Improve metadata for vp formats

[David W Chadwick]

The current specification only has one parameter “vp_formats” which is meant to specify the formats for both VCs and VPs. Thus four values for both VP and VC formats are specified. Even though the parameter is REQUIRED, nevertheless a RP can omit all VC formats and still be conformant. This is shown in the example for “an RP registering with a Standard OP via dynamic client registration”. Only the values “jwt_vp” and “ldp_vp” are specified for “vp_formats”.

In order to rectify this, it is suggested that the RP has two new meta-data parameters “vp_formats” and “vc_formats” instead of just “vp_formats”. Both should be REQUIRED, and two values of each should be defined (with future ones being possible for both). In this way a conformant RP will have to publish both the VC and VP formats that it supports.

‌

[Kristina Yasuda]

Discussed in 2022-01-06 SIOP call

[Michael Jones]

These metadata values shouldn’t be required since VC and VP support is not required.

[David W Chadwick]

As a minimum additional clarification text is required in the current spec, since the current text wrongly implies that VP without VC metadata (or vice versa) can be published, and indeed, the examples do this.

[Kristina Yasuda]

technically, vc-data-model spec allows for a VP without a VC. and some of the credentials (anoncreds, for example) do not have VP-VC structure. I think the best we can do is to clarify that if VP-VC structure is used, metadata should include VC formats in vp_formats (or we can add optional vc_formats too)

[David W Chadwick]

Kristina, you are correct. Therefore I suggest that vc_formats is added as an optional parameter.

[Kristina Yasuda]

Would identifiers in this table in the Issuance and presentation specs solve the problem - will do a PR referencing this table from the SIPO spec

‌

[Kristina Yasuda]

PR #209

[Kristina Yasuda]

will do a PR adding a clarifying text that when VC is requested, RP MUST include a format in which VC is being requested, when it is requested.

[Kristina Yasuda]

PR #235

[Kristina Yasuda]

PR merged