Lilya Budaghyan - University of Bergen, Norway

Lilya Budaghyan is a professor and the head of the Selmer Center in Secure Communication, Department of Informatics, University of Bergen, Norway. She received her Ph.D. degree from the University of Magdeburg, Germany, in 2005, and the habilitation degree from the University of Paris 8, France, in 2013. Her main research interests include cryptographic Boolean functions and discrete structures and their applications. She also conducted her research at Yerevan State University (Armenia), the University of Trento (Italy) and Telecom ParisTech (France). She was a recipient of the Trond Mohn Foundation Award in 2016, the Young Research Talent Grant from the Norwegian Research Council in 2014, a Postdoctoral Fellowship Award from the Foundation of Mathematical Sciences of Paris in 2012, and the Emil Artin Junior Prize in Mathematics in 2011. Since 2018, she has been a member of the Norwegian Academy of Technological Sciences (NTVA).

Talk title: In search of equivalence relations for cryptographic Boolean functions

Talk abstract: Boolean functions are among the most fundamental objects in pure and applied mathematics and computer science. In particular, in cryptography block ciphers are designed by appropriate composition of Boolean functions, and the security of a block cipher depends on special Boolean functions called S-boxes. The two main cryptographic properties of S-boxes, differential uniformity and nonlinearity, measure the resistance of S-boxes to the two most powerful classical attacks, differential and linear cryptanalyses, respectively. Equivalence relations preserving differential uniformity and nonlinearity divide the set of all functions into classes. Among such equivalence relations are affine, extended affine and CCZ-equivalences. Studying these equivalence relations and finding new ones is important for the following two reasons: first, they can be powerful construction methods providing for each function a huge class of functions with the same properties, and, second, instead of checking invariant properties for all functions, it is enough to check only one in each class. In the present talk we discuss known equivalence relations of cryptographic functions and possible ways for finding new such equivalence relations.

Matthieu Rivain - Cryptoexperts, France

Matthieu is a researcher and entrepreneur in cryptography. He has conducted his PhD study at the University of Luxembourg between 2006 and 2009 while being a cryptography engineer at Oberthur (now Idemia). In 2010, Matthieu joined CryptoExperts, a young technology and service company in cryptography, which he today leads as CEO. Matthieu’s research interests cover several aspects of applied cryptography such as secure cryptographic implementations, side-channel attacks, elliptic-curve cryptography, white-box cryptography, and more recently zero-knowledge proofs. Matthieu has been an active member of IACR since 2007, and in particular of the CHES conference, which he co-organised in 2015 (as general co-chair) and in 2018 (as program co-chair).

Talk Title : TBA