### Observations on the SIMON block cipher family

Stefan Kölbl, Gregor Leander, and Tyge Tiessen

##### Abstract

In this paper we analyse the general class of functions underly- ing the Simon block cipher. In particular, we derive efficiently computable and easily implementable expressions for the exact differential and linear behaviour of Simon-like round functions. Following up on this, we use those expressions for a computer aided approach based on SAT/SMT solvers to find both optimal differential and linear characteristics for Simon. Furthermore, we are able to find all characteristics contributing to the probability of a differential for Simon32 and give better estimates for the probability for other variants. Finally, we investigate a large set of Simon variants using different rotation constants with respect to their resistance against differential and linear cryptanalysis. Interestingly, the default parameters seem to be not always optimal.

Note: Updated to the revised version of CRYPTO and supplementary tutorial.

Available format(s)
Publication info
A minor revision of an IACR publication in CRYPTO 2015
Keywords
SIMONblock cipherdifferential cryptanalysislinear cryptanalysisboolean functions
Contact author(s)
stek @ dtu dk
History
2015-07-03: last of 2 revisions
See all versions
Short URL
https://ia.cr/2015/145

CC BY

BibTeX

@misc{cryptoeprint:2015/145,
author = {Stefan Kölbl and Gregor Leander and Tyge Tiessen},
title = {Observations on the SIMON block cipher family},
howpublished = {Cryptology ePrint Archive, Paper 2015/145},
year = {2015},
note = {\url{https://eprint.iacr.org/2015/145}},
url = {https://eprint.iacr.org/2015/145}
}

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