Consider the many times an individual accesses services on the Internet in a single day. At work, he uses the company intranet to perform a multitude of business-related tasks such as reading and sending email, looking up information in the company phone book and other internal databases, and submitting expense reports and other business-related online forms. At home after work, he checks his personal email, then logs into an online news service to check his baseball team’s standings. He may finalize his travel plans via his travel agent’s website, and then does some online shopping at his favorite clothing store. Each time he accesses a service on the Internet, he must log in and identify himself to the service provider.
A local identity refers to the set of attributes or information that identify a user to a particular service provider. These attributes typically include a name and password, plus an email address, account number or other identifier. For example, the individual in our scenario is known to his company’s network as an employee number, but he is known to his travel agent as Joe Smith. He is known as an account number to the car rental agency he uses frequently. He is known to his favorite airline by a different account number. He uses one email name and address for his personal email, and a different email name and address for his workplace. Each of these different user names represents a different local identity.
Identity federation allows a user to consolidate the many local identities he has configured among multiple service providers. With one federated identity, the individual can log in at one service provider’s site and move to an affiliated service provider site without having to re-authenticate or re-establish his identity. For example, with a federated identity, the individual might want to access both his personal email account and his business email account from his workplace, and move back and forth between the two services without having to log in each time. Or at home he might want to log in to an online travel agency, then book airline tickets online, and make hotel reservations online. It is a convenience for the user to be able to access all of these services without having to provide different user names and passwords at each service site. It is a valuable benefit to the user when he can do so safely, and knowing that his identity information is secure.
The Liberty Alliance Project was implemented to make this possible.