Two German hackers say they have developed a technique to defeat biometric fingerprint scanners used to authenticate electronic purchasing systems. Unlike an earlier fingerprint attack developed by the pair last year, this system creates latex fingertip patches designed to be used while under observation.

The hackers, known as Starbug and Lisa, presented their attack at the Chaos Computer Camp, an open-air event which took place last weekend in East Berlin. "We have developed methods to fake fingerprints on the run," said Lisa.

The past technique used graphite powder and adhesive tape to lift fingerprints off surfaces and fool scanners into accepting them as genuine. This new method involves taking a digital picture of the fingerprint image produced by the graphite powder and adhesive tape. This image is enhanced with graphical software, printed on to foil, and transfered to a photosensitive printed circuit board. The board is exposed and etched to create the three dimensional structure of the fingerprint. It is then transferred to liquid latex which is dried to create a thin material similar to the consistency of a latex glove. This small piece of latex is attached to a person's fingertip prior to using the scanner.

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