Biometric technologies are still largely undergoing development and are not yet mature enough for widespread use in society. Enrolment is the first and most important stage of any biometric application since the overall efficiency, accuracy and usability of a system depends on this stage. Re-enrolment during the life-cycle of an application is not only necessary because of natural and accidental changes to biometric features, but also to ensure that the acquisition of the sample patterns is performed using state-of-the-art sensor technology. However, not enough large-scale trials exist to help draw conclusions on enrolment procedures. Biometric sample or template storage and their protection are also very important issues. Storing can be done in centralised databases or on portable media such as smart cards. Next follow four technological concerns:
There will always be a compromise between the level of accuracy that can be obtained from a biometric system and the level of performance obtained in operating a live system with a threshold based on operator- or application-defined constraints.
Biometrics could be used in the future to enhance privacy by using a biometric feature to encode a security key, for example a PIN code which allows access to a bank account. There are many advantages to this use of biometrics – primarily that keys thus produced are not linked to the original patterns, are not stored and can be revoked at will.
Technical interoperability and the availability of widely accepted standards and specifications are issues that are currently being researched. They are particularly important in border-control applications, in which different countries are inevitably involved but that will also be the case in the future with worldwide consumer applications (e.g. bank ATMs).
Combining several modalities, e.g. fingerprint and iris, in sequence results in the improvement of a system’s overall efficiency, while combining them in parallel improves a system’s flexibility by providing alternative modes for the verification/identification process. The choice of which modalities to combine is driven by the specific application design. This combination may be performed at different stages of the process, resulting in various benefits. Multimodality could also be viewed as a security enhancement, for example by having the system request alternative modalities to be tested at random in an effort to keep potential impostors at bay.