client_metadata section (text & references)

[c2bo]

Client Metadata is first introduced in Section 5 without referencing the section where it is/should be defined (Section 9). jwks and jwks_uri are also used without mentioning that section.

client_metadata is mentioned the first time with this text:

Depending on the Client Identifier Scheme, the Verifier can communicate a JSON object with its metadata using the client_metadata parameter which contains name/value pairs defined in Section 4.3 and Section 2.1 of the OpenID Connect Dynamic Client Registration 1.0 [OpenID.Registration] specification as well as [RFC7591].

which is a lot more detailed than the text for client_metadata in section 9:

To convey Verifier metadata, Client metadata defined in Section 2 of [RFC7591] is used.

I would propose to extend the text in section 9 and reference it when client_metadata is introduced in Section 5. It might also make sense to explicitly mention jwks and jwks_uri in section 9 next to vp_token (it is mentioned via the reference, but this would make implementers life probably easier).

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original comment:

When reading the text I started wondering if our references for client_metadata need a bit of work though: jwks and jwks_uri is used throughout the text but does not reference section 9 where client_metadata is formally introduced with the reference to DCR. I think we should reference section 9 at least once (which is only referenced for vp_token right now). I guess that should be a separate issue/PR?

Originally posted by @c2bo in https://github.com/openid/OpenID4VP/pull/242#pullrequestreview-2279242569