This work focuses on deterministic and non-deterministic nonlinear approximations of block ciphers (or of permutations). We show that nonlinear invariants correspond to deterministic nonlinear approximations (i.e., with correlation ±1) and often capture a strong linear hull effect. Also, we point out that, by transforming the cipher under consideration by conjugating each transformation with a fixed permutation, we are able to transfer many methods from linear cryptanalysis to the nonlinear case. Using this framework we show that some appropriate transformed versions can be used for capturing a strong linear hull effect in a simple manner. (joint work with Christof Beierle and Gregor Leander)
Anne Canteaut received a Ph.D. degree (1996) and an “Habilitation à Diriger des Recherches” (2006) in computer science from University Pierre-et-Marie Curie (Paris, France). Since 1997, she has been a research scientist with Inria. She is currently senior research scientist and the scientific head of the SECRET research team at Inria Paris. Her research interests include symmetric cryptography and coding theory. In particular, she is the co-designer of several cryptographic primitives, including the stream ciphers Sosemanuk, Decim and Kreyvium, the hash function Shabal and the block cipher Prince. She has served on program committees for more than 60 international conferences such as Eurocrypt, Crypto, Asiacrypt and FSE. Most notably, she served as program chair for Indocrypt 2004 (Chennai, India), for WCC 2011 and WCC 2019 (Workshop on Coding and Cryptography), for FSE 2012 (Fast Software Encryption, Washington DC, USA) and for Eurocrypt 2020 (Zagreb, Croatia). She currently serves on, or has served on the Editorial Boards of the following journals: IEEE Transactions on Information Theory (2005-2008, and since 2018), Finite Fields and their Applications (since 2013) and Applicable Algebra in Engineering, Communication and Computing (since 2016). Since 2017, she is the head of science of the Inria Paris research center.