Surface imperfections yield unique ‘fingerprints’

LONDON, ENGLAND - A unique “fingerprint” formed by microscopic surface imperfections on almost all paper documents, plastic cards and product packaging could be used as a cheaper method to combat fraud. This inherent identity code is virtually impossible to modify and can be easily read using a low-cost portable laser scanner, according to research carried out at Imperial College London and Durham University and published in the latest issue of Nature (28 July 2005, Vol 436).

All non-reflective surfaces have naturally occurring roughness that is a source of physical randomness. This could provide in-built security for a range of objects such as passports, ID and credit cards, and pharmaceutical packaging, replacing more costly measures such as holograms or security inks.

“Our findings open the way to a new and much simpler approach to authentication and tracking,” said lead author Russell Cowburn, professor of Nanotechnology in the Department of Physics, Imperial College London. “This is a system so secure that not even the inventors would be able to crack it since there is no known manufacturing process for copying surface imperfections at the necessary level of precision.”

Using the optical phenomenon of laser speckle, Cowburn and his colleagues examined the fine structure of different surfaces using a focused laser, and recorded the intensity of the reflection. The technique was tried on a variety of materials including matt-finish plastic cards, identity cards and coated paperboard packaging and resulted in clear recognition between the samples. This continued even after they were subjected to rough handling including submersion in water, scorching, scrubbing with an abrasive cleaning pad, and being scribbled on with thick black marker.

Cowburn and his colleagues are now working with a spin-out company, Ingenia Technology, to take this product to market.