In this edition, we will discuss seven characteristics that qualify any human attribute to be considered fit as a biometric item. These seven characteristics are together called the pillars of biometrics
Seven Pillars of biometrics:
Most people wonder what makes a biological characteristic fit for biometric use. For a human measurable quantity (trait) to be considered suitable for use as a biometric item (eg fingerprint or voice print), it must possess seven basic qualities, collectively called the seven pillars of biometrics. We shall review each of these seven qualities and how they determine what qualifies as a biometric quantity, but let us first understand the difference between a biometric trait and a biometric modality.
Biometric triats vs. modality:
We defined biometrics earlier in the first edition as the human physiological or behavioural attributes that distinguish humans and used as a means of verifying or authenticating their identity into information systems. A modality is the human identifier from where these biometric characteristics are extracted, but a trait is that particular physiological or behavioural characteristic that is so extracted from modalities. In most cases the modality is a physiological part of the human body eg the eye or the hand, but can sometimes be a behavioural pattern eg human voice, walking style, signature, etc. This is illustrated in Table 1 below and shows examples of eight of the most commonly-used biometric traits and the corresponding modalities from where they are derived.
Biometric universality stipulates that for any characteristic to be suitable as a biometric item, all humans should possess the characteristic, and the modality should adequately differentiate between any two users. The trait must be universally existent in all individuals as a biological feature or a natural human characteristic, and each potential user must possess it. This explains why a horn is not suitable as a biometric attribute because humans do not grow horns. In other words, a horn is not a universal attribute in humans.
In contrast, traits such as the shape of the palm (palm geometry), blood pattern at the back of the eye (retina pattern), and human voice, all qualify as good biometric traits because of their widespread nature and the commonality of their characteristics from person to person, hence their universality. Every normal human has a hand, an eye, and can talk respectively. These modalities exist in all humans and their characteristic properties vary from one individual to another and hence are very usable as biometric traits and in biometric systems.
2: Uniqueness or Distinctiveness
The uniqueness of a biometric trait refers to its ability to distinguish between different individuals and ensure that each potential user possesses the modality from where it is derived. This quality is a strong factor in evaluating the suitability of a biometric entity, and it specifies that the characteristic of the modality should not appear similar in any two people. For this reason, fingerprints differ from person to person even in identical twins, iris patterns also differ between parents and their children, etc. It is the uniqueness of these traits from person to person that contribute to make them acceptable as biometric quantity.
3: Measurability or collectability
Biometric measurability pertains to the ease of measuring and presenting the trait quantitatively. It is the degree with which the biometric samples can be acquired, analyzed and converted into digital templates for the purpose of identification or verification. Measurability emphasizes that the trait samples should be easy to detect and acquire, eg the ease of scanning to obtain a fingerprint image from a thumb or to retrieve iris patterns from the eye using simple technical instruments and systems such as a thumb scanner or a voice recorder makes these quantities suitable for use as biometric traits.
In practical terms the ease of collecting and assembling trait samples for biometric use is a very important consideration in adopting a given method because certain biometrics by their nature and appearance pose serious difficulties during collection. Eg medical conditions such as throat inflammation can affect speech quality and make high quality voice prints difficult to obtain, injured finger can increase the difficulty of acquiring fingerprints. Similarly scars, marks, tattoos (SMT), or age-induced wrinkles can affect the measurability of facial pattern from the face modality.
Coming up next: We shall discuss the remaining pillars of biometrics including security, permanence, and others.
Talking Biometrics @ ITRealms with Dr. Ken is a weekly online column providing biometric education and associated electronic identity awareness.
About The Columnist
Kenneth Okereafor is an accomplished ICT professional and Cybersecurity expert with over 20 years computing experience in Enterprise ICT innovation management in both private and public sectors. He holds dual PhD degrees in Computer Science (Cybersecurity & Biometrics) and Management (ICT Administration and Governance) with a first class Electronics & Telecommunications Engineering background. He is a United Nations trained Network Security Specialist and is proficient in Network Optimization, Data Protection, Biometric Systems and Digital Forensics. In addition to many published works and conference papers, Kenneth has participated at many international technology events, and has contributed to several national ICT development programmes including the design and development of the National eHealth Strategic Framework 2015 - 2020. He has strong research interests in Digital Innovations, Cloud Security, Cybersecurity Education, Biometric Liveness Detection and Green Computing; and may be reached at nitelken@yahoo.com
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