Biometrics Identification - Advice-07

Biometrics - The Way Forward?

A wide range of biometric authentication methods are now available. Many of these have captured the imagination of potential users - but are they the panacea they appear?

Biometrics have great intuitive appeal as they promise absolute identification for high risk applications. Without doubt the newer technologies are very sophisticated and many are viewed as very sexy, yet many enthusiasts overlook some fundamental limitations and assume that biometrics can, and perhaps will, supersede conventional key / identification technologies.

What are biometrics?

Biometrics comprise a number of technologies that rely on measuring a physical characteristic of some part of someone`s body in order to positively identify that person. Commercial examples of the technology include: fingerprint, voice, iris, retina, hand shape and facial geometry.

In all cases, biometric authentication involves scanning the chosen part of the body, reducing the scan to a set of numerical values, and comparing the result with a previously registered reference set or "template". The trick is to pick out certain characteristic markers (often known as loci) that can be algorithmically distilled down each time to the same set of values - more or less - within a very large space of possible values. Thus the set should for practical purposes be unique.

The template has to be stored somewhere so that it can be recalled each time a user presents themselves. Central server storage is economical but requires careful design of the link with the remote user system and encryption of the template, to prevent eavesdropping and subsequent replay attack, whilst some of the new technologies rely on storing a copy of the template locally within the verification device itself.

How useful are biometrics?

Inaccuracies are inevitable in biometric measurement. The conditions under which scanning takes place change from place to place, and time to time. "Noise" in the process, changes in the body part either through disease or simply ageing will change the raw data entering the distillation process. To make sure that a more or less consistent set of values results each time, any biometric algorithm has to discard much of the raw data, which obviously leads to a chance (hopefully relatively small) that two  different people can generate the same biometric measurement.

In high risk environments, the chances of two persons generating the same measurement can be made very small. The price paid for such accuracy is however a risk that a valid user could be rejected (false negative error). Although somewhat gruesome in concept, in certain military applications for instance, fingerprint identification is also linked to blood pulse and body temperature to ensure that a severed finger with the correct fingerprint will not match the stored template, etc.

There is a balance therefore between foolproof accuracy and what is deemed to be politically or socially acceptable or commercially viable. Whilst an individual may feel comfortable about offering a finger to a fingerprint reader, many may feel much less comfortable about offering an eye up for retina scanning, etc.

Whilst a level of (false negative) rejection may be acceptable for a high level military application where absolute identification is essential, it may be more difficult to explain to a homeowner why his or her house will not let them in through the front door at 4 o`clock in the morning when its raining just because their body part scan does not match!

Without doubt as biometrics evolve, the technology will take its place alongside many types of more conventional; access control systems, locking technologies, identification mechanisms, etc. As with most technological innovations however there is likely to be a not insignificant gestation and proving period before take-up becomes socially and commercially acceptable and its operational use more widespread.

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