Boffins track document 'fingerprints'

Researchers at Imperial College London have found a method of checking a document's authenticity by using the pattern of the paper rather than relying on biometrics or digital signatures. 

The technique uses a low cost scanning laser to view the surface of the document. Microscopic surface imperfections on almost all paper documents, plastic cards and product packaging can be mapped, producing an image as individual as a fingerprint.

Lead author Russell Cowburn, professor of nanotechnology in the Department of Physics at Imperial College London, said: "Our findings open the way to a new and much simpler approach to authentication and tracking.

"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', researchers 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 a thick black marker.

Professor Cowburn and his team are now looking to develop the invention with a spin off company called Ingenia Technology.