The basis of an application to generate and verify QR codes to be printed onto documents.
Could be used when you have a fairly small amount of data that needs to be authenticated.
  Examples: Cashier's Check, Money Order, Driver's License, Event Tickets, etc.
Data is signed and then written into a QR code.
A user can then scan the QR code to verify the data against the signature.
Of course, the public key used for verification would need to come from a trusted source.
I envision a system which looks up the public key using the embedded Org ID from a mediator company (say, paperTrust!).
The application would also have the certificate for paperTrust installed and use that to verify that
  codes obtained are valid.
The system would still be vulnerable to changes to the actual software doing the scanning though.

Run demo.py for an example check generation and verification - written for Linux currently.
  This demo will generate a check using the demo private key.
  You can then print the check.
  If you have a camera you can then scan the video stream for the QR code.
  When the QR code is found it will read out the data and verify the signature against the demo public key.