Hands-On: The Pandemic DEF CON Badge Is An Audio Cassette

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 online 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?

28 thoughts on “Hands-On: The Pandemic DEF CON Badge Is An Audio Cassette

          1. And I always thought my best is the bestest best there is ;(

            This reminds me of a poster I saw at my university that showed a collection of bad Powerpoint slides. One read something along the lines of “Finding the best optimal solution”…

    1. I didn’t notice that but I’m a bit confused by
      “… has moved offline in response to the global pandemic, and the virtual event spins up August 6-9”
      shouldn’t that be “moved online”?

      I mean DEF CON is online every year but this time it’s online-only isn’t?

      Btw.: How do you participate a virtual event offline? ;-)

  1. It would be fun to really analyze the actual tape itself. From the article, there’s music on it, but obviously it’s what could would be hidden that’s fun to think about.

    I know you can shift/adjust a typical playback head to line up with the stereo tracks. Is it possible to hide data between these stereo tracks? If it’s a stereo recording, I’d like to invert the L/R tracks against each other and see what comes out from the difference.

    Also, what if you completely flip the ribbon inside out, and play the bottom side? Would they have gone as far as to have a custom double sided tape made? I’d guess not, as it would be too expensive.

    I’m guessing most of the data is hidden within the normal tracks, but just in creative ways.

  2. 1) sounds we can not hear (encoded data)
    2) waveforms that sound the same but look different (on a scope, fft, ect) (encoded data)
    3) mis-alignment of tape heads revealing a bonus one and a half tracks (encoded data?)
    4) like someone else said; L-R differencees (fake stereo) (encoded data)
    5) the number station may be timing hints, frequncy hints, azmuth offsets, or even waveshape samples -indicating PPT/MFM/PFM/ect
    6) the lanyard looks runic, looks like “phrases” created by combining several letters (used in symbolic form) to create complete ideas, seeing as runnic has so few symbols but combined that can tell a story, a story thats a substitute for a symbol/word, followed by yet another phrase made from yet more symbols/words. or its not runic but the very waveforms you need to look for on the tape?!?!?!?

    6) all 6 above possibilities combined

    ie digitize SideA-Left and SideA-Right then adj tape-head azmuth until you get a waveform (that we can not hear) and record SideA-Middle, do difference until irregular waveform patterns appear. convert those waveforms using some mathematical model, possibly suggested by the numbers part, then resulting waveforms can be slowed-down and injected into a device with an ancient form of modem protocol (PRE-handshaking such as BELL-101 BELL-102 BELL-202 ect)

    now re-do it all from scratch so it can be done real-time, all powered with batteries.

    at least thats what i would have done if i set it all up, check out the “normal” songs, (coded) irregularities may show up there too, or just lyrycs chosen to hint at “3rd option”=”3rd track”, and “differing all day”=”difference recording” “slow it down baby”=”slow it down and examine small variations (ultrasonic frequencies)”

    the lanyard goes through the tape transport (or capstand holes?) and loops around itself, but that ones probably not part of the puzzle.

    goodday people of earth, and dont forget to donate to a nearby charity!

  3. Ummmm $50 for a cassette tape? :) Nice but prohibitively expensive (especially here in EU). I get that the event is free now and I suppose this is to recoup some of the sunk costs. But still, a lot.

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