Re: Httpdir telechat review of draft-ietf-oauth-step-up-authn-challenge-13

Thank you for the review Mark. I've replied inline below with some context
or explanation as best I can. And I'll put together a PR with corresponding
changes/clarifications.

On Tue, Apr 4, 2023 at 11:18 PM Mark Nottingham via Datatracker <
noreply@ietf.org> wrote:

> Reviewer: Mark Nottingham
> Review result: Not Ready
>
> # HTTPDIR review of drat-ietf-oauth-step-up-authn-challenge-13
>
> I am an assigned HTTP directorate reviewer for
> draft-ietf-masque-connect-ip.
> These comments were written primarily for the benefit of the ART Area
> Directors. Document editors and shepherd(s) should treat these comments
> just
> like they would treat comments from any other IETF contributors and resolve
> them along with any other Last Call comments that have been received. For
> more
> details on the HTTP Directorate, see
> https://datatracker.ietf.org/group/intdir/about/.
>
> I've entered a 'not ready' position because of the first issue below; the
> remaining are relatively easy to address.
>
> ## Comments
>
> ### Global HTTP Authentication Parameters
>
> This draft seems to modify the HTTP authentication mechanism globally,
> regardless of the scheme in use. For example:
>
> "This specification introduces a new error code value for the error
> parameter
> of [RFC6750] or authentication schemes, such as [I-D.ietf-oauth-dpop],
> which
> use the error parameter"
>
> [...]
>
> "Furthermore, this specification defines additional WWW-Authenticate
> auth-param
> values to convey the authentication requirements back to the client."
>
> [...]
>
> "A client receiving an authorization error from the resource server
> carrying
> the error code insufficient_user_authentication SHOULD parse the
> WWW-Authenticate header for acr_values and max_age and use them, if
> present, in
> constructing an authorization request"
>
> If that is the intent, you need to update RFC9110 (which is likely to be
> contentious); otherwise, you need to scope it in such a way that
> authentication
> schemes 'opt into' their use.
>

The intent is definitely not to globally modify the HTTP authentication
mechanism. Rather the intent is to provide a new error code and two new
parameters for the "Bearer" authentication scheme challenge from RFC6750
(and other OAuth schemes like "DPoP" that use the RFC6750 challenge params).




>
> ### Header Definition
>
> "This document also introduces acr_values and max_age parameters for the
> WWW-Authenticate response header defined by [RFC6750]"
>
> RFC6750 does not define WWW-Authenticate; RFC9110 does.
>

Yeah, that was sloppy language. Apologies. The parameters are introduced
for the Bearer authentication scheme challenge defined by [RFC6750] not the
WWW-Authenticate response header in general.



## Nits
>
> I found the terminology in this draft confused, and confusing. E.g.,
>
> * Use of the term 'resource server' throughout is very jarring -- on the
> Web,
> it's just a 'resource'. The 'server' is responsible for the resource; if
> you
> mean the server, say 'server'; if you mean the resource, say 'resource'.
> Don't
> combine them.
>
> * Likewise, 'resource request' is redundant; every request is for a
> resource.
> Just say 'request'.
>
> * Similarly, the diagram on page 4 shows a 'resource server' returning a
> 'protected resource'. Resources are never transferred over the network;
> they
> send representations in responses -- one of those terms should be used.
>

As Aaron mentioned in his reply to this thread - these terms are defined in
RFC6749 and used throughout the OAuth family of specs providing useful
context and disambiguation for OAuth roles and functionality etc. I agree
with Aaron about adding a terminology paragraph to the draft to make it
more explicit.

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