[Openid-specs-ab] Key-binding and dpop scope

[Kosuke Koiwai]

That is true Dick.
However, diverting from standards poses some risks of patents and
maintenance costs. I would like to know if anyone in the field shares the
problems.

Kosuke

2025年8月30日(土) 22:17 Dick Hardt <dick.hardt at gmail.com>:

> You can do whatever you want in your application Kosuke!
>
> A standardized spec enables software written by different parties to
> interoperate. From my recollection, your use case is a single party. You
> can ignore the authentication request part if you want. You won't have
> quite the same security characteristics if the client does not
> include dpop_jkt as a parameter.
>
> On Sat, Aug 30, 2025 at 2:09 PM Kosuke Koiwai <kkoiwai at gmail.com> wrote:
>
>> Can we separate the spec to add cnf to id_token and how to ask for it?
>>
>> As I asked before, I want to add the key info to id_token, and the key is
>> the same as the one used for attestation-based client auth.
>>
>> https://lists.openid.net/pipermail/openid-specs-ab/2025-August/010892.html
>>
>> I want to add the cnf claim at the discretion of IdP, so RP doesn’t have
>> to add any to the scope.
>>
>> Kosuke
>>
>>
>> On Sat, Aug 30, 2025 at 19:07 Dick Hardt via Openid-specs-ab <
>> openid-specs-ab at lists.openid.net> wrote:
>>
>>> "bound_key" is crisper and says what is wanted in the token rather than
>>> what is to be done
>>>
>>> On Fri, Aug 29, 2025 at 6:51 PM Dag Helge Østerhagen via Openid-specs-ab
>>> <openid-specs-ab at lists.openid.net> wrote:
>>>
>>>> +1 for both "key_binding" and "cnf". Sigh.
>>>>
>>>> /dag
>>>> ------------------------------
>>>> *From:* Dick Hardt <dick.hardt at gmail.com>
>>>> *Sent:* Friday, August 29, 2025 7:47:45 PM
>>>> *To:* Artifact Binding/Connect Working Group <
>>>> openid-specs-ab at lists.openid.net>
>>>> *Cc:* Dag Helge Østerhagen <dag at udelt.no>; george at practicalidentity.com
>>>> <george at practicalidentity.com>; Filip Skokan <panva.ip at gmail.com>
>>>> *Subject:* Re: [Openid-specs-ab] Key-binding and dpop scope
>>>>
>>>> `key_binding` as scope name?
>>>>
>>>> On Fri, Aug 29, 2025 at 6:35 PM Dag Helge Østerhagen via
>>>> Openid-specs-ab <openid-specs-ab at lists.openid.net> wrote:
>>>>
>>>> Well,  currently the dpop header is used to signal token binding (and
>>>> inclusion of the cnf claim) for access and refresh tokens.   I don't see
>>>> any other use cases in the (near) future.
>>>>
>>>> /dag
>>>> ------------------------------
>>>> *From:* george at practicalidentity.com <george at practicalidentity.com>
>>>> *Sent:* Friday, August 29, 2025 7:01:54 PM
>>>> *To:* Artifact Binding/Connect Working Group <
>>>> openid-specs-ab at lists.openid.net>
>>>> *Cc:* Dag Helge Østerhagen <dag at udelt.no>
>>>> *Subject:* Re: [Openid-specs-ab] Key-binding and dpop scope
>>>>
>>>> My thought is that might depend on whether the ‘cnf’ scope is only
>>>> applied to the id_token or whether cnf claims should be added to other
>>>> issued tokens as well. Currently the proposed key-binding spec is specific
>>>> to id_tokens.
>>>>
>>>> George Fletcher
>>>> Identity Standards Architect
>>>> Practical Identity LLC
>>>>
>>>>
>>>>
>>>> On Aug 29, 2025, at 12:56 PM, Dag Helge Østerhagen via Openid-specs-ab <
>>>> openid-specs-ab at lists.openid.net> wrote:
>>>>
>>>> I like «id_token_cnf», but wouldn’t just «cnf» be more aligned with
>>>> other oidc scopes?
>>>>
>>>> /dag
>>>> ------------------------------
>>>> *From:* Openid-specs-ab <openid-specs-ab-bounces at lists.openid.net> on
>>>> behalf of george--- via Openid-specs-ab <
>>>> openid-specs-ab at lists.openid.net>
>>>> *Sent:* Friday, August 29, 2025 6:14:16 PM
>>>> *To:* Dick Hardt <dick.hardt at hello.coop>
>>>> *Cc:* george at practicalidentity.com <george at practicalidentity.com>;
>>>> Artifact Binding/Connect Working Group <
>>>> openid-specs-ab at lists.openid.net>
>>>> *Subject:* Re: [Openid-specs-ab] Key-binding and dpop scope
>>>>
>>>> That makes sense to me; including ‘cnf’ in the scope name. Would we
>>>> ever want to allow the “key binding” mechanism to use something other than
>>>> DPoP? If so, and the express purpose is to provide key binding for the
>>>> id_token, then I’d recommend something like ‘id_token_cnf’.  It’s specific,
>>>> clear and doesn’t preclude methods other than DPoP to provide the necessary
>>>> data for the cnf claim.
>>>>
>>>> George Fletcher
>>>> Identity Standards Architect
>>>> Practical Identity LLC
>>>>
>>>>
>>>>
>>>> On Aug 29, 2025, at 11:00 AM, Dick Hardt <dick.hardt at hello.coop> wrote:
>>>>
>>>> I have no strong views on the scope name. Open to other ideas /
>>>> suggestions / opinions!
>>>>
>>>> Perhaps `cnf` to align with the claim?
>>>> ᐧ
>>>>
>>>> On Fri, Aug 29, 2025 at 3:57 PM <george at practicalidentity.com> wrote:
>>>>
>>>> Hi,
>>>>
>>>> Would it make sense to change the scope name identified in the
>>>> key-binding spec from something specific like ‘dpop’ to something more
>>>> generic? e.g. ‘id_token_kb’ ? Or maybe just make clearer that the RP is
>>>> looking for key bound tokens? e.g. ‘dpop_kb’? I just worry that ‘dpop’ by
>>>> itself does not communicate the intended behavior.
>>>>
>>>> Thoughts?
>>>>
>>>> George Fletcher
>>>> Identity Standards Architect
>>>> Practical Identity LLC
>>>>
>>>>
>>>>
>>>>
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