Like in 2021 and 2022, I contributed some challenges for Firebird’s internal CTF, which are from the Hong Kong University of Science and Technology. This time I wrote three crypto challenges: Randomsum, Shelter and Threerider.

There were 24 teams participating. There were three solves for Randomsum, while Shelter and Threerider were unsolved during the CTF.

2022 is a life-changer for me. There were some tough decisions and a few surprises.

In the last part, I will include the two non-crypto challenges I wrote for HKCERT CTF 2022: Numbers go brrr and Minecraft geoguessr.

We will continue walking through the remaining crypto challenges I wrote for HKCERT CTF 2022: Mystiz can’t code, Slow keystream and King of Rock, Paper, Scissors.

This is the third year Black Bauhinia co-organized HKCERT CTF. This time I wrote nine challenges: Seven crypto, one reverse and one misc.

Similar to the last year, I have a series of three blog posts walking through the challenges that I wrote. We will discuss the four easier crypto challenges: Flawed ElGamal, Catch-22, Rogue Secret Assistant and Base64 encryption.