Reliable authorization and authentication are becoming necessary for many

everyday applications such as boarding an aircraft, performing financial transaction,

logging to a secure system etc. Identity verification becomes a challenging task when

it has to be automated with high accuracy and with low probability of break-ins and

low rates of false match. Moreover, person verification is not a new problem and

society had created three traditional modes of designation:

1. Possessions: Physical possessions such as keys, passports and smart cards.

2. Knowledge: Pieces of information those are secret and known only to the right

person such as PIN, passwords, user names etc.

3. Biometrics: Physiological and behavioral characteristics of individuals that

distinguish one person from the others. These characteristics are different in

each person.