Australasian Science: Australia's authority on science since 1938

Fooling Fingerprint Scanners Foiled

By Magdeline Lum

Magdeline Lum reports on quirky experiments and research findings.

The full text of this article can be purchased from Informit.

Secret agents around the world have been dealt a blow in defeating fingerprint scanners. The days of cutting the finger off from their adversaries or fresh corpses to get into buildings, drive away in fancy cars or logging into a computer are over.

These may sound like scenes straight out of a spy movie, but in March 2005 an owner of a Mercedes S class equipped with a fingerprint protection system found himself the target of thieves. He was first kidnapped when the thieves stole his car to bypass the fingerprint-based security. The thieves decided soon after to cut off his finger before letting him go.

But Clarissa Hengfoss and her colleagues at Dermalog Identification Systems in Hamburg, Germany, have now developed an easy way for fingerprint scanners to tell the difference between a living finger and a severed digit. It is based on how living tissue changes colour, or “blanches”, when blood is squeezed out from capillaries. You can see this for yourself by pressing one of your fingertips to see the pink colour turn white. This difference can be measured.

Living fingers absorb LED light at 550 nm on the first contact with a surface and then at 1450 nm at full contact with a sensor when the skin is blanched. The fingers from three cadavers did not show any change in light absorbance. It is hoped that this will result in a fingerprint scanner that is not...

The full text of this article can be purchased from Informit.