Who says only humans should have fingerprints? A technique for generating artificial ones could see banknotes, jewellery and other valuables tagged with a unique pattern to fight counterfeiters.
Wook Park of Kyung Hee University in Seoul, South Korea, and his colleagues created fake fingerprints by mixing two kinds of plastic to make discs that were 0.4 millimetres across. They then coated the discs with a thin layer of silica and dried them out. The mismatch between the plastic core, which shrank when dried, and the outer silica, which held firm, made the discs wrinkle like deflated balloons and resemble fingerprints.
But just looking like fingerprints didn’t guarantee they would be as individual as the real thing. To test their uniqueness, the team created thousands of patterned discs and analysed them using standard fingerprint recognition algorithms. The minutiae – the ridges used to identify fingerprints – on the fakes were similar to human prints. In fact, the fakes had more variety, because human fingerprints are likely to orient themselves to our fingertips.
The team also experimented with prints shaped like letters, squares and stars to add variety. Theoretically, their method can produce 10135 unique patterns – far more than the number of atoms in the universe. Researchers disagree on exactly how many unique human prints there are, but the number is likely to be much lower, in the billions.
“Since it has far more unique patterns than human fingerprints, we can use it for large numbers of products as an authentic ID,” says Park. Anyone attempting to forge the fingerprint by generating their own would end up with a completely different pattern, revealing the tagged item to be an impostor.
To test this out, they applied fake fingerprints to a passport, a ring and a watch. The prints are just large enough to be visible to the human eye, but small enough to be unobtrusive. Using a portable microscope attached to an iPhone camera, they took a picture of the fingerprints and could see the ridges. The resolution was too low to uniquely identify them, but the team is currently developing image-enhancing techniques to do this in the future.
Arun Ross of Michigan State University in East Lansing says these fake fingerprints might someday replace your own, if they can be securely linked to an individual. Right now, if your fingerprints are stolen there is no way to revoke them, like you would a compromised password. “There could be some value in considering this for creating cancellable biometrics,” he says.
Journal reference: Advanced Materials, DOI: 10.1002/adma.201405483
Source: New Scientist