In short, the task is to provide vectors flipping specific bits in an encryption scheme resembling [ring learning with errors](https://en.wikipedia.org/wiki/Ring_learning_with_errors).
See the [original wripetup](https://upbhack.de/posts/2021/12/writeup-beyond-the-mountain-crypto-from-backdoorctf-2021/).

Original writeup (https://upbhack.de/posts/2021/12/writeup-beyond-the-mountain-crypto-from-backdoorctf-2021/).