https://pnasis.gitlab.io/tags/modular-arithmetic/ Recent content in Modular Arithmetic on pnasis Hugo en-us Mon, 29 Jun 2026 11:16:35 +0300 https://pnasis.gitlab.io/posts/sekaictf-2026-cryptography-writeup-oneline6ryp7o/ Mon, 29 Jun 2026 11:16:35 +0300 https://pnasis.gitlab.io/posts/sekaictf-2026-cryptography-writeup-oneline6ryp7o/ <h2 id="introduction">Introduction</h2> <p>    A few days ago, I participated in <a href="https://ctftime.org/event/3113">SekaiCTF 2026</a>, a <strong>Jeopardy-style</strong> CTF competition, together with my teammate under <a href="https://ctftime.org/team/431287">Echelon Obscura</a>. Despite competing as a team of only two players, we finished <strong>178th out of 926</strong> teams, a result we were particularly happy with considering both the difficulty of the event and the level of competition.</p> <p>    During the competition, I primarily focused on the <em><strong>Cryptography</strong></em>, <em><strong>Reverse Engineering</strong></em> and <em><strong>Blockchain</strong></em> categories. The event featured a wide variety of well-designed challenges ranging from elegant mathematical puzzles to implementation vulnerabilities and interesting reverse engineering problems. Several of these challenges stood out not only because they required solid technical knowledge but also because they rewarded careful observation and a methodical approach rather than brute force.</p>