Date Added: Apr 2012
User authentication is a key security process that either allows or denies access to a system or resource depending on the credentials presented. The credentials that the user presents may be classified under three main categories - what you know (token-based), what you have (knowledge-based), and who you are (biometric-based). The token based authentication system is a two factor system makes use of the pin number and the physical card to operate it. The card and pin number should be secured enough and memorisable. Text and graphical passwords comes under knowledge-based authentication system.