Google CTF 2022: Maybe Someday
This is the third year I had a writeup on Google CTF (see my writeup in 2020 and 2021). Yet this time it is the official writeup for a challenge - as the challenge author! There are eventually 35 solvers (out of 382 teams) for the challenge.
TSJ CTF 2022 (II): Signature
Breaking 256-bit ECDSA with $k = z \oplus d$ with only six signatures.
Signature is a crypto challenge from TSJ CTF 2022, which ended up having two solves. From this challenge, we can see how ECDSA private keys can be recovered by having a (weak) deterministic ephemeral key, $k$.
TSJ CTF 2022 (I): Cipher Switching Service
@blackb6a played TSJ CTF and CODEGATE CTF this weekend. Both of the CTFs had a bunch of epic (and hard-ish) crypto challenges, which made our head scratched for days.
We were two points behind @balsnctf few minutes before the game ends and I found one more flag. It is proud to tell that we won TSJ CTF 🎉!
Anyway, I will compile writeups for (at least) three challenges for TSJ CTF, namely Cipher Switching Service, Signature and Genie. I will go through Cipher Switching Service as the first part of the series.
MOCSCTF 2022 Postmortem
@blackb6a helped preparing some challenges for MOCSCTF, a 8.5-hour long CTF in Macau. This time I wrote nine challenges and @hoifanrd made one of them (3-AES). This blog post covers the intended solution for all of them.
Intigriti’s XSS Challenge (February 2022)
This is another round of @intigriti’s XSS challenge, and this time it is written by @aszx87410. I spent around four hours solving it.