My DEF CON Safe Mode badge just arrived in the mail this afternoon. The Vegas-based conference which normally hosts around 30,000 attendees every year has moved offline in response to the global pandemic, and the virtual event spins up August 6-9. Known for creative badges, North America’s most well-known infosec con has a tick-tock cycle that alternates electronic and non-electronic badges from year to year. During this off-year, the badge is an obscure deprecated media: the audio cassette.

This choice harkens back to the DEF CON 23 badge which was an vinyl record — I have the same problem I did back in 2015… I lack access to playback this archaic medium. Luckily [Grifter] pointed everyone to a dump of the audio contents over at Internet Archive, although knowing how competitive the badge hacking for DEF CON is, I’m skeptical about the reliability of these files. Your best bet is to pull the dust cover off your ’88 Camry and let your own cassette roll in the tape deck. I also wonder if there are different versions of the tape.

But enough speculation, let’s look at what physically comes with the DEF CON 28 badge.


The cassette tape itself is the real deal, delivered in a jewel case and shrink-wrapped with plastic. Made of purple-tinted clear plastic, each side features a masked logo and the number 28 silk-screened on along with side letters A and B. On the B-side is a quote from Ghost in the Shell:

I feel confined, only free to expand myself within boundaries.
Motoko Kusanagi

It’s somewhat surprising to see something so straight-forward printed here. I’d expect bizarre characters that are part of a larger puzzle. Perhaps this sets the tone for the the mysteries within, and weird markings are by no means missing form the package.

The part of the lanyard which goes around the back of your neck is packed with strange characters. It was a bit difficult to photograph but hopefully these images are enough to get you started with the puzzle. The liner notes that come folded into the cradle of the jewel case provide a track list and a thank you from [The Dark Tangent], which is then followed by cryptic messages from [1o57], DEF CON’s long-time puzzle master.


The audio on the tape is surely the best part of the badge hacking challenge. Side A starts off with a set of tones waiting to be decoded, the B side sounds like a number station at the start. Don’t be fooled, there’s great music included on the bulk of the recording and it’s worth a listen even if you’re not involved in the con.

Have you already been analyzing the audio? We’d love to hear more about it in the comments below. And I’ve started a project over on Hackaday.io for anyone who wants to work collaboratively on unlocking the secrets of the DC28 badge. Anyone can pop into the public chat on that project, and those actively working on the challenge can click the “Join this project’s team” in the left sidebar of that project page to get write access that lets you add projects logs and images.

One thing that makes this feel 100% like a DEF CON badge… how the heck are we supposed to hook the lanyard to the badge to wear the thing around?

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