Badge Review: rotc0n Badge by @c0ldbru

I spent some time hanging out with @c0ldbru at Shmoocon, where he had a couple of prototypes of a badge he’s working on for his upcoming convention called rotc0n. I can’t resist a #badgelife oddity so I grabbed one!

The first thing you need to know is that @c0ldbru, along with his business alter ego rot13labs, likes putting together fun activities for his hacker friends. He’s organized groups to ride on the High Roller during defcon. He runs a radio foxhunt where he plants badges with transmitters around a convention and people can try to track them down with radio receivers. I even helped him hide one at Shmoo.

This year @c0ldbru is putting together a hacker convention that he’s calling rotc0n. His vision as he described it to me was it being something like the lobby of Shmoocon - no schedule, no talks, no cost, no badge required for admission. Just a fun, low-key hacker hangout where you can meet new and old friends, share stories, have a few alcoholic (or non-alcoholic) drinks and maybe even get up to some shenanigans.

Wait, did I say there is no badge required? If there’s no badge required, why is there a badge?

Here’s the twist: The date, time and location are a secret! If you wanna know where and when rotc0n is going to be, you need to get one of these badges, and then you have to solve the puzzle. If you solve the puzzle you’ll be rewarded with the details you need to get to the event.

Design and Art

This badge takes the form of a USB-C macro pad. It’s roughly 2” square. Take note: The badge that I have is a pre-production prototype. The production version you get will look a bit different. The obverse (that’s the front) is mostly taken up by the six full-size keyboard keys. The reverse has some artwork and the text ‘rotcon 0 presented by ROT Thirteen Labs’. My prototype has some strings of binary. I am not sure if they mean anything special.

My prototype also some amazing keycaps…they’ve got a ‘Matrix Digital Rain’ motif with yellow text for the letters on the keys. 5 of the keys have very retro-looking function key text on them. The sixth key has a weird eyeball glyph on it. The keyswitches are high quality and clicky.

According to the website, the production version of the badge features a pirate on the reverse. You can’t get the crazy Matrix keycaps that I have, but you can select from one of 7 solid colors. You can also customize the keyswitches with clicky, silent or tactile switches (or let your friend @c0ldbru choose for you).

Hardware

This simple badge takes advantage of an ATmega328p microcontroller. The keyswitches are Kailh Speed Pro heavy switches. Aside from the MCU and the keys, there is not much else hardware-wise. There’s some programming/debug headers, two buttons for interacting with the MCU, and a USB-C port. The badge does not have any “bling” beyond an LED that lights up when it’s plugged in, so it does not need a battery or other power source if you’re wearing it at a con.

Don’t let the simplicity dissuade you, though. It’s a lovely and well-designed device.

It’s only available fully assembled so you need not worry about how difficult it might be.

Software

The whole point of this badge is that you solve the puzzle to learn the date/location of rotc0n, so that’s the main purpose of the software. Plug the USB-C into any computer and see what happens. You should be able to figure out easily how it works…but actually solving the puzzle will probably take some more effort. The puzzle is not a cakewalk but it’s not super difficult either (after all, @c0ldbru WANTS you to come to rotc0n!). It makes great use of the badge’s features.

The badge comes pre-loaded with a QMK compatible bootloader so that you can reprogram it once you’re done with it and use it as a macropad.

Final Thoughts

What a fun idea… both the badge and the rotc0n concept. I had so much fun at Shmoocon just hanging around the hotel bar talking to strangers, that I would love to do it again, especially with Shmoocon closing down after 2025. Hopefully rotc0n can be an annual event.

The badge is high quality, and I had a lot of fun solving the puzzle. It’s a good puzzle. I will not be posting a walkthru of this one, at least not until after rotc0n has ended. When you solve the puzzle, it says you are welcome to share the details with friends and family but you’re asked not to publicly post the info on social media, and I will honor that request. If you have one of the badges and you’re stuck I’d be happy to offer a hint, though.

So, whether you want to go to rotc0n, or you just want one of these cool badges for your collection (only $60 including shipping!) head on over to @c0ldbru’s rot13labs online store and pick one up! While you’re there, check out the other cool gadgets and PCB jewelry that are on offer. You might see something else you like.