Independent Badge for DEFCON 25 - MicroPython, Radio, Pairing, Pager Network
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README.md

DEFCON 25 micro:badge

Independent Badge for DEFCON 25 developed on the BBC micro:bit platform. A collaboration of /r/defcon. Runs MicroPython

Usage

  • On startup, displays '/r/defcon' and a skull animation
  • Hold A+B to pair with another micro:badge. Their handle will be saved to pairings.txt
  • Use BTLE and sensors as a pager network: sends handle and topic to paired badges by shaking the badge.
  • Get notified of received pages on the screen. It will flash three times followed by the handle and topic of the page. Hook up speakers/headphones to GND and Pin 0 to hear a page.

Possible Future Dev

  • Increase character support. Handles cannot contain pipes, |, currently
  • Mesh network of micro-badges repeating pages to extend range
  • Encryption of page information to add replay resistance, privacy, authentication, jamming resistance
  • micro:badge on other BTLE platforms
  • Listening post/repeater/logger for analyzing traffic

Pairing

A micro:badge will not respond to a page unless it has been paired. The Two micro:badges can pair by exchanging serial numbers only in pairing mode (A+B). The handle is saved to the file system.

Paging

Simply shake the badge to send a page to all paired handles. This will notify the user visually and, if they have a speaker connected to ground and Pin 0, a short notification tune.

Updating

You will lose all paired handles if you do not back them up before flashing new firmware. This is irreversible, so ensure this has been done before updating.

  1. Copy your paired serial numbers from your micro:bit to your host machine using python tool microfs (ufs on the command line). Paired handles are written to the flat file system of the micro:bit in 'pairings.txt'.
  2. Once backed up you can flash the new badge firmware.
  3. Restore your pairings with ufs put.
  4. Restart your micro:badge to read the restored handles.

Sample that lists files, gets the pairing list, cats it, and then uploads it:

$ ufs ls
pairings.txt
$ ufs get pairings.txt
$
$ cat pairings.txt
TheOtherHandle
RangerDan$
$
$ ufs put pairings.txt