The Seventh International Olympiad in Cryptography NSUCRYPTO: problems and solutions. - Anastasiya Gorodilova; Natalia N. Tokareva; Sergey Agievich; Claude Carlet; Valeria Idrisova; Konstantin Kalgin; D. Kolegov; Alexandr Kutsenko; Nicky Mouha; Marina Pudovkina; Aleksei Udovenko (CoRR, 2021)