1. A token-based centralized authentication method for providing access to a service provider to user information associated with a user's relationship with the service provider, comprising the steps of: authenticating a user presenting a user token at a user terminal, the user token having stored thereon a user ID; deriving a resource identifier using at least two data input elements, the at least two data input elements including the user ID of the user and a service provider ID of the service provider, wherein the user information is stored in a storage network and the resource identifier is associated with the user information; retrieving the user information from the storage network using the resource identifier; and providing the retrieved user information to the service provider.