SSO with CAS or OAuth?

Question

I wonder if I should use the CAS protocol or OAuth + some authentication provider for single sign-on.

Example Scenario:

1. A User tries to access a protec

Answer 1

To me, the real difference between SSO and OAuth is grant, not authentication because a server that implements OAuth obviously has authentication (you have to be logged in to your google, openId or facebook for OAuth to happen with the client app)

In SSO, a power user/sysadmin grants the final user access to an application beforehand on the "SSO app" In OAuth, final user grants application access to his "data" on the "OAuth app"

I don't see why OAuth protocol couldn't be used as part of an SSO server. Just take out the grant screen from the flow and let the OAuth server lookup the grant from the backing db.