Patent ID: 8276190

Claim:
A method of authenticating a user to a web service in a second domain, the user using a browser having a stored browser authentication cookie issued by a web service in a first domain, wherein the first domain and the second domain are different second-level Internet domains, and wherein the browser is configured to prevent the web service in the second domain from accessing a cookie created by the web service in the first domain, the method comprising: the web service in the second domain providing the browser with computer program instructions causing the browser to transparently: provide the stored browser authentication cookie to the web service in the first domain; receive, responsive to successful validation of the browser authentication cookie by the web service in the first domain, cross-domain authentication credentials from the web service in the first domain; and provide the cross-domain authentication credentials to the web service in the second domain; validating the cross-domain authentication credentials; and providing the user with authenticated access to the web service in the second domain responsive at least in part to successful validation of the cross-domain authentication credentials.