The "hashing" presents something of a challenge. The input from a scan can be quite a lot of data, a high resolution photograph, a point cloud, a set of RF tim

The "hashing" presents something of a challenge. The input from a scan can be quite a lot of data, a high resolution photograph, a point cloud, a set of RF timings/phases or whatever. The key for future matching must be something small that can be distributed or sent ahead of the delivery, so a hash seems the way to go. But standard hash algorithms are designed for non-collision and sensitivity - any changes of input lead to wildly different outputs. But the physical product has to endure; - handling by humans or machines - mechanical vibration and stress - temperature variations - gravity, natural creep, thermoplasticity - bleaching due to light - variations in the reader, angle, lighting, nearby metal objects That means we need a threshold of fuzziness, where the hash is not broken, until suddenly it is. The more fuzzy we make it the more scope an attacker who knows the method has to craft a deliberate collision to repair tampering effects.