Comment by piratejon

10 hours ago

That's really neat! Seems potentially adaptable to paper currency--a verifiable QR code digital signature of the bill's serial number creates a cryptographically hard obstacle to counterfeiting!

It’s a bunch of static signed data, which is hard to modify but trivial to copy. Not exactly what you’d want for bank notes.

NFC and a challenge-response protocol could work, though, like e.g. the one used in biometric passports.