Hi Thom,

On Thu, 2022-10-06 at 12:07 +0200, Thom Wiggers wrote:

Thanks for your email; you sent it right on time as I'd just started composing 
a similar email based on my reading of section 4.2 of RFC4211.

Op do 6 okt. 2022 om 09:58 schreef Thom Wiggers 
<[email protected]<mailto:[email protected]>>:

We weren't aware of CRMF, so it seems I've got some reading to do as I write 
some paragraphs on KEM certificates in my PhD thesis :)

Digging into RFC4211 and as David just wrote, my interpretation of the 
"indirect method" specified there mostly lines up with the "encrypt 
certificate" approach I described in my previous email. CRMF, as an interactive 
protocol, does require that you prove to the issuer that you decrypted 
correctly, as David wrote, so I suppose that this makes it important that the 
protocol that implements CRMF delays submitting to the CT logs until after 
they've received confirmation, to avoid the "attack" that I described.

Yes.
The 2nd round trip using CMP certConf/pkiConf messages usually is done already 
for a reason that applies to all key types:
to confirm to the CA that the EE received the new cert and is happy with it. 
Only then should the cert be published and used.
This is something not supported by a simple round trip (including the typical 
use of PKCS #10 CSRs), which you referred to as "non-interactive" issuance.


Of course, that still means that the "encrypt certificate" message does not 
work for the kinds of "non-interactive" issuance that CSRs allow.

Please note that the term CSR is actually broader that just PKCS #10 - it 
applies also to other formats, such as CRMF.
I've just made this clear in 
https://en.wikipedia.org/wiki/Certificate_signing_request and pointed out there 
the main limitation of the PKCS #10 format.

I'll continue my reading with your pointers, thanks :)

Happy reading on CRMF and alternative forms of PoP [:-)]
Yet the novelties in the upcoming RFCs that I also mentioned do not include new 
contents regarding PoP.

Regards,
David
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