Open AccessRotational Cryptanalysis in the Presence of Constants
Author(s) -
Tomer Ashur,
Yunwen Liu
Publication year - 2016
Publication title -
iacr transaction on symmetric cryptology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.715
H-Index - 10
ISSN - 2519-173X
DOI - 10.46586/tosc.v2016.i1.57-70
Subject(s) - cryptanalysis , constant (computer programming) , function (biology) , mathematics , key (lock) , linear cryptanalysis , state (computer science) , algorithm , computer science , cryptography , computer security , evolutionary biology , biology , programming language
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 formula 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.