[Sign In] Redirect based SSO - User already signed in RP1, need to SSO in RP2 - both RP1 and RP2 trust IDP1 about docs HOT 2 CLOSED

Do we need a use case document for each protocol? Also, seemless/silent SSO requires some mechanism for shared state. Do we need a use case for each of those mechanisms?

I'm working on a scenario for redirects where all properties are on the eTLD+1 and "logged-in flag" can be shared via a cookie on the eTLD+1.

This could also be accomplished by RP2 doing a redirect with prompt=none to IDP1 whenever the user arrives.

Additionally, I think this can be done with embedded iframes where the iframe is sourced from IDP1. I'm less familiar with this method.

Other options?

from docs.

migrated from: fedidcg/protocol-library#12

from docs.