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Biometric Dictionary
I.Biometric Terms Part I. Biometric Terms Active Impostor Acceptance When an impostor submits a modified, simulated or reproduced biometric sample, intentionally attempting to relate it to another person who is an enrollee, and he/she is incorrectly identified or verified by a biometric system as being that enrollee. Compare with 'Passive Impostor Acceptance'. Application Developer An individual entrusted with developing and implementing a biometric application. Attempt The submission of a biometric sample to a biometric system for identification or verification. A biometric system may allow more than one attempt to identify or verify. Authentication The preferred biometric term is 'Verification'. Automatic ID/Auto ID An umbrella term for any biometric system or other security technology that uses automatic means to check identity. This applies to both one-to-one verification and one-to-many identification. Behavioral Biometric A biometric which is characterized by a behavioral trait that is learnt and acquired over time rather than a physiological characteristic. See Part III Terms Related to Specific Biometric Techniques for 'Keystroke Dynamics', 'Signature Verification', and 'Speaker Verification'. Contrast with 'Physical/Physiological Biometric'. Biometric A measurable, physical characteristic or personal behavioral trait used to recognize the identity, or verify the claimed identity, of an enrollee. Biometric Application The use to which a biometric system is put. See also 'Application Developer'. Biometric Data The extracted information taken from the biometric sample and used either to build a reference template or to compare against a previously created reference template. Biometric Engine The software element of the biometric system which processes biometric data during the stages of enrollment and capture, extraction, comparison and matching. Biometric Identification Device The preferred term is 'Biometric System'. Biometric Sample Data representing a biometric characteristic of an end-user as captured by a biometric system. Biometric System An automated system capable of: 1.capturing a biometric sample from an end user; 2.extracting biometric data from that sample; 3.comparing the biometric data with that contained in one or more reference templates; 4.deciding how well they match; and 5.indicating whether or not an identification or verification of identity has been achieved. Biometric Taxonomy A method of classifying biometrics. For example, San Jose State University's (SJSU) biometric taxonomy uses partitions to classify the role of biometrics within a given biometric application. Thus an application may be classified as: Cooperative vs. Non-Cooperative User Overt vs. Covert Biometric System Habituated vs. Non-Habituated User Supervised vs. Unsupervised User Standard Environment vs. Non Standard Environment Biometric Technology A classification of a biometric system by the type of biometric. Capture The method of taking a biometric sample from the end user. Certification The process of testing a biometric system to ensure that it meets certain performance criteria. Systems that meet the testing criteria are said to have passed and are certified by the testing organization. Comparison The process of comparing a biometric sample with a previously stored reference template or templates. See also 'One-To-Many' and 'One-To-One'. Claim of Identity When a biometric sample is submitted to a biometric system to verify a claimed identity. Claimant A person submitting a biometric sample for verification or identification whilst claiming a legitimate or false identity. Closed-Set Identification When an unidentified end-user is known to be enrolled in the biometric system. Opposite of 'Open-Set Identification'. Crossover Rate Synonym for 'Equal Error Rate'. D Prime A statistical measure of how well a biometric system can discriminate between different individuals. The larger the D Prime value, the better a biometric system is at discriminating between individuals. Degrees of Freedom The number of statistically independent features in biometric data. Discriminant Training A means of refining the extraction algorithm so that biometric data from different individuals are as distinct as possible. End User A person who interacts with a biometric system to enroll or have his/her identity checked. End User Adaptation The process of adjustment whereby a participant in a test becomes familiar with what is required and alters their responses accordingly. Enroll A person who has a biometric reference template on file. Enrolment The process of collecting biometric samples from a person and the subsequent preparation and storage of biometric reference templates representing that person's identity. Enrolment Time The time a person must spend to have his/her biometric reference template successfully created. Equal Error Rate When the decision threshold of a system is set so that the proportion of false rejections will be approximately equal to the proportion of false acceptances. A synonym is 'Crossover Rate'. Extraction The process of converting a captured biometric sample into biometric data so that it can be compared to a reference template. Failure to Acquire Failure of a biometric system to capture and extract biometric data. Failure to Acquire Rate The frequency of a failure to acquire. False Acceptance When a biometric system incorrectly identifies an individual or incorrectly verifies an impostor against a claimed identity. Also known as a Type II error. False Acceptance Rate/FAR The probability that a biometric system will incorrectly identify an individual or will fail to reject an impostor. Also known as the Type II error rate. It is stated as follows: FAR = NFA / NIIA or FAR = NFA / NIVA where FAR is the false acceptance rate NFA is the number of false acceptances NIIA is the number of impostor identification attempts NIVA is the number of impostor verification attempts
False Match Rate Alternative to 'False Acceptance Rate'. Used to avoid confusion in applications that reject the claimant if their biometric data matches that of an enrollee. In such applications, the concepts of acceptance and rejection are reversed, thus reversing the meaning of 'False Acceptance' and 'False Rejection'. See also 'False Non-Match Rate'. False Non-Match Rate Alternative to 'False Rejection Rate'. Used to avoid confusion in applications that reject the claimant if their biometric data matches that of an enrollee. In such applications, the concepts of acceptance and rejection are reversed, thus reversing the meaning of 'False Acceptance' and 'False Rejection'. See also 'False Match Rate'. False Rejection When a biometric system fails to identify an enrollee or fails to verify the legitimate claimed identity of an enrollee. Also known as a Type I error. False Rejection Rate/FRR The probability that a biometric system will fail to identify an enrollee, or verify the legitimate claimed identity of an enrollee. Also known as a Type I error rate. It is stated as follows: FRR = NFR / NEIA or FRR = NFR / NEVA where FRR is the false rejection rate NFR is the number of false rejections NEIA is the number of enrollee identification attempts NEVA is the number of enrollee verification attempts Field Test A trial of a biometric application in 'real world' as opposed to laboratory conditions. Goats Biometric system end users whose pattern of activity when interfacing with the system varies beyond the specified range allowed by the system, and who consequently may be falsely rejected by the system. Genetic Penetrance The degree to which characteristics are passed from generation to generation. Identification/Identify The one-to-many process of comparing a submitted biometric sample against all of the biometric reference templates on file to determine whether it matches any of the templates and, if so, the identity of the enrollee whose template was matched. The biometric system using the one-to-many approach is seeking to find an identity amongst a database rather than verify a claimed identity. Contrast with 'Verification'. Impostor A person who submits a biometric sample in either an intentional or inadvertent attempt to pass him/herself off as another person who is an enrollee. In-House Test A test carried out entirely within the environs of the biometric developer which may or may not involve external user participation. Live Capture The process of capturing a biometric sample by an interaction between an end user and a biometric system. Match/Matching The process of comparing a biometric sample against a previously stored template and scoring the level of similarity. An accept or reject decision is then based upon whether this score exceeds the given threshold. One-To-Many Synonym for 'Identification'. One-To-One Synonym for 'Verification'. Open-Set Identification Identification, when it is possible that the individual is not enrolled in the biometric system. Opposite of 'Closed-Set Identification'. Out Of Set In open-set identification, when the individual is not enrolled in the biometric system. Passive Impostor Acceptance When an impostor submits his/her own biometric sample and claiming the identity of another person (either intentionally or inadvertently), he/she is incorrectly identified or verified by a biometric system. Compare with 'Active Impostor Acceptance'. Performance Criteria Pre-determined criteria established to evaluate the performance of the biometric system under test. Physical/Physiological Biometric A biometric which is characterized by a physical characteristic rather than a behavioral trait. See Part III Terms Related to Specific Biometric Techniques for 'Body Odor', 'Ear Shape', 'Face Recognition', 'Finger Geometry','Finger Image', 'Hand Geometry', 'Iris Recognition', 'Palm', 'Retina', 'Speaker Verification' and 'Veincheck'. Contrast with 'Behavioral Biometric'. Receiver Operating Curves A graph showing how the false rejection rate and false acceptance rate vary according to the threshold. Recognition The preferred term is 'Identification'. Response Time The time period required by a biometric system to return a decision on identification or verification of a biometric sample. Template/Reference Template Data, which represents the biometric measurement of an enrollee, used by a biometric system for comparison against subsequently submitted biometric samples. Third Party Test An objective test, independent of a biometric vendor, usually carried out entirely within a test laboratory in controlled environmental conditions. Threshold/Decision Threshold The acceptance or rejection of biometric data is dependent on the match score falling above or below the threshold. The threshold is adjustable so that the biometric system can be more or less strict, depending on the requirements of any given biometric application. Throughput Rate The number of end users that a biometric system can process within a stated time interval. Type I Error See 'False Rejection'. Type II Error See 'False Acceptance'. User The client to any biometric vendor. The user must be differentiated from the end user and is responsible for managing and implementing the biometric application rather than actually interacting with the biometric system. Validation The process of demonstrating that the system under consideration meets in all respects the specification of that system. The process of comparing a submitted biometric sample against the biometric reference template of a single enrollee whose identity is being claimed, to determine whether it matches the enrollee's template. Contrast with 'Identification'. Zero
Effort Forgery An arbitrary attack on a specific enrollee
identity in which the impostor masquerades as the claimed enrollee using
his or her own biometric sample. Algorithm A sequence of instructions that tell a biometric system how to solve a particular problem. An algorithm will have a finite number of steps and is typically used by the biometric engine to compute whether a biometric sample and template are a match. See also 'Artificial Neural Network. API (Application Program Interface) A set of services or instructions used to standardize an application. An API is computer code used by an application developer. Any biometric system which is compatible with the API can be added or interchanged by the application developer. See also Part III Terms Related to Specific Biometric Techniques for 'SVAPI' under 'Speaker Verification'. Artificial Neural Network A method of computing a problem. An artificial neural network uses artificial intelligence to learn by past experience and computer whether a biometric sample and template are a match. See also 'Algorithm'. ASIC (Application Specific Integrated Circuit) An integrated circuit (silicon chip) that is specially produced for a biometric system to improve performance. CMOS (Complementary Metal Oxide Semiconductor) A type of integrated circuit used by some biometric systems because of its low power consumption. Encryption The act of converting biometric data into a code so that people will be unable to read it. A key or a password is used to decrypt (decode) the encrypted biometric data. Hamming Distance The number of disagreeing bits between two binary vectors. Used as measure of dissimilarity. Neural Net/Neural Network Synonym for 'Artificial Neural Network'. OEM (Original Equipment Manufacturer/Module) A biometric organization (Manufacturer) which assembles a complete biometric system from parts; or a biometric Module for integration into a complete biometric system. PIN (Personal Identification Number) A security method whereby a (usually) four digit number is entered by an individual to gain access to a particular system or area. WSQ (Wavelet Transform/Scalar Quantisation) A compression algorithm used to reduce the size of reference templates.
Terms relating to specific biometric technologies and techniques are grouped below. 1.AFIS
(Automated Fingerprint Identification System) 1. AFIS (Automated Fingerprint Identification System) A highly specialized biometric system that compares a single finger image with a database of finger images. AFIS is predominantly used for law enforcement, but is also being put to use in civil applications. For law enforcement, finger images are collected from crime scenes, known as latents, or are taken from criminal suspects when they are arrested. In civilian applications, finger images may be captured by placing a finger on a scanner or by electronically scanning inked impressions on paper. See also Part III Biometric Specific Terms number 6, Finger Image. Binning A specialized technique used by some AFIS vendors. Binning is the process of classifying finger images according to finger image patterns. This predominantly takes place in law enforcement applications. Here finger images are categorized by characteristics such as arches, loops and whorls and held in smaller, separate databases (or bins) according to their category. Searches can be made against particular bins, to speeding up the response time and accuracy of the AFIS search. Booking The process of capturing inked finger images on paper, for subsequent processing by an AFIS. Filtering A specialized technique used by some AFIS vendors. Filtering is the process of classifying finger images according to data, which is unrelated to the finger image itself. This may involve filtering by sex, age, hair color, or other distinguishing factors. Latent An impression of a finger image collected from a crime scene. 2. Body Odor A physical biometric that analyses the unique chemical pattern made up by human body smell. Volatiles The chemical breakdown of body odor. 3. DNA DNA is a unique, measurable human Characteristic. However, current DNA technology is not automatic and cannot currently rank alongside other biometric technologies. 4. Ear Shape A lesser-known physical biometric that is characterized by the shape of the outer ear, lobes and bone structure. 5. Face Recognition A physical biometric that analyses facial features. Eigenface A method of representing a human face as a linear deviation from a mean or average face. Eigenhead The three-dimensional version of Eigenface that also analyses the shape of the head. Face Monitoring A biometric application of face recognition technology where the biometric system monitors the attendance of an end user at a desktop. Facial Thermogram A specialized face recognition technique that senses heat in the face caused by the flow of blood under the skin. 6. Finger Image A physical biometric, which looks at the patterns, found in the tip of the finger. Auto-correlation A proprietary fingerscanning technique. Two identical finger images are overlaid in the auto-correlation process, so that light and dark areas, known as Moiré fringes, are created. Bifurcation A branch made by more than one finger image ridge. Capacitance A finger image capture technique that senses an electrical charge, from the contact of ridges, when a finger is placed on the surface of a sensor. A measurement of resolution for finger image biometrics. Fingerprint/Fingerprinting The preferred terms are now 'Finger Image' and 'Fingerscanning'. Fingerscanning The process of finger image capture. Live Scan The term live scan is typically used in conjunction with finger image technology. Synonym for 'Live Capture'. See Part I. General Biometric Terms. Minutiae Small details found in finger images such as ridge endings or bifurcation's. Optical A finger image capture technique that uses a light source, a prism and a platen to capture finger images. Platen The surface on which a finger is placed during optical finger image capture. Ridge The raised markings found across the fingertip. See also 'Valley'. Ridge Ending The point at which fingers image ridge ends. Ultrasound A technique for finger image capture that uses acoustic waves to measure the density of a finger image pattern. Thermal A finger image capture technique that uses a sensor to sense heat from the finger and thus capture a finger image pattern. Valley The corresponding marks found on either side of a finger image ridge. 7. Finger Geometry A physical biometric that analyses the shape and dimensions of one or more fingers. 8. Hand Geometry/Hand Recognition A physical biometric that involves analyzing and measuring the shape of the hand. 9. Iris Recognition A physical biometric that analyses iris features found in the colored ring of tissue that surrounds the pupil. Iris Features A number of features can be found in the iris. These are named corona, crypts, filaments, freckles, pits, radial furrows, and striations. IrisCode The biometric data that is generated for each live iris presented. The code is a mathematical representation of the features of the iris. See also 'Biometric Data'. 10. Keystroke Dynamics A behavioral biometric under development that analyses typing rhythm when an end user types onto a keyboard. 11. Palm A physical biometric that analyses the palm of the hand. Typically, this will involve an analysis of minutiae data. 12. Retina A physical biometric that analyses the layer of blood vessels situated at the back of the eye. 13. Signature Verification A behavioral biometric that analyses the way an end user signs his/her name. The signing features such as speed, velocity, and pressure exerted by a hand holding a pen are as important as the static shape of the finished signature. Acoustic
Emission A proprietary technique used in signature verification.
As a user writes on a paper surface, the movement of the pen tip over
the paper fibers generates acoustic emissions that are transmitted in
the form of stress waves within the material of a writing block beneath
the document being signed. The structure-borne elastic waves behave
in materials in a similar way to sound waves in air and can be detected
by a sensor attached to the writing block. 14. Speaker verification A part physical, part behavioral biometric that analyses patterns in speech. Fixed-Text System The preferred term is 'Text-Dependent System'. Free-Text System. The preferred term is 'Text-Independent System'. Speaker-Dependent A term sometimes used by speaker verification vendors to emphasize the fact their technology is designed to distinguish among voices. Speaker Separation A technology that separates overlapping voices from each other and other background noises. Speech Recognition This is not a biometric and should not be confused with speaker verification. Speech recognition involves recognizing words as they are spoken and does not identify the speaker. SVAPI (Speaker Verification Application Program Interface) A biometric API for speaker verification systems. Text-Dependent System A system that requires a speaker to say a specific set of numbers or words. Text-Independent System A system that creates voiceprints from unconstrained speech and does not require a speaker to say a specific set of numbers or words. Text-Prompted System A speaker verification system that prompts the speaker to say randomly ordered numbers or words. The term 'Challenge-Response' is also used in a similar way to define text prompting. Voice Verification The preferred term is 'Speaker Verification'. Voice Print/Voiceprint A representation of the acoustic information found in the voice of a speaker. 15. Veincheck/Vein Tree A physical biometric under development that analyses the pattern of veins in the back of the hand.
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