Subject: Re: [OAUTH-WG] [DPoP] Protected resource access and invalid DPoP proofs

From: Dmitry Telegin <[email-masked]>
Date: Fri, 24 Sep 2021 06:00:18 +0300

Hi Brian,

Just wondering if there's still a chance for this to be addressed in 04? I
could try preparing a draft PR if that helps.

On a related note, are there any recommendations on the contents of the
"error_description" WWW-Authenticate attribute? For example, our prototype
DPoP implementation for Keycloak recognizes the following error conditions:
- DPoP proof decoding failure
- Invalid DPoP signature
- Invalid or missing "typ" in DPoP header
- Unsupported DPoP algorithm
- No JWK in DPoP header
- No public key in DPoP header
- Private key is present in DPoP header
- DPoP mandatory claims are missing
- DPoP HTTP method/URL mismatch
- Malformed HTTP URL in DPoP proof
- DPoP proof has already been used
- DPoP proof is not active
- No access token hash in DPoP proof (when used with an access token)
- DPoP proof access token hash mismatch (same)

Would you recommend to a) provide detailed info (above) in
error_description, b) provide generic "DPoP proof missing or invalid", c)
omit error_description?

Thanks,
Dmitry

On Tue, Aug 10, 2021 at 12:58 AM Brian Campbell <bcampbell=
[email-masked]> wrote:

> Hi Dmitry,
>
> I think you are right that it's probably worthwhile to allow for a
> distinction in a protected resource error response. I'm inclined to say
> that a new error code such as "invalid_dpop_proof" to use with the 401
> response containing the DPoP WWW-Authenticate header is the most
> straightforward way to accommodate it in the document. I'll look to add
> that, probably somewhere in section 7
> <https://www.ietf.org/archive/id/draft-ietf-oauth-dpop-03.html#name-protected-resource-access>,
> in the next draft revision.
>
>
> On Thu, Aug 5, 2021 at 8:50 AM Dmitry Telegin <dmitryt=
> [email-masked]> wrote:
>
>> Hello,
>>
>> When a protected resource is accessed using DPoP proof + DPoP-bound
>> access token, either of those could be invalid. Should we make distinction
>> between these two cases? I.e. should the response always be a 401
>> Unauthorized with WWW-Authenticate: DPoP ... error="invalid_token"? or
>> could we use error="invalid_dpop_proof", similar to token request? or maybe
>> even 400 Bad Request?
>>
>> Regards,
>> Dmitry
>>
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