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Cryptax

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Broken OTP (NOPS CTF 2024)

Description This challenge has a very short description: “i heard OTP it the most secure encryption algorithm ever” and supplied a Python source file. Because that code only worked on Python 3.12, a Dockerfile was also supplied. De-obfuscating the source code The source code is intentionally obfuscated. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 import random secret = 'XXXXXXXXXXXXXXXXXXXX' PINK = 118 RED = 101 YELLOW = 97 GREEN = 108 BLACK = __builtins__ PURPLE = dir e = getattr(BLACK, bytes([RED, PINK, YELLOW, GREEN]).

Joe Dohn (NOPS CTF 2024)

Description This challenge from the Misc category was saying: “Is it me or there is a strange guy on the discord server ?” Solution Joining the Server I went on the Discord server of the CTF, and found a guy named “Joe Dohn”. I sent him a message, and immediately he replied by inviting me to a private Discord server. Actually, Joe is not real person but a bot. This private server has 2 channels: a general channel, and one dedicated to conversation with me.

Just Read and JoJo is Missing (NOPS CTF 2024)

Those 2 challenges had already been flagged by a team mate when I started working on the CTF. But, during the CTF, at a time when I was getting frustrated not to flag other challenges, I decided to do them again on my own lol. Both challenges are very beginner friendly. Just Read Description This challenge is in the Reverse category, with a simple description “Find a way to break this” and an executable main is provided.