Server metadata needs to specify supported proof types / algorithms

[Richard Barnes]

The credential request contains a proof of possession of a private key by the client. The spec allows flexibility in the type of proof provided, though only JWT is defined. (I filed #1696 on whether this flexibility is required.) A client needs to know what proof types and signature algorithms the server supports. It seems like this calls for some server metadata fields, say credential_proof_types_supported and credential_request_alg_values_supported.

[Michael Jones]

We looked at this on the 31-Oct-22 working group call. It would probably benefit from discussion on a SIOP special topic call.

[Kristina Yasuda]

I agree an Credential Issuer metadata need proof_type_supported

equivalent of credential_request_alg_values_supported is already covered by cryptographic_binding_methods_supported and cryptographic_suites_supported defined here: https://openid.bitbucket.io/connect/openid-4-verifiable-credential-issuance-1_0.html#section-10.2.3.1-2.3.1

[Kristina Yasuda]

PR #452

[Kristina Yasuda]

PR merged