Pitfalls and Shortcomings for Decompositions and Alignment (Full Version)

Baptiste Lambin; Gregor Leander; Patrick Neumann

Paper 2023/240

Pitfalls and Shortcomings for Decompositions and Alignment (Full Version)

Baptiste Lambin

, Ruhr University Bochum, Bochum, Germany, University of Luxembourg, Esch-sur-Alzette, Luxembourg

Gregor Leander

, Ruhr University Bochum, Bochum, Germany

Patrick Neumann

, Ruhr University Bochum, Bochum, Germany

Abstract

In this paper we, for the first time, study the question under which circumstances decomposing a round function of a Substitution-Permutation Network is possible uniquely. More precisely, we provide necessary and sufficient criteria for the non-linear layer on when a decomposition is unique. Our results in particular imply that, when cryptographically strong S-boxes are used, the decomposition is indeed unique. We then apply our findings to the notion of alignment, pointing out that the previous definition allows for primitives that are both aligned and unaligned simultaneously. As a second result, we present experimental data that shows that alignment might only have limited impact. For this, we compare aligned and unaligned versions of the cipher PRESENT.

Metadata

Available format(s): PDF
Category: Secret-key cryptography
Publication info: A major revision of an IACR publication in EUROCRYPT 2023
Keywords: Supstitution-Permutation Network Alignment PRESENT
Contact author(s): baptiste lambin @ protonmail com
gregor leander @ rub de
patrick neumann @ rub de
History: 2023-02-21: approved; 2023-02-21: received; See all versions
Short URL: https://ia.cr/2023/240
License: CC BY

BibTeX

@misc{cryptoeprint:2023/240,
      author = {Baptiste Lambin and Gregor Leander and Patrick Neumann},
      title = {Pitfalls and Shortcomings for Decompositions and Alignment (Full Version)},
      howpublished = {Cryptology {ePrint} Archive, Paper 2023/240},
      year = {2023},
      url = {https://eprint.iacr.org/2023/240}
}