Cryptax
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Break my stream Description CrypTopia is testing their next gen encryption algorithm. We believe that the way they implemented it may have a flaw…
We are given a Python file main.py.
Code analysis The flag is encrypted with a key, which is selected randomly:
1 2 flag = b"XXX" key = os.urandom(256) The encryption consists in a XOR with a keystream derived from the key:
1 2 3 4 5 6 7 def encrypt(self, message): result = [] for char in message: key = next(self.
This is a write-up for the following challenges:
Containers Quantum Kraken Device - the Skeleton Key. Calibration 1 and 2. Internet Services Automation 101 (Hackademy track) Sailor Kidz (part with “A” ciphertext) Containers The theme of this CTF was a cruise ship, CVSS Bonsecours (conference and CTF taking place at Marché Bonsecours in Montréal).
Description:
While the Bonsecours is obviously a cruise ship, civilian ships can be chartered to carry cargo in containers.
This challenge consists in a jackpot gain. To get the flag, we need to win and get a balance of 100000 CHF (we’re in Switzerland). The game is available remotely (nc wol.insomnihack.ch 7777) and a local ELF x86-64 binary copy is provided (but without the flag).
I didn’t personally flag this challenge, but worked on it and enjoyed it. Another team mate flagged it :) Then, a few days later, I looked at it more in depth, and found an even quicker way to flag.