I have gone over the plethora of ASP.NET single sign on info on the internet (most of which seems to be the same copy and pasted advice), however the solutions presented should more properly be called "domain-wide sign on". They all involve providing a cookie with blanket domain-wide access to the user.
This requires that you use the same applicationName and applicationId on every website, so from the ASP.NET security perspective, you are essentially only signing on to one application, not using one login for multiple applications as might be implied.
The problem here is if you have 3 applications and you only want a certain user to have access to 2 of those applications while others have access to all 3, the common "single sign on" method fails. Technically, you could restrict access by role, however this requires you to manually configure web.config files whenever you deploy a new site and this is a rather crude solution, especially if y ...
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