Biometric Systems provide improved security over traditional electronic access control methods such as RFID tags, electronic keypads and some mechanical locks. The user's authorized card or password pin can be lost or stolen. In order for the biometrics to be ultra-secure and to provide more-than-average accuracy, more than one form of biometric identification is required. Hence the need arises for the use of multimodal biometrics. This uses a combination of different biometric recognition technologies. This chapter begins with the basic idea of Biometrics, Biometrics System with its components, Working and proceeds with the need of Multimodal Biometrics with the emphasis on review of various multimodal systems based on fusion ways and fusion level of various features. The last section of this chapter describes various multimodal Biometric Systems.
TopIntroduction
In an identity management system like banking site log in, ATM login, Airport verification for a traveler, traditional token based user verification methods based on license, passport, PINS or passwords prove as weak authentication methods since they can be missed or stolen. Authentication measure is thus required to exist with user, not lost in any case and must be unique of course! Such a reliable measure is nothing but the person itself!, Here the term biometrics came into existence.
The term Biometrics contains two words − Bio (Greek word for Life) and Metrics (Measurements). Biometrics is a branch of information technology that aims towards finding one’s identity based on personal traits. Biometric systems are developed based on the individual’s physical characteristics or behavioral characteristics. The physical characteristics or features or attributes like finger prints, color of iris, color of hair, hand geometry, and behavioral characteristics such as tone and accent of speech, signature, etc. make a person stand separate from the rest.
These are the unique characteristics which are selected. This means that we should have feel of uniqueness when we look at the object. Not only one part should be different but together the entire object must be found unique. Also it is necessary that it should be existing with everybody.
Biometric systems use these unique features for:
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Identification and verification of a person,
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Authentication of person,
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Security of system from unauthorised access.
A biometric system is a technology which takes input as person’s physiological, behavioral, or both traits as input, analyzes it, and authenticate the person for accessing the system.
TopComponents Of A Biometric System
In general, a biometric system can be divided into four basic components (Figure 1).
Figure 1. Components of biometric system
- 1.
Input Interface (Sensors): It is the sensing component of a biometrics system that converts human biological data into digital form. For example,
- a.
A Metal Oxide Semiconductor (CMOS) imager or a Charge Coupled Device (CCD) in the case of face recognition, handprint recognition, or iris/retinal recognition systems.
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An optical sensor in case of fingerprint systems.
- c.
A microphone in case of voice recognition systems.
- 2.
Processing Unit: The processing component is a microprocessor, Digital Signal Processor (DSP), or computer that processes the data captured from the sensors. The processing of the biometric sample involves:
- a.
Sample image enhancement,
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Sample image normalization,
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Feature extraction,
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Comparison of the biometric sample with all stored samples in database.
- 3.
Database Store: The database stores the enrolled sample, which is recalled to perform a match at the time of authentication. For identification, there can be any memory from Random Access Memory (RAM), flash EPROM, or a data server. For verification, a removable storage element like a contact or contactless smart card is used.
- 4.
Output Interface: The output interface communicates the decision of the biometric system to enable the access to the user. This can be a simple serial communication protocol RS232, or the higher bandwidth USB protocol. It could also be TCP/IP protocol, Radio Frequency Identification (RFID), Bluetooth, or one of the many cellular protocols.