The surfaces of most paper documents, plastic cards and cardboard packages contain unique “fingerprints” that could be used to combat fraud, according to physicists.

The fingerprint is contained in microscopic imperfections on the surface and can be read by a portable laser scanner. The results could eventually eliminate the need for expensive security measures — such as holograms, chips and special inks — on passports, identity cards and pharmaceutical packaging.

University of Sheffield physicists used a phenomenon called “laser speckle” to examine the structure of different surfaces, using photodetectors to record the intensity of the light reflected from four different angles. They then quantified how much random fluctuations on the paper differed from the mean value (called the zero positional shift) and converted these values into 1s and 0s to obtain the unique fingerprint code.

The probability of two pieces of paper sharing the same fingerprint is less than 1 in 10²⁷ and for smoother surfaces, such as plastic cards and cardboard, it is 1 in 10²⁰.