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1/1/2008
Since our last look at biometrics, some things have changed, but alas, some have not; hand cream can still thwart the best of readers.
DARN. LOCKED OUT AGAIN. All too often
that was my experience when experimenting
with a fingerprint-based security system back
in 1999. About one time in five I would have to
disable the fingerprint scanner to be able to
log on to my desktop computer. But biometric
identification devices have been getting better
and cheaper. The question is: Are they
ready for prime time?
About Biometric Identification
Biometric identification schemes fall into two general categories: physiological and behavioral. Physiological schemes are related to the physical characteristics of our body and include fingerprints, iris and retinal scans, as well as hand and facial characteristics. Behavioral schemes include keystroke dynamics, signature, and voice. ("Biometrics Go Mainstream," in the April 2006 issue of Campus Technology, provides an introductory description of the various biometric identification systems in use.) Yet, how does a biometric system work in practice?
First, a sensor acquires digital information about a biometric parameter-for example, the shape of your hand. Then, information from the sensor is processed and features extracted-for instance, the size of your fingers and hand. Finally, data about the features are used to construct a template, which is the synthesis of all the characteristics that could be extracted from the source. Authentication is done by comparing a newly generated template with the one on file.
How Well Do Biometrics Work?
The performance of a biometric system is measured using two parameters: the false acceptance rate (FAR), which is the probability that the system will incorrectly accept an invalid user; and the false rejection rate (FRR), which is the probability that a valid user will be rejected. Since the FAR and FRR are inversely related, the point at which the two values are equal, the EER, or equal error rate, is frequently cited as a measure of the overall performance of the system.
The National Institute of Standards and Technology conducts regular tests of commercially available biometric identification systems. Because of homeland security considerations, the testing focuses on fingerprints, face recognition, and iris scans. As would be expected, iris scans have the best overall performance. However, because of their relatively high cost and inconvenience to users, they have seen little adoption in higher education. Some of the NIST results for fingerprint and face recognition systems are shown below.
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