‘Unhackable’ Danish anti-counterfeiting system is built on sand

In 2013, 1,500 high-fashion counterfeit leather handbags with a potential street value of $14m were seized in Los Angeles (Credit: Jaime Ruiz/US Customs and Border Protection)

The optical authentication system uses sand doped with three rare earth lanthanides, each of which glows under a different wavelength of light. Separate buckets of sand are doped with europium, terbium and dysprosium, with the three buckets then mixed together in a single vessel.

A piece of ‘tape’ is dipped in the vessel to create a unique pattern with thousands of grains of sand, but which measures just a few millimetres wide. This fingerprint can then be embedded in leather or glass or milled into metal.

When a manufacturer attaches the marking to an item, the imprint is photographed at different wavelengths. The resulting patterns of illuminated europium, terbium and dysprosium are then combined in a single image which is digitally stored in the manufacturer’s database. Using a proprietary reader and software, the digital key can then be used to authenticate the physical key. According to the researchers, the encoding capacity of the system is 6 × 10¹⁰⁴, making it virtually impossible to successfully counterfeit. The work is described in Science Advances.