We have an open issue
<https://github.com/oauth-wg/oauth-identity-assertion-authz-grant/issues/28>
in token exchange with ID Assertion Authorization Grant
<https://datatracker.ietf.org/doc/html/draft-ietf-oauth-identity-assertion-authz-grant>
that was recently adopted to add support for DPOP so this is timely.  We
wanted to flow the key binding from the client's access token to the issued
ID-JAG.  OpenID Connect Key Binding
<https://dickhardt.github.io/openid-key-binding/main.html>was also recently
adopted in OIDF ab-connect WG which would allow for DPOP with ID Token as
the subject token so we would need another param to support this use case.
Your proposal of a new param makes sense and would be great to standardize
so we don't define a different mechanism in ID-JAG.

-Karl

On Mon, Oct 13, 2025 at 12:40 AM Vladimir Dzhuvinov | Connect2id <
[email protected]> wrote:

> The new document clarifying the use of DPoP with device grants is giving
> me hope that we'll agree on a similar DPoP spec for the token exchange.
> Have there been thoughts on this in the WG?
>
> The token exchange specs a *subject_token* and an optional *actor_token*.
> If any of these are DPoP bound, say the *subject_token* is a DPoP access
> token, the client has to include the DPoP + ath proof in the request. The
> DPoP header in token requests (according to RFC 9449) is reserved to enable
> a DPoP binding for the issued token. This means a DPoP header will not work
> for the *subject* / * actor_token*. My preference has been to use a
> dedicated form parameter - *subject_token_dpop* and *actor_token_dpop* for
> this purpose.
>
> Thoughts / comments on this?
>
>
> https://datatracker.ietf.org/doc/html/draft-parecki-oauth-dpop-device-flow
>
> --
> Vladimir Dzhuvinov
>
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