The development of biometric systems depends on the purposes of the identification or verification, which are in themselves different activities. The following figure presents how biometric systems work. Identification or recognition aims at determining who subject is without information given by the individual. Identification
143
Boulgouris, Nikolaos V., et. al.,Biometrics, Theory, Methods, and Applications, above n 7, p. 69.
144
Bolle, Ruud M., et. al.,Guide to Biometrics, above n 7, p. 4.
145
Zhang, David D., Automated Biometrics Technologies and Systems, above n 7, p. 10.
146 Idem; Hopkins, Richard, “An introduction to biometrics and large scale civilian identification”,
above n 7; Boulgouris, Nikolaos V., et. al., Biometrics, Theory, Methods, and Applications,above n 7.
147
For further details, see Appendix C. How Biometric Systems Work
148
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and recognition mean that characteristics are selected from a database to produce a list of possible or likely matches149. Meanwhile, authentication or verification as the name suggests seeks to verify the individual based on information provided by the user. Authentication and verification mean that when a person makes a claim that he or she is a specific person, only that specific person’s characteristics are checked to see if they match150.
Figure 4. Purposes of Biometric Systems
In an identification system, a huge database is used to store hundreds of thousands of people’s digital biometric features, whereas in a verification system, it is not necessary to have a database since the objective of such a system is to verify a person’s identity, which means the registered pattern is displayed when a comparison is conducted151. More detailed information on how biometric systems work, is included in Appendix C.
2.8.1. Accuracy and limits of biometric systems. Most behavioural biometric systems are still in the testing stage, but most of physical characteristics are operational. The accuracy and effectiveness of these systems need to be checked in a real time operation environment. An essential legal concern for biometric systems is related to the level of accuracy of data.
149
Boulgouris, Nikolaos V., et. al., Biometrics, Theory, Methods, and Applications, above n 7, p. 47.
150
Idem.
151
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The biometric systems have used two performance measurements to rank the level of matching accuracy152, known as the false rejection rate and the false acceptance rate. The first is concerned with the number of instances an authorized individual is falsely rejected by the system while the second refers to the number of instances a non-authorized individual is falsely accepted by the system153.
For Zhang, a biometric system’s accuracy is determined by combining the rates of false acceptance and false rejection. The performance of a biometric system, and therefore the false rejection rate and false acceptance rate, could be affected by154:
Environmental conditions like extreme temperature and humidity
The age, gender, ethnic background and occupation of the user
The beliefs, desires and intentions of the user. If a user does not wish to interact with the system, then performance will be affected.
The physical make-up of the user. A user without any limbs cannot use signature biometrics.
Hopkins claims that “[i]t needs to take into account different mechanisms for interpretation of data and different environmental conditions when the data is captured”155
. Hopkins explains that biometric systems can present two kinds of errors or mistakes: false acceptance –when the biometric system authenticates an impostor- and false rejection –when the system rejects a valid user156
.
Fingerprints and iris recognition biometric systems are ideal for limiting entry into secured areas to known and trusted individuals. But, this biometric system is not very useful for recognizing people in public places whereas biometric facial recognition systems can recognize people at a distance, without their knowledge or
152
Bolle, Ruud M, et. al., Guide to Biometrics, above n 7, p. 8.
153
Idem.
154
Zhang, David D., Automated Biometrics Technologies and Systems, above n 7, p. 11.
155 Hopkins, Richard, “An introduction to biometrics and large scale civilian identification”,
above n 7.
156
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cooperation157. More recently in the United Kingdom, as a result of threats to public safety, some public places have been heavily populated with video surveillance cameras. On average, a person moving through London is captured on video over five times a day158. Fingerprint systems can be used either for identification or authentication. Iris recognition is more suited for use as personal verification than fingerprints159.
In biometric voice identification systems, there is no prior identity claim, and the system decides who the person is, or what group the person belongs to. While biometric voice authentication systems analyse an utterance from an unknown speaker and compare it with the model of the speaker whose identity is claimed. The fundamental difference between identification and authentication is the number of decision alternatives160.