Single sign-on with common access card

A mechanism eliminates the number of times a user must login to individual services after initially logging into a computer system. A user only logs once into a computer system, and subsequent login requests by multiple services are handled automatically and transparently by the system. In one implementation, a user need only present a card to a card reader and enter a PIN, and the user is logged-in after presenting the card and a valid PIN. The system generates a token that is valid for this particular login session of the user, and when the user accesses a permissioned service, the system automatically logs-in the user to the application using the token. The system can perform the automatic login for the user to a variety of applications including legacy applications, web-enabled applications, and commercial, off-the-shelf applications.