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  • 2021-01-22 R&S 2.0 Notes

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  • Andrew Morgan
  • Adam Snook
  • BjOrn Mattsson
  • Alan Buxey
  • Alex Stuart
  • Bas Zoetekouw
  • Christos
  • David St Pierre Bantz
  • Jens Jensen
  • Jri Pavlik
  • Miro
  • Scott Cantor
  • Nicolas Liampotis
  • Heather Flanagan

Agenda

Recap

Identifier issue

From R&S 1.3

Info

where shared user identifier is a persistent, non-reassigned, non-targeted identifier defined to be either of the following:

  1. eduPersonPrincipalName (if non-reassigned)
  2. eduPersonPrincipalName + eduPersonTargetedID

From the eduPerson (202001)

Warning

NOTE: eduPersonTargetedID is DEPRECATED and will be marked as obsolete in a future version of this specification. Its equivalent definition in SAML 2.0 has been replaced by a new specification for standard Subject Identifier attributes [https://docs.oasis-open.org/security/saml-subject-id-attr/v1.0/saml-subject-id-attr-v1.0.html], one of which ("urn:oasis:names:tc:SAML:attribute:pairwise-id") is a direct replacement for this identifier with a simpler syntax and safer comparison rules. Existing use of this attribute in SAML 1.1 or SAML 2.0 should be phased out in favor of the new Subject Identifier attributes."



Issues Raised on Previous Calls

  1. One of the reasons R&S supports ePPN and ePTID is that it was targeting applications that were broken because they only allow for a single identifier to identify an individual (the “one field for everything” approach). That’s why ePPN was the chosen identifier, because it was traditionally a user-friendly identifier and so suitable for the one-size-fits-all use case, as long as you ignore reassignment. ePTID was added to address reassignment. Those applications failed miserably if they only had ePTID.

    Is this still an issue? Do we still need to support the one-size-fits-all approach? If we can chose a common, opaque identifier, with an understanding that you want the additional personalization, we can do that.

    • One opinion: time is right to do this, and R&S is the right place to do this first.
    • Second opinion: this is a question for the SP. Are they ready for R&S to move to a more opaque identifier? There’s no incentive for an IdP to make their identifier better unless there’s a demand by the SPs.
      • Based on the responses from the SPOG list, SPs do not handle identifier reassignment in any standardized manner. The level of automation in responding to this seems to depend entirely on the size of the SP and how big their IT budget is
  2. Providing a migration path for changes in R&S


Notes

If the requirement is to have an single identifier that is user friendly and able to route email, then there are no changes we can make here, and we need to convince people to not reassign it. There is also concerns that it will be too difficult to change this because of existing implementations, because implementations will need to re-key. If we are going to change it, we do have a clear target to move to.

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