HKCERT CTF 2022 Postmortem (III): The Remaining Challenges

HKCERT CTF 2022 Postmortem (III): The Remaining Challenges
In the last part, I will include the two non-crypto challenges I wrote for HKCERT CTF 2022: Numbers go brrr and Minecraft geoguessr.
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HKCERT CTF 2022 Postmortem (II): Harder Crypto Challenges

HKCERT CTF 2022 Postmortem (II): Harder Crypto Challenges
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.
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HKCERT CTF 2022 Postmortem (I): Easier Crypto Challenges

HKCERT CTF 2022 Postmortem (I): Easier Crypto Challenges

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.

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HKCERT CTF 2021 Postmortem (IV): The Remaining Ones

HKCERT CTF 2021 Postmortem (IV): The Remaining Ones
We will cover the remaining challenges I wrote in this part: Flag Checker™, The Wilderness and Potion of Ciphermath.
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HKCERT CTF 2021 Postmortem (III): The Reverse Challenges

HKCERT CTF 2021 Postmortem (III): The Reverse Challenges
As the third part of the series, three reversing challenges will be included: The Hardest Path, A Junior Mathematician and Let’s Chill.
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HKCERT CTF 2021 Postmortem (II): Harder Crypto Challenges

HKCERT CTF 2021 Postmortem (II): Harder Crypto Challenges
In this part, three harder crypto challenges will be covered: Tenet: The Plagarism, Sratslla SEA and Sign in Please, Again.
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HKCERT CTF 2021 Postmortem (I): Easier Crypto Challenges

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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HKCERT CTF 2020 Postmortem

HKCERT CTF 2020 Postmortem
On August 2020, @blackb6a was invited to co-organize HKCERT CTF 2020 (which is held on November 2020) as one of the challenge authors. This is a CTF for secondary and tertiary students in Hong Kong. Although I had experience preparing CTFs earlier, this is actually the first CTF officially prepared by Black Bauhinia. I have written four challenges for this CTF - Sanity Check II (Web), LF2 (Reverse), Sign In Please (Crypto) and Calm Down (Crypto). There will also be some stories behind the scenes.
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