asp net authentication on mutiple top level domains

Question

I have an asp net mvc application which is on multiple tp level domains:
www.myapp.com
www.myapp.fr
www.myapp.es

I don't find a way to authenticate to all the domains via FormsAuthentication, when I do it for one domain, the cookie is not ok for the other domains

as seen in other questions, it will work for subdomains:
www.myapp.com
fr.myapp.com
es.myapp.com

but not for ccTLD. Is there any clean solution for this ?

Answer 1

The clean solution for this would be to build a passive STS (using WIF) and use this to authenticate all your users.