> And then someone prints a billion of those QR codes and drops them in bins. From my original post: [...] as well as provide a unique code for each item so it

> And then someone prints a billion of those QR codes and drops them in bins. From my original post: [...] as well as provide a unique code for each item so it can't be scanned multiple times. > good luck being able to distribute the means of making unique QR codes to every manufacturer under the sun without the method being leaked A registrar could issue one-time non-linear increment codes to manufacturers in bulk lots. The main issue would be a central point of failure, but few people would benefit from a billion 5 cent refund QR codes that can only be registered via a bin using a manual process. Also, codes considered compromised can just be deregistered by the registrar.