Rotational Cryptanalysis in the Presence of Constants

Tomer Ashur; Yunwen Liu

Paper 2016/826

Rotational Cryptanalysis in the Presence of Constants

Tomer Ashur and Yunwen Liu

Abstract

Rotational cryptanalysis is a statistical method for attacking ARX constructions. It was previously shown that ARX-C, i.e., ARX with the injection of constants can be used to implement any function. In this paper we investigate how rotational cryptanalysis is affected when constants are injected into the state. We introduce the notion of an RX-difference, generalizing the idea of a rotational difference. We show how RX-differences behave around modular addition, and give a formula to calculate their transition probability. We experimentally verify the for- mula using Speck32/64, and present a 7-round distinguisher based on RX-differences. We then discuss two types of constants: round constants, and constants which are the result of using a fixed key, and provide recommendations to designers for optimal choice of parameters.

Metadata

Available format(s): PDF
Category: Secret-key cryptography
Publication info: Preprint.
Keywords: Rotational cryptanalysis ARX RX-difference
Contact author(s): yunwen liu @ esat kuleuven be
History: 2016-09-19: revised; 2016-08-30: received; See all versions
Short URL: https://ia.cr/2016/826
License: CC BY

BibTeX

@misc{cryptoeprint:2016/826,
      author = {Tomer Ashur and Yunwen Liu},
      title = {Rotational Cryptanalysis in the Presence of Constants},
      howpublished = {Cryptology {ePrint} Archive, Paper 2016/826},
      year = {2016},
      url = {https://eprint.iacr.org/2016/826}
}