Re: [OAUTH-WG] Call for Adoption

Nat Sakimura <sakimura@gmail.com> Thu, 21 January 2016 14:23 UTC

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From: Nat Sakimura <sakimura@gmail.com>
Date: Thu, 21 Jan 2016 14:23:38 +0000
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To: Justin Richer <jricher@mit.edu>, Mike Jones <Michael.Jones@microsoft.com>
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Subject: Re: [OAUTH-WG] Call for Adoption
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Mike,

You just criticize my draft. That's ok, but I would really like to get some
response to my questions stated in
https://www.ietf.org/mail-archive/web/oauth/current/msg15483.html . To me,
it just does not seem to work, and the combination of the oauth-meta and
PKCE seems to be much more elegan, nicer, and much simpler to implement. If
you just give up the dynamic response at the authorization endpoint, then
you even do not have to touch the code but just change a config file.

Please convince me by answering to my questions.

For the record of Yokohama, I do not recall much about duplication in OAuth
session. The poll in the room was 19 for / zero against / 4 persons need
more information. Indeed, it is not duplicating much. And if you move to a
new model without pre-configured discovery, it is not duplicating any but
the resource endpoint URI, which is optional and is for the cases where the
client did not know the concrete resource endpoint to start with.

I understand your usecases always start from a concrete endpoint location.
Mine do not. In a four party model, it is likely not. The user just want to
have the service to fetch his data from some resource endpoint. He just
hits the service. He does not hit the resource endpoint directly. For
example, in the case of a consumer using a personal finance platform
(PFP)to manage his pension fund, he hits the PFP and not the Pension fund.
Assuming that the pension fund has delegated the authorization control to
the authorization server, then, the authorization server should return both
the access token and the endpoint of the pension fund so that the PFP can
pull the data using them. A similar model holds for personal health service
and health care providers.

Best,

Nat


2016年1月21日(木) 21:18 Justin Richer <jricher@mit.edu>;:

> Convergence is exactly what I’m arguing for, though. These things ought to
> work together.
>
>  — Justin
>
> On Jan 21, 2016, at 2:55 AM, Mike Jones <Michael.Jones@microsoft.com>;
> wrote:
>
> My memory of the discussions of the oauth-meta draft in Yokohama were that
> many people felt that it was unnecessarily dynamically duplicating a lot of
> information that the client already had.  Most of us that were aware of the
> attacks then were in favor of a more targeted, minimal approach.  You were
> listened to in Yokohama, but that didn’t necessarily mean that people
> agreed with the approach.  Participants were already aware of the
> oauth-meta proposal in Darmstadt but no one spoke up in favor of it that I
> can recall.  Rather, I think people were thinking that “less is more”.
>
>
>
> There have also been discussions in the last day about how dynamically
> returning a resource URL, which oauth-meta does, is both unnecessary (since
> the client initiated the resource authorization already knowing what
> resource it wants to access) and often problematic, since many
> authorization servers can authorize access to multiple resources.  If
> anything, the client should be telling the authorization server what
> resource it wants to access – not the other way around.
>
>
>
> I’m not saying that there aren’t some good ideas in the oauth-meta draft –
> I’m sure there are, just as there are in the approach designed by the
> participants in Darmstadt.  While I volunteered to write the first draft of
> the mix-up-mitigation approach, it really reflects something a lot of
> people have already bought into – as evidenced in the passion in the
> high-volume “Mix-Up About The Mix-Up Mitigation” thread, and not just my
> personal project.
>
>
>
> If you think there are things missing or wrong in the mix-up-mitigation
> draft, please say what they are.  That will help us quickly converge on a
> solution that will work for everyone.
>
>
>
>                                                           Sincerely,
>
>                                                           -- Mike
>
>
>
> *From:* Nat Sakimura [mailto:sakimura@gmail.com <sakimura@gmail.com>]
> *Sent:* Wednesday, January 20, 2016 11:17 PM
> *To:* Mike Jones <Michael.Jones@microsoft.com>;; William Denniss <
> wdenniss@google.com>;; Justin Richer <jricher@mit.edu>;
> *Cc:* oauth@ietf.org
> *Subject:* Re: [OAUTH-WG] Call for Adoption
>
>
>
> Hi Mike.
>
>
>
> Conversely, I would like to ask why this approach does not work for Mix-up
> attack. As Nov stated, we in fact have discussed the approach in quite a
> length back in Yokohama. I really would like to know why it does not work.
>
>
>
> Besides, for oauth-meta approach, mix-up attack is only one of the thing
> it solves.
>
>
>
> Nat Sakimura
>
>
>
> 2016年1月21日(木) 16:02 Mike Jones <Michael.Jones@microsoft.com>;:
>
> Not to be negative, but I disagree with adopting
> draft-sakimura-oauth-meta.  We should define and promote one mitigation
> approach to the mix-up attacks.  Having two would confuse implementers and
> cause compatibility problems – reducing overall security.
>
>
>
> The approach defined in draft-jones-oauth-mix-up-mitigation was created in
> collaboration with the security researchers who identified the problems in
> the first place, was vigorously discussed in the security meeting Hannes
> and Torsten held in Darmstadt, and has been since refined based on
> substantial input from the working group.  And at least three implementers
> have already stated that they’ve implemented it.  I’m not saying that it’s,
> but if there are things missing or things that need to be improved in our
> approach, we should do it there, rather introducing a competing approach.
>
>
>
> Also, standard OAuth deployments register the client and then use the
> information gathered at registration time for subsequent protocol
> interactions.  They do not need all the configuration information for the
> authorization server to be retransmitted at runtime.  The oauth-meta draft
> goes too far in that direction, at least as I see it.  Returning things two
> ways creates its own problems, as discussed in the Duplicate Information
> Attacks security considerations section (7.2) of the mix-up-mitigation
> draft.
>
>
>
> I’ll note that the mix-up-mitigation approach is compatible with existing
> practice in both static and dynamic metadata discovery.  Replying to
> Justin’s comment that “It's the pre-configured discovery document that's
> at the root of the mix-up attack in the first place” – this is not the
> case.  The attacks can be performed without either discovery or dynamic
> registration.
>
>
>
> I would be interested in hearing a technical discussion on whether there
> are aspects of the oauth-meta approach that mitigate aspects of the attacks
> that the mix-up-mitigation approach does not.  That could help inform
> whether there are additional things we should add to or change in the
> mix-up draft.
>
>
>
>                                                           -- Mike
>
>
>
> *From:* OAuth [mailto:oauth-bounces@ietf.org] *On Behalf Of *William
> Denniss
> *Sent:* Wednesday, January 20, 2016 10:37 PM
> *To:* Justin Richer <jricher@mit.edu>;
> *Cc:* oauth@ietf.org
> *Subject:* Re: [OAUTH-WG] Call for Adoption
>
>
>
> +1 to adopt this, and I agree with Justin's comments.
>
>
>
> On Wed, Jan 20, 2016 at 9:53 PM, Justin Richer <jricher@mit.edu>; wrote:
>
> +1
>
> Inline discovery and pre-configured discovery (ie, .well-known) should at
> the very least be compatible and developed together. It's the
> pre-configured discovery document that's at the root of the mix-up attack
> in the first place.
>
>  -- Justin
>
>
>
> On 1/19/2016 10:30 PM, Nat Sakimura wrote:
>
> Just to give more context, at IETF 94, I have done a presentation on
> discovery.
>
>
>
> According to the minutes,
>
>
>
>     (f) Discovery (Nat)
>
>
>
>              Nat explains his document as an example of the work that has to be done
>
>              in the area of discovery, which is a topic that has been identified
>
>              as necessary for interoperability since many years but so far there
>
>              was not time to work on it. Mike, John and Nat are working on a new
>
>              document that describes additional discovery-relevant components.
>
>
>
>              Poll: 19 for / zero against / 4 persons need more information.
>
>
>
> The document discussed there was
> https://tools.ietf.org/html/draft-sakimura-oauth-meta-05. This is a
> simple (only 1-page!) but a very powerful document that nudges towards
> HATEOAS which is at the core of RESTful-ness. It also mitigates the Mix-up
> attack without introducing the concept of issuer which is not in RFC6749.
> It is also good for selecting different endpoints depending on the user
> authentication and authorization results and more privacy sensitive than
> pre-announced Discovery document. It also allows you to find to which
> protected resource endpoint you can use the access token against.
>
>
>
> In the last sentence of the minutes, it talks about "a new document that
> describes additional discovery-relevant components". This is
> https://tools.ietf.org/html/draft-jones-oauth-discovery-00.  It went for
> the call for adoption. However, it is only a half of the story. I believe
> https://tools.ietf.org/html/draft-sakimura-oauth-meta-05 that was
> discussed at IETF 94 and had support there should be adopted as well.
>
>
>
> Nat Sakimura
>
>
>
>
>
>
>
>
>
> 2016年1月20日(水) 12:05 Nat Sakimura <sakimura@gmail.com>;:
>
> Thanks Hannes.
>
>
>
> I did not find https://tools.ietf.org/html/draft-sakimura-oauth-meta-05, which
> was discussed in Yokohama, and was largely in agreement if my recollection
> is correct. Why is it not in the call for adoption?
>
>
>
>
>
>
>
> 2016年1月19日(火) 20:39 Hannes Tschofenig <hannes.tschofenig@gmx.net>;:
>
> Hi all,
>
> we have submitted our new charter to the IESG (see
> http://www.ietf.org/mail-archive/web/oauth/current/msg15379.html) and
> since some IESG members like to see an updated list of milestones as
> well. For this reason, based on a suggestion from Barry, we are also
> starting a call for adoption concurrently with the review of the charter
> text by the IESG.
>
> We will post separate mails on the individual documents. Your feedback
> is important! Please take the time to look at the documents and provide
> your feedback.
>
> Ciao
> Hannes & Derek
>
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