Hi Thom,

Your presentation today was good, but I just want to point out an elephant in 
the room that's missing from your slides: Public PKI is not currently equipped 
to issue KEM certificates because every cert enrollment protocol that I can 
think of uses CSRs at the bottom, and you can't sign a CSR with a KEM key. Back 
in 2021 I did some digging into which PKI enrollment protocols have 
Proof-of-Possession (PoP) mechanisms for encryption keys, which I presented at 
the Jan 2021 LAMPS Interim - see Slide 27 [1]; missing from that slide is: 
"ACME: No". If tls-authkem progresses, then we as a community need to have a 
whole debate about how much we care about PoP for cert enrollment and whether 
we're ok for CAs to accept un-protected CSRs (just nothing in the signature 
field), or whether we want to go down the rabbit hole of Zero Knowledge Proof 
based CSR protection such as the one proposed in [2], or re-design cert 
enrollment protocols to protect KEM CSRs in some other way (like CSRs signed 
with the ACME account key).

I am not trying to slow down draft-tls-authkem because it's good work, but 
please don't overlook that WebPKI is not currently equipped to issue KEM 
certificates and there is a fairly large amount of pre-requisite work that 
would need to happen before we can deploy tls-authkem at any kind of scale.

[1]: 
https://datatracker.ietf.org/doc/slides-interim-2021-lamps-01-sessa-position-presentation-by-mike-ounsworth/
[2]: https://dl.acm.org/doi/abs/10.1145/3548606.3560560

---
Mike Ounsworth
Software Security Architect, Entrust

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