25 Sep 2019
In this challenge, we need to recover a message that is encrypted through 4 different RSA keys, while knowing some of the bits of the private keys. In particular, we are given code that generates 4 different RSA keys (of ~2100 bits each), permutes them, encrypts the flag by each of them in succession, and then provides us the encrypted flag. Additionally, we are given the moduli of the keys, as well as the lower...
02 Jan 2019
In this challenge, we had to obtain remote code execution, simply by
exploiting a 1-day bug that forgot the difference between -0 and
+0. This has probably been one of the most difficult, fun, and
frustrating bugs I have ever exploited.
24 Oct 2018
Last weekend was HITCON CTF 2018, and it was really awesome! I
personally spent time on various super interesting challenges. Below
is just one of them that I happened to solve on the first day. I found
to be particularly interesting to solve since I never have had a
chance to dive into any homomorphic encryption systems before.
31 Dec 2016
This was a great challenge, and I learnt a lot, even though I ended up
spending many hours (over 10 hours!) on it.