In association with heise online

24 July 2007, 18:55

Christiane Rütten

Vein patterns as an alternative to finger prints

The recent launch of a biometric system based on vein pattern recognition by Japanese vendor Hitachi increases competition for common biometric finger print recognition solutions. With its Finger Vein Authentication device, Hitachi enters a niche in the European market, which has been the exclusive domain of Fujitsu, who launched its Palm Secure solution using similar technology, together with a software development kit (SDK), in April 2006.

Hitachi's finger vein detector
Hitachi’s Finger Vein device evaluates the vein pattern of a screened finger. (Picture: Hitachi)
Both vendors already provide their own products based on their vein recognition technology, but mainly focus on the Japanese market. In Europe, Fujitsu concentrates on distributing sensor and SDK, and has third party suppliers produce the final products. At this year’s CeBit fair, Hitachi released its access control system M-1 to the European market.

The underlying principle used to display the vein pattern is the same in both systems. Near-infrared light waves are absorbed particularly well by the blood in the veins, which is low in oxygen. Hitachi’s Finger Vein system uses a light source in the near-infrared range to transmit light through the finger. Veins that intercept this light appear as dark shadows on the sensor picture. PalmSecure by Fujitsu instead transmits near-infrared light onto the palm and then evaluates the light reflected by the tissue. Again, the veins are displayed as a dark pattern of lines. The significant features in the monochrome picture of the network of lines are condensed into a template to be used by the comparison algorithms.

Vein recognition technology has one fundamental advantage over finger print systems: vein patterns in fingers and palms are biometric characteristics that are not left behind unintentionally in every-day activities. In tests conducted by heise, even extreme close-ups of a palm taken with a digital camera, whose RAW format can be filtered systematically to emphasize the near-infrared range, were unable to deliver a clear reproduction of the line pattern. With the transluminance method used by Hitachi it is practically impossible to read out the pattern unnoticed with today's technology. Another side effect of near-infrared imaging also has relevance to security: vein patterns of inanimate bodily parts become useless after a few minutes, due to the increasing de-oxidisation of the tissue.

Fujitsu's palm vein detector
PalmSecure by Fujitsu reads the vein pattern of the palm. (Picture: Fujitsu)
Even if someone manages to obtain a person’s vein pattern, there is no known method for creating a functioning dummy, as is the case for finger prints, where this can be achieved even with home-made tools, as demonstrated by the German computer magazine c't. As in the case with vendors of finger print systems, Hitachi and Fujitsu do not disclose information on liveness detection methods used in their products.

Besides the considerably improved forgery protection, the vendors of vein recognition technology claim further advantages. Compared to finger print sensors, vein recognition systems are said to deliver false rejection rates (FRR) two orders of magnitude below that of finger print systems when operating at a comparable false acceptance rate (FAR). This can be ascribed to the basic structure of vein patterns having a much higher degree of variability than finger prints.

The future will show how well this relatively new technology will perform in practice. According to Hitachi, the idea of using vein patterns as a biometric characteristic was developed in a research paper written at the Japanese Hokkaido University in 1992. Both vendors claim to have huge installations of their systems in successful operation for years, but what is missing so far are relevant independent studies on a very large user base, as well as long-term practical experience, in particular on FRRs and FARs. (mba)

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