Add fingerprint impedance to optics for best biometrics spoof detection — researchers
Electrical impedance would seem to be a solid fingerprint biometric method of identity verification, and for the most part, it is. But a team of researchers has found that for the most secure results, it has to be paired with optical scans.
German scientists tested dozens of ways of spoofing fingerprint readers and learned that electrical conductivity — how electricity flows through a material — is almost unbeatable as a measure of authenticity when judging dozens of attack materials.
Making fingerprints, the workhorse of biometrics, more competitive among more complex systems like face and gait biometrics is an ongoing endeavor in the industry, with presentation attack detection (PAD) among the main areas of research.
Their Jenetric capture device acquired a dataset of 757 bona fide presentations and 915 attack presentations from 42 presentation attack instruments, or substances. An algorithm was trained and evaluated on the set.
Forty-one of 42 instruments used to fool scanners programmed to make real-time decisions were detected even if they were unknown to a classifier, according to the researchers. The team included scientists from the Biometrics and Internet Security Research Group and the German Federal Office of Information Security.
Spoofing materials included hot glue, latex, Play-Doh modeling compound, Ecoflex rubber, Gelefix Skin makeup and Silly Putty polymer toy material. (Not tested: grisly cadaver parts.)
The 42nd material was gelatin, which, like skin, is inherently conductive. Optical sensors pick up the difference between skin and gelatin, however, and the researchers recommend devices that combine both techniques.
Optical scanners can be paired with other techniques such as pulse detection and multi-spectral illumination, but impedance can be a more practical option in terms of device footprint, the researchers found.
A flaw in the researchers’ efforts, only brushed in their report, is the growing unease with having to touch something to confirm identities. The industry might move away from systems measuring impedance.