SSO via encrypted token
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We have the need in a project to implement single sign-on for two different web applications, one being our own and one is implemented by someone else. For our own application we have user/password stored (encrypted) in the database. Since our application will be integrated in their environment, we now need a mechanism to let us authorize the user already being logged in at their side without showing a login screen again.

Since I'm not a security expert myself, I started reading (on a high-level) about a few techniques regarding SSO, e.g. OpenID, Kerberos, SAML, CAS - but I have not yet gained practical experience. 

Before marching in the wrong direction - can someone provide me with own experience in that field and point me to a framework to use or a good (and recent) article about how this should be done?

One more infomation: The customer talks about preferring to pass encrypted tokens between the two webapps. Does this make sense? And does this lead to a certain technique? 
