National Cyber League

With the next season’s competition coming up, I wanted to document my participation in the NCL Fall 2025 Team Game. I offhandedly mentioned forming an NCL team with a few friends back in October, and that quickly turned into purdon’t.

Team purdon’t left to right:
Colin Saumure, Kevin Archer, Tommaso Graewe, Casey Gukasova, Haiyan Xuan, David Racovan, and Nikolai Viswanath

For added context, the National Cyber League competition is a semi-annual cybersecurity competition comprised of both an individual game and a team game. Competitors are tasked with solving challenges from a wide range of categories, including cryptography, reverse engineering, network traffic analysis, open source intelligence, and more.

Fifth Place Trophy - Experienced Bracket

Personal Contributions

My efforts during the competition were primarily focused on the Cryptography and Network Traffic Analysis categories. I found the networking challenges somewhat underwhelming in difficulty, though poor wording on one particular question cost us a decent chunk of accuracy.

There was a cryptography challenge (hard) that I found particularly memorable, in which alphabetic characters had been substituted by three-digit numbers. The catch was that a letter could be assigned more than one numeric value.

The provided hint for this challenge was that it was a communication sequence between two users. This helped me deduce that the first word of each line was the username followed by a colon. I used this information to infer other words and perform translation by hand. After like 45 minutes, I was able to decode the entire message. Despite the tedious nature of the task, it felt incredibly validating to have solved a custom encryption scheme by hand.