[Openid-specs-ab] JWT Header for signed id tokens

[george at practicalidentity.com]

Hi Joseph,

I agree. My point was more that OP Commands should NOT try and relate itself to id_tokens at all. Instead, define the OP Command JWT using current best practice and then make the point that the keys used to sign the OP Command are the same as those used to sign an ID Token. Otherwise, I’m not sure there need to be any mention of ID Tokens at in the context of OP Commands.

George Fletcher
Identity Standards Architect
Practical Identity LLC



> On Mar 13, 2025, at 8:46 PM, Joseph Heenan <joseph at authlete.com> wrote:
> 
> Hi George
> 
> As others said, the OP Commands is required to be explicitly typed, at least in the current draft.
> 
> However explicitly typing the OP Command is not sufficient to avoid confusion attacks with an id_token, as checking typ is not part of the id_token processing rules in Connect Core.
> 
> Thanks
> 
> Joseph
> 
> 
>> On 14 Mar 2025, at 01:57, george--- via Openid-specs-ab <openid-specs-ab at lists.openid.net> wrote:
>> 
>> Hi,
>> 
>> As part of OP Commands, a design goal is to re-use the signing mechanisms of the id_tokens in the ecosystem (at least that is my understanding). In looking at the OpenID Connect core spec, it’s not very clear what should be present in the JWT Header object of a signed (JWS) id_token. The examples in the appendix include the ‘kid’ and ‘alg’ claims. 
>> 
>> I’m wondering if it’s possible for the OP Command to be an explicitly typed JWT to make it very clear it is NOT an id_token (rather than relying on presence or absence of a nonce claim) and still use the same keys for signing. It seems to me that the keys used for signing are not in any way bound to only being used for id_tokens and hence could be used for other JWT based structures.
>> 
>> That might make some of this simpler and allow OP Commands to be extended in a cleaner way than trying to maintain some compatibility to id_tokens.
>> 
>> Thoughts?
>> 
>> George Fletcher
>> Identity Standards Architect
>> Practical Identity LLC
>> 
>> 
>> 
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>