A Blackbox Challenge


Using your wits and creativity, can you figure out how a device works just from observing how it reacts to your input?

Connected to this server is a hardware device which you can interact with over the internet (go ahead, 6138443103). This is a digital cash device, which was used to hold and transact payments. It uses a "smart chip" to store money in up to 12 accounts. Recently a local municipality decided to deprecate these devices, and they can now be obtained on ebay.
We are going to reverse engineer these devices. Whether you are a veteran hardware hacker, or just starting and want to learn, there are challenges here for you to dig into.

I also have one (just one) of these that still works, AND the matching system that can accept money from it. If someone succeeds in learning about how to reconfigure these devices, I can provide query responses from this device. The ultimate challenge is to learn how the devices work, and prove that knowledge by converting one of the "common" devices to replicate the "rare" device and have the digital money work on this real system.

Good luck!

Goal posts

Some math, some hardware, some creativity, some logical deduction -- start where-ever you want. Roughly the main starting options are given in the navigation tabs above: Math, Hardware, testing inputs/outputs.

Some goals in rough order of difficulty or dependency:

  1. Make hardware to communicate with device for testing (can skip this and use the supplied interface for testing)
  2. Figure out high level command structure
  3. Subtract money from device
  4. Change device ID
  5. Add money to device
  6. Change device "region" (the initial data device gives after power on)
  7. Set device "region"
  8. Figure out authentication algorithm well enough to determine configuration needed for duplicating "rare" device
  9. Full victory -- combine everything to duplicate "rare" device and demonstrate money transfer on working system