## Cryptology ePrint Archive: Report 2015/534

Problems, solutions and experience of the first international student's Olympiad in cryptography

Sergey Agievich and Anastasiya Gorodilova and Nikolay Kolomeec and Svetla Nikova and Bart Preneel and Vincent Rijmen and George Shushuev and Natalia Tokareva and Valeria Vitkup

Abstract: A detailed overview of the problems, solutions and experience of the first international student's Olympiad in cryptography, NSUCRYPTO'2014, is given. We start with rules of participation and description of rounds. All 15 problems of the Olympiad and their solutions are considered in detail. There are discussed solutions of the mathematical problems related to cipher constructing such as studying of differential characteristics of S-boxes, S-box masking, determining of relations between cyclic rotation and additions modulo $2$ and $2^n$, constructing of special linear subspaces in $\mathbb{F}_2^n$; problems about the number of solutions of the equation $F(x)+F(x+a)=b$ over the finite field $\mathbb{F}_{2^n}$ and APN functions. Some unsolved problems in symmetric cryptography are also considered.

Category / Keywords: secret-key cryptography / cryptography, block ciphers, boolean functions, AES, Olympiad, NSUCRYPTO

Original Publication (in the same form): Prikl. Diskr. Mat. (Applied Discrete Mathematics), 2015, to appear.