Biometric Systems

Biometrics as most of us know is a set of techniques that verifies the identity of a user based upon his unique physiological characters.
Different types of devices are used to scan different body parts, and verifies the scan to the one recorded in the refrence file. Once the pattern is matched, the user is allowed to access the facility or the system.
Since biometric systems need to match the scan to the database, they may need to scan the person more than once in order to store a correct record, or to verify it correctly. This may take time and may prove to be very intrusive to the users. Biometric systems are also prone to making mistakes while comparing the scans. A term called as the Crossover Error Rate (CER) of the Biometric system tells how accurate that system is. CER is the oint on the graph at which the False Rejection Rate (FRR) meets the False Acceptance Rate (FAR).
FRR value shows the number of times a given system may reject an authorized user as unauthorized in a given span.
FAR value specifies how many time a system may accept an unauthorized person as authorized in a given span.
The lower the CER value, the more accurate the biometric system is.
i.e. a Biometric System with a CER of 3 is likely to be more accurate than that having a CER of 4.
The different characteristics that are used in Biometrics to identify users are:
1. Fingerprint – checks for specific pattenrs if ridges and bifurcations  and detailed chataceristics called minutiae.
2. Palm Scan – examines the creases, ridges and grooves on the palm of the user.
3. Hand Geometry – examines the shape (length and width of the hand and fingers).
4. Hand Topoloy – examines the side-view picture of the hand looking at the peaks and valleys of the hand.
5. Retina scan – examines the patterns of blood vessels of the retina at the backside of the eye
6. Iris scan – examines the colored portion of the eye surrounding the pupil.
7. Voice Print – examines the voice of the person when he speaks a set of words given to him in different jumbled orders.
8. Facial Scan – Scans the entire face of the user for different bone structures, nose ridges, eye widths, chin shape and forehead shape.
9. Signature Dynamics – examins the way a person holds a pen while signing, speed of signing, pressure exerted on teh pen etc.
10. Keystroke Dynamics –  Speed of typing on the keyboard, hold time and flight time etc.

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