Use Seamless Access for authentication
Seamless Access is a new tool for Single sign-on authentication, this is how they describe it:
SeamlessAccess enables true Single Sign-On. Your users will be able to sign in using their preferred sign in credentials, and will not be bothered for them again for all SeamlessAccess-enabled sites.
Sounds like a great idea as long as user privacy is protected.
Arianna Schlegel commented
I don't have any votes left at the moment, but I do think this is valuable to explore. Thank you, Eva!