This paper presents an expanded discussion of the mathematical curriculum within the Cybersecurity specialization at the Faculty of Military Technology, University of Defence, with particular emphasis on discrete mathematics and number theory. Building on earlier work describing experiences in teaching Mathematics I–III and Graph Theory, we focus on selected number-theoretic topics and their concrete applications in cybersecurity- and cryptography-oriented courses. Through representative examples solved by students in discrete mathematics courses, we illustrate how concepts such as modular arithmetic, finite fields, and algebraic structures support the understanding of cryptographic algorithms and protocols. The paper further reflects on the role of mathematically grounded education in preparing future cybersecurity specialists for national defence tasks in the context of contemporary geopolitical challenges.