Hack.lu CTF 2021 Crypto Writeup

Because there are not many Crypto listed in the "Stock Market", I decided to join our Webb-expert Web-expert Ozetta for bounty hunting in web, and we got all web challenges done this time. The writeup of the web challenges can be found here....

November 4, 2021 ยท Mystiz

Cyber Apocalypse 2021: Wii Phit & Hyper Metroid

We played Cyber Apocalypse 2021 and I have attempted several crypto challenges. I'll include the challenges Wii Phit and Hyper Metroid in this writeup....

April 25, 2021 ยท hoifanrd

TetCTF 2021: unevaluated

TetCTF is the first CTF I have played in 2021. I recalled from last year that they have cool challenges. This year, there are three crypto challenges. In particular, unevaluated is the hardest among them. Although I did not solve them, I dug into rabbit holes and had a lot of struggle, uh, fun. Challenge Summary There is a 128-bit prime $p$. Define $\cdot: \mathbb{Z}_{p^2}^2\times\mathbb{Z}_{p^2}^2\rightarrow\mathbb{Z}_{p^2}^2$ by \[(x_1, y_1)\cdot(x_2, y_2) := \left(\left(x_1x_2-y_1y_2\right)\ \text{mod}\ p^2, \left(x_1y_2+y_1x_2\right)\ \text{mod}\ p^2\right),\]...

January 3, 2021 ยท Mystiz

hxp CTF 2020: Hyper

I was teamed up to play hxp CTF as @blackb6a last week. The hxp team had come up with a collection of hard challenges. In particular, there are two series of crypto challenges with a total of five parts. I will be writing on the hyper challenge and some follow-up and unanswered questions regarding to hyperelliptic curves. โ“˜ ๐—ข๐—ณ๐—ณ๐—ถ๐—ฐ๐—ถ๐—ฎ๐—น ๐˜€๐—ผ๐˜‚๐—ฟ๐—ฐ๐—ฒ๐˜€ ๐˜€๐˜๐—ฎ๐˜๐—ฒ๐—ฑ ๐˜๐—ต๐—ฎ๐˜ ๐˜๐—ต๐—ถ๐˜€ ๐—ถ๐˜€ ๐—บ๐—ถ๐˜€๐—น๐—ฒ๐—ฎ๐—ฑ๐—ถ๐—ป๐—ด Seriously. I knew nothing on hyperelliptic curves prior to the CTF....

December 20, 2020 ยท Mystiz

Dragon CTF 2020 Writeup

Dragon CTF 2020 is definitely had my best CTF moments. There are big brain moments and I have been mind-blown for multiple times during the game. This time we have teamed up with @blackb6a. I have solved all the crypto challenges and two challenges with my teammates. There are three challenges writeup in this post: Bit Flip (parts 2 and 3) Frying in motion babykok Bit Flip (Crypto, 155+324+343 points) Solved by Mystiz....

November 23, 2020 ยท Mystiz, GeoffreyY

Google CTF 2020: Oracle

I was teamed-up with @blackb6a on Google CTF this time. I have solved 7 challenges alone and 3 challenges with my teammates. In particular, Oracle is a crypto challenge with 13 solves. It has got me spending 12 hours. All in all, it was a great experience in terms of learning, but my liver hurts. This piece of writeup may be very computation intensive, just because I would like to make everything clear....

August 25, 2020 ยท Mystiz