BlackAlps 2026 CTF
I participated in the BlackAlps 2026 CTF , a jeopardy-style competition that required physical presence at La Marive in Yverdon-les-Bains . The challenges were independent tasks across topics such as cryptography, web security, forensics, and hardware; each solution yielded a flag to submit for points. This year, prizes went to good presentations of solutions rather than to the teams with the most solves. I had little experience with AI tools and wanted to see how far I could get using Codex as my solver. Before the event, I wrote one instruction asking it to download every challenge, sort them by likely difficulty, and start solving. I began with Codex Plus (CHF 20) . About 20 minutes into the CTF, only 33% remained of its five-hour allowance , so I upgraded to Pro 100 (CHF 83) , something I had already intended to do independently of the competition. After the CTF, including the work on this write-up, 82% of my weekly usage remained ; I had not used any of my remaining resets. I st...