Capture the Flag / OTA 2015

This past weekend I participated in my first Capture the Flag challenge which was hosted by Matt Hamilton (Eriner) and other folks of the OTA Team. It was an epic 72 hours. We teamed up with my brother and took 5th place.

During those 72 hours I learned a lot more than I knew about steganography, cryptography, filesystem superblocks, and even got to sharpen my math skills. I must admit I knew nothing (or maybe forgot everything) about calculus.

My favorite challenge was cracking an Enigma-encoded message. It turns out that the military version of this 1920s machine has over 158 quintillion (!) different ways to setup the initial key. My first blind attempt at bruteforcing it yielded only one million combinations in about 10 minutes. Yeah, good luck with that.

The Enigma Machine

Luckily there are much more effective algorithms to crack the message in fewer steps (yes, faster than the Turing Bombe), by relying on quadgram statistics, given that we know the language of the original message.

Thanks to the OTA Team for hosting this online event! If you’re looking to join such an event in the future, check out

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