[Anima] Discovery of renewal server / draft-eckert-anima-brski-discovery / draft-ietf-anima-brski-ae / draft-ietf-anima-brski-prim

[Toerless Eckert <[e-mail]>]

Revisiting the constrained BRSKI discovery details, i stumbled across a generic discovery
issue for which i would like to solicit opinions.

Please also add your thoughts about this to:
  https://github.com/anima-wg/brski-discovery/issues/4
  (but discuss here first).

Question: How do we want to deal with certificate renewal/re-keying ?

Do we assume by default that any discovered BRSKI (variation) proxy/registar is
capable to do renewal ? Technically this would not require new REST endpoints with
EST, but i am not sure this is true across all alternative enrollment protocols.
Is renewal working with PRM without changes ? (If so we should write this).

When writing RFC8994, we did consider that not all existing EST servers would
necessarily support BRSKI, and therefore instead of using AN_join_registrar, renewal
was recommend to use SRV.est objective. We did not define an equvalent proxy objective
though, because already enrolled pledges would not need to use a proxy but could
always connect directly to a registrar.

Do we ever need renewal to go through a proxy ? 

Thanks
    Toerless