Capture the Flag 🚩

Capture the flag (CTF) is a competition where contestants earn points by finding secret messages ("flags") hidden in radio signals. Challenge yourself and improve your GNU Radio skills!

The GRCon 2023 CTF took place from September 5-8, 2023. Even though the competition has ended, you can still register and play online, however the scoreboard will remain frozen to reflect the scores at the end of the official competition period. A small number of challenges were only playable on-site in Tempe during the competition period. These are indicated with [on-site] but remain in the challenge list to preserve a record of the competition.

To get started:

1. Read over the rules.
2. Join the GRCon23 Capture the Flag Matrix channel.
3. Register an account and log in.

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Source code & writeups [Spoiler alert!]

Some challenge designers have published the source code of their challenges, and some players have posted writeups of their solutions. Email ctf@gnuradio.org if you'd like to have your writeup added to the list.

• Live walk-through session, recorded September 9, 2023
• DVB-S2 GRCon23 CTF challenge by Daniel Estévez
• Source code for "DVB-S2" by Daniel Estévez
• GRCon 2023 CTF Challenge (NRSC5) by Vlad Fomitchev
• Source code for "Not Really Superior Clatter V" by Vlad Fomitchev
• Source code for "Signal identification", "Demod 101", "Fox hunting", "Go for the Gold", and "Broken modulator" by Clayton Smith
• Noir CTF Challenges by Aerospace Team Platypus
• Source code for "Noir" by Aerospace Team Platypus
• Source code for "Numbers Mixup" and "Digital and Voice" by Jeff Long

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Want more CTF?

Check out some of the past competitions, which are still playable:

• GRCon 2022 CTF
• GRCon 2020 CTF ("deviations")