[Openid-specs-ab] OpenID Connect Key Binding vs OpenID Connect UserInfo Verifiable Credentials

[Michael Jones]

Dear Morteza, Richard, Pieter, and Kristina,

I am writing as an OpenID Connect working group chair to ask you what your plans are for the UserInfo VC draft (https://openid.net/specs/openid-connect-userinfo-vc-1_0.html).  The current draft is over 2 years old and is the -00 draft.  Furthermore, I observed that it uses VCDM 1.1, rather than VCDM 2.0 which replaced it.

Is one of you planning to continue working on the draft or should the working group consider it to be inactive?

Part of the context of the question is that Dick Hardt and Ethan Heilman have created the OpenID Connect Key Binding draft (https://github.com/dickhardt/openid-key-binding), which like your draft, uses key binding to an OpenID Connect issued token – but their draft binds the ID Token, rather than the UserInfo response.  The working group is discussing whether to adopt their draft.

We wanted to understand the relationship between your work and their work before potentially issuing a call for adoption.

Thanks for any information you can provide.

                                                                -- Mike

From: Openid-specs-ab <openid-specs-ab-bounces at lists.openid.net> On Behalf Of Brian Campbell via Openid-specs-ab
Sent: Thursday, September 4, 2025 6:15 AM
To: Dick.Hardt at gmail.com; Artifact Binding/Connect Working Group <openid-specs-ab at lists.openid.net>
Cc: Brian Campbell <bcampbell at pingidentity.com>; ethan.r.heilman at gmail.com
Subject: Re: [Openid-specs-ab] OpenID Connect Key Binding vs OpenID Connect UserInfo Verifiable Credentials

I suspect the intent of the homework runs a little deeper. Like perhaps coordinating with the UserInfo Verifiable Credentials authors to see if they are interested in reengaging with the work. Or understanding the rationale for some of the design decisions made - id token vs. userinfo endpoint vs. credential issuance endpoint being one that seems particularly relevant but just one.

On Thu, Aug 21, 2025 at 11:39 AM Dick Hardt via Openid-specs-ab <openid-specs-ab at lists.openid.net<mailto:openid-specs-ab at lists.openid.net>> wrote:
Here is my homework as assigned by the working group chair. :)

KB = OpenID Connect Key Binding
UVC = OpenID Connect UserInfo Verifiable Credentials
Links to specs at bottom

Tl;dr:
KB adds the key to an ID Token
UVC creates a verifiable credential with same info, but VC syntax
KB does it in one call to OP
UVC requires two calls to OP

Key Bound Token
KB outputs an id_token that includes a `cnf` claim of the public key
UVC outputs a verifiable credential with a `did:jwk:ey...` claim
Both include all the same user claims


Authentication Request
- KB uses `dpop` scope as well as `dpop_jkt` parameter
- UVC uses `userinfo_credential`

KB has extra layer of security as `dpop_jkt` provides additional assurance between authentication request and token request

Token Request
- KB - RP passes DPoP JWT as header
- UVC has no changes

Token Response
- KB - OP passes back id_token that includes `cnf` claim
- UVC - OP passes back an access_token as well as c_nonce and c_nonce_expires_in

At this point, KB has completed the key binding ...

Credential Request and Response
UVC continues on
- RP generates a verifiable credential request and passes it with the access_token as a bearer token to the OP's credential endpoint
- OP returns a verifiable credential


https://dickhardt.github.io/openid-key-binding/main.html
https://github.com/dickhardt/openid-key-binding

https://openid.net/specs/openid-connect-userinfo-vc-1_0.html


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