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.