Copy known good serial number + signature.
replycombine with a central authority server network and make it blind signatures and you have untraceable e-cash.
replyBlind signatures don’t work like that. Once you unblind them, they are very traceable. Chaumian e-cash can only be spent once for that reason.
replyNo government wants untraceable e-cash. They want it fully traceable.
replyIt’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.
replyNFC and a challenge-response protocol could work, though, like e.g. the one used in biometric passports.