Laser surface authentication - reading Nature's own security code

A laser-based security technique called Laser Surface Authentication (LSA) is described in which diffuse laser scattering is used as a probe of the naturally-occurring randomness present in virtually all surfaces. LSA brings the principles of biometric identification currently used in human fingerprint- or iris-recognition to the world of inanimate objects such as paper documents, plastic cards, high value branded products and a range of other things that are commonly counterfeited or smuggled.