liu @ telecom-paris fr
loic masure @ uclouvain be
olivier rioul @ telecom-paris fr
francois-xavier standaert @ uclouvain be
History: 2023-02-11: last of 3 revisions; 2022-12-18: received; See all versions
Short URL: https://ia.cr/2022/1738
License: CC BY

BibTeX

@misc{cryptoeprint:2022/1738,
      author = {Julien Béguinot and Wei Cheng and Sylvain Guilley and Yi Liu and Loïc Masure and Olivier Rioul and François-Xavier Standaert},
      title = {Removing the Field Size Loss from Duc et al.'s Conjectured Bound for Masked Encodings},
      howpublished = {Cryptology {ePrint} Archive, Paper 2022/1738},
      year = {2022},
      url = {https://eprint.iacr.org/2022/1738}
}