This repository contains the source code of the magnetic_tape challenge from NullCon Berlin HackIM CTF 2025.
It is a crypto challenge, which I estimated to be of easy-medium difficulty. In the end it was solved by 37 teams. With a dynamic system for assigning points (the more teams solving the challenge the fewer points it's worth) it was worth 392 points in the end, the maximum was 500.
If you want to play the challenge, check out the challenge folder. If you want to my exploit and my "official" write-up, check out the solution folder. You can also check other write-ups on https://ctftime.org/task/31257 .