archives
Write Up - FCSC 2023
About this
I did some challenges from the France Cybersecurity Challenge of this year, so here just 2 write ups (cuz I may not be really good at explaining how to solve shit). I didn’t solved any tricky chall due to my lack of implication in the CTF, but some of them were pretty fun though, so thanks to the organizers.
I finished 618/1364 on global ranking, and 67/188 on junior ranking.
Write Up - CTF After Dark Winter 2023: Jester
Informations
CTF: CTF After Dark Winter 2023 Author: Jerry
Challenge
Let’s start with some addition: What is 7381 + 8074 ? Oh yeah, I think I forgot to mention. As an extra bonus to make sure you are learning, these numbers change every second :) Tee hee! Good luck keeping up!
(https://jester.acmcyber.com/)
We first encounter a page that ask us to compute an addition on random numbers in less than a second. We’ll obviously code a script that scrap the page, compute the addition, and send back the result in the submit.
Write Up - IrisCTF 2023: babynotrsa | Why you should beware tweaking RSA
Sincere acknowledgements to aaSSfxxx who helped me a bit with mathematical demonstrations and kindly read my write up before I posted it.
This challenge is one of the ones I flagged during the IrisCTF 2023. Thanks to the organizers, I didn’t tried lots challenges but that one was particulary fun as a beginner.
Challenge
Name: babynotrsa Author: sera Description:
Everyone knows RSA, but everyone also knows that RSA is slow. Why not just use a faster operation than exponentiation?