DEF CON 14 badge
This year the DEF CON badge is electronic. Designed by Joe Grand, it features two blinking blue LEDs (almost bright enough to see the printer tracking dots; maybe we just need to drive the badge with a higher voltage). The badge seems to contain a secret message; since I'm missing Joe Grand's talk to write this blog post, I can't go ask him for hints.
The badge has five modes, controlled by a tiny momentary switch on the back. The modes are off, both LEDs on steady, both LEDs blink together, both LEDs alternate, and what I call the data mode.
In the data mode, the LEDs appear to flash a long preprogrammed message, over 100 bits in length, using a data representation that I'm still not sure of. I managed to find a repeating feature that I could recognize by sight (four flashes on the right LED, followed by both on followed by right LED on followed by both on followed by left on followed by right on followed by both on). The baud rate is something over 2 (I should measure it more carefully), and hence the bit rate is over 4. The pattern repeats with a period of 58 seconds. It's possible that it was meant to be one minute and that the clock rate was affected by problems with the supply voltage or the tolerance of some component.
Actually, that means that there are over 232 bits in the message. I imagine that 256 bits is a likely number.
I'd like to digitize the data coming out of the badge without having to have a person transcribe it by hand. Possibly I could find some kind of photodiode that I can get in a circuit near TTL levels for a parallel port.
