Frank Almond, whose Stradivarius was stolen at Taser-point, and a close up of a Taser firing, showing the ejecting of tiny, "anti-felon ID" tags.Jennifer Brindley, left; Axon, right When fired, Tasers ...

A cryptographic tag uses terahertz waves to authenticate items by recognizing the unique pattern of microscopic metal particles that are mixed into the glue that sticks the tag to the item's surface.