Observations on the SIMON block cipher family

Stefan Kölbl; Gregor Leander; Tyge Tiessen

Paper 2015/145

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.

Metadata

Available format(s): PDF
Publication info: A minor revision of an IACR publication in CRYPTO 2015
Keywords: SIMON block cipher differential cryptanalysis linear cryptanalysis boolean functions
Contact author(s): stek @ dtu dk
History: 2015-07-03: last of 2 revisions; 2015-02-27: received; See all versions
Short URL: https://ia.cr/2015/145
License: 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},
      url = {https://eprint.iacr.org/2015/145}
}