Biometric technologies are defined as automated methods of identifying or authenticating the identity of a living person based on unique physiological or behavioral characteristics. Biometrics can provide very secure and convenient authentication for an individual since they cannot be stolen or forgotten and are very difficult to forge.

Reliable user authentication is becoming an increasingly important task in the Web-enabled world. The consequences of an insecure authentication system in a corporate or enterprise environment can be catastrophic, and may include loss of confidential information, denial of service, and compromised data integrity. The value of reliable user authentication is not limited to just computer or network access. Many other applications in everyday life also require user authentication, such as banking, e- commerce, and physical access control to computer resources, and could benefit from enhanced security.

The prevailing techniques of user authentication, which involve the use of either passwords and user IDs (identifiers), or identification cards and PINs (personal identification numbers), suffer from several limitations. Passwords and PINs can be illicitly acquired by direct covert observation. Once an intruder acquires the user ID and the password, the intruder has total access to the user’s resources. In addition, there is no way to positively link the usage of the system or service to the actual user, that is, there is no protection against repudiation by the user ID owner.

For example, when a user ID and password is shared with a colleague there is no way for the system to know who the actual user is. A similar situation arises when a transaction involving a credit card number is conducted on the Web. Even though the data are sent over the Web using secure encryption methods, current systems are not capable of assuring that the rightful owner of the credit card initiated the transaction. In the modern distributed systems environment, the traditional authentication policy based on a simple combination of user ID and password has become inadequate. Fortunately, automated biometrics in general, and fingerprint technology in particular, can provide a much more accurate and reliable user authentication method. Biometrics is a rapidly advancing field that is concerned with identifying a person based on his or her physiological or behavioral characteristics. Examples of automated biometrics include fingerprint, face, iris, and speech recognition.

A physiological characteristic is a relatively stable physical characteristic, such as an individual’s fingerprint, hand geometry, iris pattern, or blood vessel pattern on the back of the eye. This type of biometric measurement is usually unchanging and unalterable without significant duress to the individual.

A behavioral characteristic is more a reflection of an individual’s psychological makeup. A signature is the most common behavioral biometric used for identification. Because most behavioral characteristics vary over time, an identification system using these must allow updates to enrolled biometric references.