Hi, Michael.

On Fri, 3 Oct 2025 at 18:28, Michael Richardson <[email protected]> wrote:
> Thomas Fossati <[email protected]> wrote:
>     > We want to transport DICE [0] certificate chains in CMWs [1], and for
>     > that, we need a media type.
>
>     > Note that DICE certificate chains differ semantically from standard
>     > X.509 certificate chains in that they also represent attestation
>     > Evidence [2].  Therefore, using
>     > * application/pkcs7-mime; smime-type="certs-only"
>     > * application/cose-x509; usage=chain, and
>     > * application/pkix-pkipath
>     > would provide too coarse typing information, so we'd like to improve 
> this.
>
>     > One way would be to extend the application/cose-x509 "usage" parameter
>     > to include the value "dice-chain", i.e., application/cose-x509;
>     > usage=dice-chain.
>
> cose-x509.  I was thinking this is from cbor-encoded-cert, but it defines 
> cose-c509-cert.
> And that definition has usage=chain, so was this a typo?  NOPE.
> cose-x509 is RFC9360... and COSE_X509 is a CBOR sequence of bstr wrapped
> DER-encoded PKIX certificates.
> I think that this means that there is CBOR definite(?) array of bytes.
>
> So this becomes a dice-chain.
> And after you do CoAP/Content-Format registration, you get an integer for the
> CBOR CMW, so any verbosity of the media type is a moot point.
>
>     > Would that be acceptable?  If so, what steps need to be taken to
>     > register the new parameter value?
>     > Do we need a specification, and if so, what kind? Or is a request to
>     > the media-types list sufficient?
>
> I understand that an email to [email protected] with the template is
> enough.  However, I find that one has to poke the reviewers.
> I'm hoping IANA's new DE RT system will get help..

OK, thanks for the tip; I'll forward the request to [email protected] then.

cheers, t

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