8. A system for managing access to a plurality of applications comprising: a processor; and an identity service provider executing on the processor, configured to: receive a user name and a user password of a user from a first application; authenticate the user using the user name and password; generate, in response to the successful authentication, identity assertion information comprising information associated with the user for use by a plurality of applications to authenticate the user; generate a first artifact associated with the identity assertion information, wherein the first artifact is used to obtain the identity assertion information; send the first artifact to the first application; receive the first artifact and a request for the identity assertion information from a second application, wherein the second application receives the first artifact from the first application; verify the validity of the first artifact upon receipt from the second application; retrieve, after successful validation of the first artifact, the identity assertion information for the user using the first artifact; send the identity assertion information to the second application, wherein the second application uses the identity assertion information to authorize the user to access the second application; render the first artifact invalid for future use by any of the plurality of applications; receive a request for a second artifact from the second application; and provide the second artifact associated with the identity assertion information, wherein the second artifact is used to obtain the identity assertion information, wherein the first application and the second application are members of the plurality of applications.
8. A system for managing access to a plurality of applications comprising: a processor; and an identity service provider executing on the processor, configured to: receive a user name and a user password of a user from a first application; authenticate the user using the user name and password; generate, in response to the successful authentication, identity assertion information comprising information associated with the user for use by a plurality of applications to authenticate the user; generate a first artifact associated with the identity assertion information, wherein the first artifact is used to obtain the identity assertion information; send the first artifact to the first application; receive the first artifact and a request for the identity assertion information from a second application, wherein the second application receives the first artifact from the first application; verify the validity of the first artifact upon receipt from the second application; retrieve, after successful validation of the first artifact, the identity assertion information for the user using the first artifact; send the identity assertion information to the second application, wherein the second application uses the identity assertion information to authorize the user to access the second application; render the first artifact invalid for future use by any of the plurality of applications; receive a request for a second artifact from the second application; and provide the second artifact associated with the identity assertion information, wherein the second artifact is used to obtain the identity assertion information, wherein the first application and the second application are members of the plurality of applications. 11. The system of claim 8 , wherein the first artifact comprises a type code, a source identification, and an assertion identification.