Authentication is the demonstration of credentials that indicate the user is who he or she claims to be. As the practical repository for enterprise data, network services must be able to adequately maintain the security of network data by limiting access to authorized users. These users validate their identities through authentication prompts and, provided the authentication credential is provided, are granted access. In many cases, it's unwise user tendencies that make password authentication vulnerable. For example, many users set up passwords that are easy to guess.
Some users have their passwords noted in plain view of others on a sticky note on their monitor.
For these reasons, and others, many organizations have decided to adopt strong authentication methods such as smart cards, physical tokens, biometrics, and PKI systems using X.509 certificates. Token authentication systems are based on various schemes. Biometric authentication involves providing a unique physical characteristic that distinguishes one user from another. These characteristics might be a fingerprint, voice, handwriting, facial features, eye or retina scan, etc. Biometric characteristics are measured using sensors that produce data values that can then be processed by a computer using specialized algorithms for analysis and comparison against a known data value sample.