[OAUTH-WG] Re: draft-ietf-oauth-sd-jwt-vc-18 early Httpdir review

[Brian Campbell <[e-mail]>]

Thanks Mark (and AI) for the review. Daniel (and AI) created this PR
https://github.com/oauth-wg/oauth-sd-jwt-vc/pull/422 addressing the
feedback. I (without AI) reviewed it and merged the changes, which will be
in the next (-19) revision of the draft.

On Thu, Aug 13, 2026 at 12:18 AM Mark Nottingham via Datatracker <
[e-mail]> wrote:

> Document: draft-ietf-oauth-sd-jwt-vc
> Title: SD-JWT-based Verifiable Digital Credentials (SD-JWT VC)
> Reviewer: Mark Nottingham
> Review result: Almost Ready
>
> *[Drafted with AI assistance from a structured review run over the
> document and
> the WG's record, then reviewed and edited by me.]*
>
> The draft is reasonable where it touches HTTP. It uses GET throughout,
> puts key
> material behind HTTPS rather than in the DNS, and uses the
> discovery-document-plus-links pattern RFC 9205 recommends. The
> `.well-known`
> construction in Section 3 is correct.
>
> The problem is that it specifies requests but is almost silent about
> responses.
> It defines four fetches -- the `/.well-known/jwt-vc-issuer` document,
> `jwks_uri`, Type Metadata from `vct` and `extends`, and the logo /
> background /
> SVG-template `uri`s -- and gives partial HTTP behaviour for two. Issues 1
> to 5
> all follow from that.
>
> This WG has already done most of the relevant analysis in
> draft-ietf-oauth-client-id-metadata-document: redirects, server-side
> request
> forgery (SSRF) and special-use addresses, HTTPS versus `data:`, cache
> headers.
>
> # Issues
>
> **1. Redirect handling is unspecified**
>
> "redirect" and "3xx" don't appear in the document. RFC 9205 Section 4.6.1
> asks
> applications to say whether redirects are followed, because user agents
> may or
> may not follow them.
>
> Section 6.1 specifies a check performed *before* the request -- "Before
> making
> a request to the JWT VC Issuer Metadata endpoint, the Holder or Verifier
> MUST
> validate the URL...". A 3xx arrives after that check has passed.
>
> The document needs to say (probably globally) whether redirects are
> followed
> and under what constraints, and apply the Section 6.1 validation to each
> URL
> actually connected to, not just the first.
>
> **2. Rendering URIs are underspecified**
>
> The rendering URIs get very little specified HTTP behaviour: no method,
> status,
> media type, size or time bound, no scheme constraint. Is an `http:` logo
> URI
> conformant? Section 4.5.1.2.2 covers references out of the SVG --
> "consuming
> applications MUST ensure that references to external resources (images,
> etc.)
> from within the SVG cannot be used to track users or the usage of
> credentials"
> -- but says nothing about the fetch of the SVG itself. Section 7.4 is
> scoped to
> the Type Metadata document, not the resources it points at.
>
> Restating Section 6.1's requirements once, generally, for every URL the
> specification causes a Consumer to dereference would some of this.
> Constraining
> the rendering URIs to `https:` or `data:` would also help.
>
> **3. Pinning success to 200.**
>
> Sections 3.2 and 4.3.1 both say "A successful response MUST use an HTTP 200
> status code". RFC 9205 Section 3.1 asks applications not to overlay the
> semantics of generic protocol elements.
>
> Instead, describe the semantics -- a representation of the metadata
> resource,
> retrieved with GET -- rather than pinning a status code.
>
> **4. The caching rule is incomplete.**
>
>    Otherwise, the Consumer MUST use the Cache-Control header of the HTTP
>    response to determine how long the metadata can be cached.
>
> Cache-Control isn't the only input to the HTTP caching model. Point at RFC
> 9111
> instead. Also tell publishers to send an explicit freshness lifetime, and
> say
> whether the integrity-keyed indefinite cache overrides origin directives
> such
> as `no-store`.
>
> **5. The integrity mechanism is specified by reference to an algorithm that
> fails cross-origin.**
>
> Section 5 requires a Consumer to "MUST verify the integrity of the
> retrieved
> document as defined in Section 3.3.5 of [W3C.SRI]". Step 3 of that
> algorithm is
> "If response is not eligible for integrity validation, return false", and
> Section 3.3.2 makes eligibility depend on the response being same-origin or
> CORS-permitted. Every URL this document integrity-checks is cross-origin by
> construction, and CORS is never mentioned.
>
> So in a browser-hosted wallet the cited algorithm returns false, Section
> 5's
> MUST fails, and Section 4.7 rejects the credential. In a native consumer
> there's no Fetch response and no loading origin, so step 3 has no meaning
> and
> every implementer will quietly skip it.
>
> If browsers are in scope, this needs an `Access-Control-Allow-Origin`
> requirement on the fetched documents. If not, cite SRI for the syntax of
> the
> integrity-metadata string and specify the digest comparison in your own
> words.
> Note also that the cited section doesn't survive into SRI 2, so the
> reference
> is to a form of the algorithm current SRI no longer contains.
>
> **6. `vc+sd-jwt` is now assigned to someone else.**
>
> Section 2.2.1 says "both vc+sd-jwt and dc+sd-jwt should be accepted as the
> value of the typ header for a reasonable transitional period". Is this
> intended
> to go into the permanent RFC, or will it be removed?
>
> # Comments
>
> - No normative reference to RFC 9110 or RFC 9111, though the document
> specifies
> GET, status codes, a content type and `Cache-Control` behaviour. Same for
> RFC
> 3986, given Section 3's "scheme, host and, optionally, port number and path
> components, but no query or fragment components".
>
> - `jwks_uri` is defined and never specified: no method, status code,
> content
> type, caching or integrity, and Section 6.1 doesn't reach it. If that's
> deliberate deferral to RFC 7517, say so.
>
> - `nosniff` and `Content-Security-Policy` appear nowhere. RFC 9205 Section
> 4.13
> names them as response-side mitigations for the active-content risk
> Sections
> 4.5.1.2.2 and 6.5 address entirely on the client side. Your resources
> remain
> reachable by a browser whether or not that's intended.
>
> - No response message appears anywhere: Figures 12 and 13 are two-line
> requests, Figures 14, 15 and 17 are bare JSON. RFC 9205 Section 4.1 asks
> for
> both request and response with complete header sections. RFC 8414 Section
> 3.2
> and RFC 9728 Section 3.2 both show one, and it's the artefact that would
> have
> surfaced issues 3 and 5.
>
> - Distinct media types for the two metadata documents over
> `application/json`
> would have been nice, per RFC 9205 Section 4.8, but I see this was raised
> in
> issue #388.
>
> - Section 6.1 uses "internal" three times and defines it nowhere.
> draft-ietf-oauth-client-id-metadata-document cites RFC 6890 for the same
> requirement.
>
> # Nits
>
> - Section 1.3 uses the pre-RFC 8174 boilerplate. Note there is a lowercase
> "should" in Section 2.2.1.
>
> Cheers,
>
>
>

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