This document is an attempt to clarify the R&S specification to address issues that have arisen in its initial deployment by federations, particularly confusion over its relationship to other, unrelated mechanisms and regimes for attribute release faciliationfacilitation. It also attempts to clarify what an SP and IdP are obligated or assumed to be doing, and moves some "implicit" guidance into formally suggested behavior.
Service Providers are strongly encouraged to support all of the specified alternatives for the shared user identifier and person name attributes described in Section 5 to maximize interoperability. Failure to do so will result in problems even when working exclusively with Identity Providers that claim support for the category.
In the case of the
eduPersonTargetedID attribute, this recommendation includes the ability to support SAML 2.0's "persistent" Name Identifier format, which is the recommended modern expression of the
eduPersonTargetedID attribute in SAML 2.0.
In accordance with the requirements in Section 7, if an Identity Provider exhibits the R&S entity attribute in its metadata and no accompanying
eduPersonTargetedID attribute is recieved, then Service Providers can rely on the non-reassignment of
eduPersonPrincipalName values it receives from that Identity Provider.
Alternatively, Service Providers can obtain a non-reassigned shared user identifier by combining (e.g., concatenating) the
eduPersonTargetedID values. If a given combination of the two values ever changes, Service Providers can assume that the
eduPersonPrincipalName has been reassigned and now represents a different subject.