An overview of the Eight International Olympiad in Cryptography "Non-Stop University CRYPTO"; ; et al E-print/Working paper (2022) Non-Stop University CRYPTO is the International Olympiad in Cryptography that was held for the eight time in 2021. Hundreds of university and school students, professionals from 33 countries worked on ... [more ▼] Non-Stop University CRYPTO is the International Olympiad in Cryptography that was held for the eight time in 2021. Hundreds of university and school students, professionals from 33 countries worked on mathematical problems in cryptography during a week. The aim of the Olympiad is to attract attention to curious and even open scientific problems of modern cryptography. In this paper, problems and their solutions of the Olympiad’2021 are presented. We consider 19 problems of varying difficulty and topics: ciphers, online machines, passwords, binary strings, permutations, quantum circuits, historical ciphers, elliptic curves, masking, implementation on a chip, etc. We discuss several open problems on quantum error correction, finding special permutations and s-Boolean sharing of a function, obtaining new bounds on the distance to affine vectorial functions. [less ▲] Detailed reference viewed: 94 (0 UL) A Complete Study of Two Classes of Boolean Functions: Direct Sums of Monomials and Threshold Functions; Meaux, Pierrick ![]() in IEEE Transactions on Information Theory (2022), 68(5), 3404--3425 In this paper, we make a comprehensive study of two classes of Boolean functions whose interest originally comes from hybrid symmetric-FHE encryption (with stream ciphers like FiLIP), but which also ... [more ▼] In this paper, we make a comprehensive study of two classes of Boolean functions whose interest originally comes from hybrid symmetric-FHE encryption (with stream ciphers like FiLIP), but which also present much interest for general stream ciphers. The functions in these two classes are cheap and easy to implement, and they allow the resistance to all classical attacks and to their guess and determine variants as well. We determine exactly all the main cryptographic parameters (algebraic degree, resiliency order, nonlinearity, algebraic immunity) for all functions in these two classes, and we give close bounds for the others (fast algebraic immunity, the dimension of the space of annihilators of minimal degree). This is the first time that this is done for all functions in large classes of cryptographic interest. [less ▲] Detailed reference viewed: 114 (2 UL) The Seventh International Olympiad in Cryptography NSUCRYPTO: problems and solutions; ; et al E-print/Working paper (2021) Detailed reference viewed: 176 (0 UL) On the Sixth International Olympiad in Cryptography NSUCRYPTO; ; et al E-print/Working paper (2020) Detailed reference viewed: 176 (0 UL) |
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