EPPN and eduPersonTargetedID

[Eric Goodman]

>> Is the eduPersonTargetedID always guaranteed to be unique and stable?

>The value of ePTID together with the IdP entityID is globally unique.
>If by "stable" you mean "unlikely to change," the answer is yes (but 
>there is no guarantee that ePTID will persistent indefinitely). More 
>importantly, ePTID is guaranteed to be non-reassigned.

Within the UC System, I know that at least some of the IdPs generate ePTIDs based on a dynamic hash of some attribute and the SP name. What that means is that if the "some attribute" changes then the presumption of persistence -- and possibly non-reassignability -- is lost. 

Basically, I'm saying that Tom gave you the standards-based answer; the pragmatic answer might be subtly different.

I recognize that your questions may be targeted at a broader net than just UC, but I'm guessing that we're at least some of your customers of concern. :) I do periodically survey UC locations to get answers to operational questions like these (independent of what the standard claims to require). I don't think I've ever done such a survey on the ePTID attribute in particular, but I can if that would be useful. 

[For longtime readers, this post is basically my ongoing "ForceAuthn issues" commentary translated to ePTID values... :)]

--- Eric