Re: [OAUTH-WG] WGLC Review of PAR

[Brian Campbell <[e-mail]>]

Thanks Justin. Just a couple more responses to responses inline below (but
with lots of content that needs no further discussion removed).

A TL;DR for the WG is that I'd like to get some wider feedback on the
question of changing the one-time-use condition on the request_uri from a
SHOULD to a MUST.

On Tue, Aug 25, 2020 at 4:57 PM Justin Richer <[e-mail]> wrote:

> Hi Brian, just a couple responses inline where it seemed fitting. Thanks
> for going through everything!
>  — Justin
>
> On Aug 25, 2020, at 6:01 PM, Brian Campbell <[e-mail]>
> wrote:
>
> Thanks for the review and comments Justin. Replies (or attempts thereat)
> are inline below.
>
>
> On Wed, Aug 19, 2020 at 2:06 PM Justin Richer <[e-mail]> wrote:
>
>> I’ve done a full read through of the PAR specification, and here are my
>> notes on it.
>>
>>
>>>     ¶2: Of necessity, this spec mixes parameters in the authorization
>>> endpoint and token endpoint registries into a single request. Is there any
>>> danger of conflict between them? The registry holds them in one list but
>>> they could possibly have different semantics in both places.
>>>
>>
>> I think that technically such danger does exist but that it's highly
>> unlikely in practice. Especially because the only token endpoint parameters
>> that are relevant to PAR are those that deal with client authentication
>> (currently client_secret, client_assertion, and client_assertion_type). I'm
>> also not sure what can reasonably be done about it given the way the
>> registries are. I guess PAR could update the registration for those three
>> (client_secret, client_assertion, and client_assertion_type) to also
>> indicate authorization request as a usage location with some commentary
>> that it's only for avoiding name collisions. And offer some guidance about
>> doing the same for any future client auth methods being defined. But
>> honestly I'm not sure what, if anything, to do here?
>>
>> And yes it is super unfortunate that client auth and protocol parameters
>> got mixed together in the HTTP body. I didn't cause that situation but I've
>> certainly contributed to it and for that I apologize.
>>
>
> I think the only perfect solution is to go back in time and fix the
> registries with based on the last decade of knowledge in using them. :P
>
> For this, I think maybe being very prescriptive about the fact that the
> only parameters from the token endpoint that are allowed here are those
> used for client authentication and that when they show up, they’re
> interpreted as in the token endpoint request not the authorization endpoint
> request. Does that work?
>

I think so, yes. And will work on incorporating some text towards that end.




>     I don’t see why a request URI with unguessable values isn’t a MUST for
>> one-time-use, is there a reason?
>>
>
> The reason AFAIK was to not be overly prescriptive and allow for
> eventually consistent or not atomic storage of the data by not strictly
> requiring the AS to enforce one-time-use. Do you think that's too loose or
> could be worded/explained differently or better?
>
>
> I do think it’s too loose and it should be a MUST, and the methods for
> enforcing that “MUST” are going to vary based on the deployments and
> implementations out there.
>
>
I'd be okay with making it a MUST but think maybe it'd be good to hear from
a few more people in the WG before committing to that change.

Can I ask some folks to weigh in on this one? I'm leaning towards making
the change barring objections.

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