HKCERT CTF 2021 Postmortem (I): Easier Crypto Challenges
Black Bauhinia coorganized HKCERT CTF 2021 and helped 95% of the technical stuffs, including challenge setting, platform development, infrastructure and etc. I will be writing a series of blog posts talking about the contest, and the first four would be the writeups of the challenges those I wrote. In the first blog post, we will be going through four easier crypto challenges: A Joke Cipher, Cipher Mode Picker, Key Backup Service 1 and Key Backup Service 2.
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BSides Ahmedabad CTF 2021 Writeup
No, we did not win. I see that coming and took a screenshot during the game. BSides Ahmedabad CTF 2021 is organized by @zer0pts. That implies that players could spend a day happily working on the challenges. I enjoyed working on the challenges a lot. I'll go through the harder crypto challenges and the reversing challenge called Collapsed License in this blog post.
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pbctf 2021: Seed Me & Yet Another RSA
I am playing as a part of @blackb6a this time for perfect blue's annual pbctf. This time there are six crypto challenges and I first blooded 🩸 half of them. I solved five of them, and collaborated with @TWY (who made 99% of the process) for Seed Me. In this blog post, I will cover Seed Me and Yet Another RSA. I tried to make the whole post beginner friendly, hence included more details than necessary. I was originally going to discuss all of the crypto challenges, but I found it is too demanding and tiring.
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Google CTF 2021 Quals Writeup
This is me playing another Google CTF with @blackb6a, ending up on the 25th place. I aced the crypto challenges and solved some challenges with my teammates. I have a strong feeling that Black Bauhinia grown a lot between the two Google CTFs and I am often backed by my teammates this time. Anyway, I will be covering all of the crypto challenges in this blog post.
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PlaidCTF 2021: Leaky Block Cipher
PlaidCTF this year had very insane challenges. Although I have spent a lot of time working on those crypto challenges, I was only able to solve leaky block cipher. This completely legitimate™ block cipher looks a bit like GCM, but my computer plumber keeps complaining about water residue. Can you help me spot the leak? The challenge has a hand-crafted AEAD scheme. We are required to go through 20 rounds of challenges, and this is how each round proceeds...
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