Also referred to as Biometric Identification, Biometrics is a method used to identify human beings using one or more of their traits or characteristics. In computer science, Biometrics is used for access control and as an identification method.

Biometric identifiers are defined as measurable and distinctive characteristics that are used for describing and labelling individuals. Biometric identifiers have two categories:

These are the characteristics which relate to a human’s body. Some examples of physiological characteristics include (which are however, not limited to):

• DNA.
• Face Recognition.
• Fingerprint.
• Hand Geometry.
• Iris Recognition.
• Palm Print.
• Retina.
• Scent/odor.

These are the characteristics which relate to a human’s behavior. Some examples of behavioral characteristics include (but not limited to):

• Gait.
• Typing Rhythm.
• Voice.

There is a group of researchers who prefer to use a different name for the behavioral characteristics. The name they coined for describing behavioral characteristics of Biometric identifiers is Behaviometrics.

Biometric authentication uses various aspects of human behavior, chemistry and physiology. Which particular trait will be suitable for the purpose of Biometric authentication depends on several factors. These factors include:

• Universality: A particular trait MUST be present in every single individual who will be using the system.
• Uniqueness: That particular trait in every individual in a group of people must be significantly different so that the individuals can be identified uniquely.
• Permanence: This refers to stability of the trait over time. Any specific trait can vary or fluctuate or may even change permanently over time. So, permanence is a major factor that must be used to weigh a given trait. Any trait with good permanence will stay fairly invariant over a given time span with respect to the matching algorithm used by the system.
• Collectability of Measurability: This refers to the ease with which the trait can be measured.
• Performance: The trait to be used will also depend on how robust, fast and accurate is the technology of the system used.
• Acceptability: All individuals in the given population must accept the technology in a way that they will be willing or ready to have their traits collected and assessed by the technology.
• Circumvention: This refers to the ease with which a particular trait can be duplicated using substitute or artifact.

• Biometric Authentication Process

  Once a particular trait has been selected for a given population, the Biometric authentication process will work in two modes. These two modes are briefly described below:

  Verification Mode

  In this mode, one-on-one comparison of the selected trait is carried out by the system. The trait is compared against a template which is already stored within the Biometric database. The comparison ensures that an individual is really the person who he or she claims to be. The verification mode consists of three steps:

• Step 1: For all individuals in a given population, reference templates/models are first created and then stored in model database.
• Step 2: Threshold is calculated by generating imposter and genuine scores by matching some samples with the reference templates or models.
• Step 3: Template to be used for the comparison is selected in this step, which is the testing step. ID Number, Username or Smart Card may be used for this purpose. The verification mode generally uses “Positive recognition” so that multiple people cannot use the same identity.

• Identification Mode

  In this mode, if the system finds an unidentified individual, it tries to identify the person using “one-to-many comparison”. This comparison takes place against the Biometric database stored in the system. Identification will be successful if and only if the comparison between the sample and the database template falls within the threshold determined previously. Identification mode allows either Positive or Negative recognition.

  Verification can be done using ID Numbers, Username or Smart Card, which can lead to Positive recognition. However, in Identification mode, only and only a Biometric trait can be used for Positive recognition.

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