Comment »Posted on Thursday 26 March 2009 at 3:08 pm by Jacob Aron
In Biology, Getting It Wrong, Inventions & Technology

A new type of biometric identification may soon be joining fingerprint and retina scanners, in the form of X-ray photographs of a person’s knees, according to Lior Shamir of the National Institutes of Health and Salim Rahimi, a computer engineer at State University of New York.

Their report, to be published in the International Journal of Biometrics, suggests that an individual’s knees differ enough from any others to make them of use in identification. Using an algorithm known as wnd-charm, which is normally used to diagnose medical knee joint issues, the authors suggest that knee X-rays are a viable alternative to external biometrics.

Whilst it is possible to fool existing biometrics with fake fingerprints and contact lenses, the pair say it would be much harder for any would-be impersonators to spoof another’s knees. It seems that knees also stay consistent, with X-rays taken several years earlier still suitable for verification purposes.

The new technique doesn’t quite measure up to existing technology, with accuracy results lower than retina or fingerprint identification, though the researchers say refining the wnd-charm algorithm could improve this.

I say don’t bother. I think biometrics are a terrible, terrible idea. They can’t be replaced if someone succeeds in spoofing your identity, as it would be difficult to legally acquire a new set of knees. There is also the issue of those who cannot use their eyes, fingerprints or indeed knees to identify themselves, because they don’t have them. In a society where knee-ID becomes the norm, how could such people function?

Finally, X-raying people’s knees repeatedly to authenticate them sounds like a really bad idea. Multiple exposures to X-rays is incredibly dangerous, which is why your dentist will hide behind a protective screen when scanning your teeth.

The average person will be exposed to relatively small doses of X-rays during their life, so there is no need to worry about routine medical procedures. Biometric techniques however must be used all the time if they are to be of any use, and scanning knees in this way would undoubtedly cause health issues. The authors suggest terahertz imaging in the place of X-rays could offer more precise data, and it would also solve the problem of repeated exposure. I wonder though, do we really want to be asked “Can I see your knees, please?” at every security checkpoint? No thanks.


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