[Openid-specs-heart] HEART Profiles - Authorization Server OAuth / UMA Clarification

[Eve Maler]

Below:


*Eve Maler*ForgeRock Office of the CTO | VP Innovation & Emerging Technology
Cell +1 425.345.6756 | Skype: xmlgrrl | Twitter: @xmlgrrl
Join our ForgeRock.org OpenUMA <http://forgerock.org/openuma/> community!

On Tue, Dec 8, 2015 at 12:16 PM, Justin Richer <jricher at mit.edu> wrote:

> We’ve discussed the redundancy of the AAT in the UMA working group, and
> we’re mandating claims gathering flows that identify and bind the RqP.
> Since we can’t cut out the AAT entirely and still remain compatible with
> UMA 1.0, this was a workaround. We also did discuss this exact workaround
> on the UMA list and/or tracker: using client_credentials to get the AAT.
>

I'm sorry, but much as you may wish the AAT were gone in UMA V1.0, we are
profiling UMA V1.0. Your opinion may be shared by others, but the UMA WG
has in fact tabled <https://github.com/KantaraInitiative/wg-uma/issues/154>
the issue for the moment, and despite your well-known very strong
preferences, there is simply no official conclusion about what we might
call the "distastefulness" of the AAT.

Although the UMA V1.0.1 patch release signaled future-version directions in
a few very clear-cut, very minor cases, we did not do this with the AAT
issue because it's too massive, potentially backwards-incompatible, and
controversial. And in the meantime, the trust elevation materials I alluded
to in my message actually contribute new thinking to how a solution might
look. There is danger in moving too quickly to preconceived solutions until
we fully understand the problem space.


> I strongly believe that the requirement of a user-delegated AAT
> drastically restricts the deployability of this spec. It requires that the
> RqP have the ability to generate delegated OAuth access tokens from the AS,
> which is controlled by the RO. This simply cannot be counted on unless
> you’re in a very narrow ecosystem, and we cannot assume such an ecosystem
> as a requirement here. This recommendation keeps the syntactic
> compatibility with UMA 1.0 while making the actual protocol more sensible
> and widely deployable.
>
> Ultimately this is a recommendation in an implementer’s draft. If people
> don’t do it, then we change the recommendation.
>

I know what you strongly believe; you've made it clear. :-) For purposes of
our profile, have you given any thought to my suggested workaround -- or
even put thought into other workarounds until future UMA solutions might
come to the fore? My analysis of trust elevation for different ecosystems
<https://github.com/KantaraInitiative/wg-uma/wiki/UMA-Legal:-Business-Models>
seems to suggest that it's not just "very narrow" ecosystems that are
comfortable with an AAT. "Medium" ecosystems, such as with partners, can
also operate fine in this circumstance.  The "widest" type of ecosystem
does have a challenge; this is where my colleague James Philpotts together
with Mike Schwartz have been putting in some fresh thinking.

If we look at identity ecosystems by comparison, most of them live in
"narrow" and "medium" land. "Wide" is always the hardest (though I agree
with your work done at IIW
<http://iiw.idcommons.net/Burning_Bridges_and_Breaking_Brokers> in
describing the emerging technologies as dissolving the frictions that hold
wide ecosystems back), and tends to follow last.

(*N.B.:* I do not want to solve/"litigate" the AAT challenge fully here!
I'm just trying to establish that UMA1.0 constraints should not be solved
with broken recommendations in UMA1.0 profiles.)

Put plainly, I believe that to leave this recommendation in is not a fair
or proper editorial action. The text was inserted on day T minus 6 (so to
speak) after the group began its final review, did not receive a full
discussion using terms widely understood by the full group, is based on an
inaccurate reading of the spec, and reflects a highly personal view of what
the UMA version we're actually profiling "should be" versus what it is. We
have other options; I believe we should explore them.


>
> I do not agree with the call to hold off on the ballot for this issue.
>
>  — Justin
>
> On Dec 8, 2015, at 2:53 PM, Eve Maler <eve.maler at forgerock.com> wrote:
>
> I apologize for only sending this now. The following sentence was not in
> the version on which I sent comments to Justin and Sarah on November 23.
>
> *HEART UMA Sec 2
> <http://openid.bitbucket.org/HEART/openid-heart-uma.html#Tokens>: "It is
> RECOMMENDED that the PAT use a user-delegated mechanism for issuance and
> the AAT use a non-delegated method for issuance."*
>
> I believe this incorrectly specifies a critical profile detail, as well as
> using terms that are not very well-defined.
>
> *Minor issue in the HEART UMA profile and tackling the terminology issue
> for techies and nontechies alike*
>
> First, the minor issue: As we discussed briefly on the call yesterday,
> "user-delegated" and "non-delegated" appear to correspond to what have been
> colloquially called "three-legged" and "two-legged" in the OAuth community.
>
> In plain English, the first one means that a human delegates to a client
> application the right to access some protected resource. The second one
> means that the client gains access to the protected resource autonomously,
> on its own recognizance. (UMA would look at the larger context of the "NPE"
> that the app represents -- in other words, it would note that there
> actually *is* a resource owner and it's not a human being.)
>
> It would be much clearer to identify the acceptable OAuth "grant
> <http://tools.ietf.org/html/rfc6749#section-4>" flows in each case;
> "non-delegated" translates uniquely to the OAuth client credentials
> <http://tools.ietf.org/html/rfc6749#section-4> grant flow.
>
> *Major issue in the HEART UMA profile*
>
> Now the major issue: The "non-delegated" [client credentials]
> recommendation suggested here for the AAT would be incorrect for solving
> any use case where the requesting party is a human being ("natural
> person"). I believe you're suggesting an experimental usage of UMA that
> was not intended by the original spec:
>
> *UMA Core Sec 1.3.2:
> <https://docs.kantarainitiative.org/uma/draft-uma-core-v1_0_1.html#authorization-api>
> "An AAT binds a requesting party, a client being used by that party, and an
> authorization server that protects resources this client is seeking access
> to on this requesting party's behalf. .... The issuance of an AAT
> represents the approval of this requesting party for this client to engage
> with this authorization server to supply claims, ask for authorization, and
> perform any other tasks needed for obtaining authorization for access to
> resources at all resource servers that use this authorization server.**"*
>
> I'm concerned that an implementation that treats the client as
> autonomous/NPE for AAT purposes, and then switches to a "human requesting
> party" interpretation later on during trust elevation, may have anomalous
> behavior when it comes to overall management of the requesting party's
> identity compared to properly conforming authorization servers. This is
> essentially, then, an anti-interoperability recommendation.
>
> Thus, I don't believe we can leave the recommendation as is.
>
> *Side issue probably not for the profile but for UMA generally*
>
> As an aside, it should be noted that, even though the requesting party
> should be the "same entity" referred to in both the AAT stage and later on,
> the authorization server still shouldn't use the AAT to "mine" the identity
> of the requesting party for trust elevation at the later stage. This is a
> temptation we discovered some integrators may fall prey to, which leads to
> a potential privacy violation.
>
> I've been meaning to add a note about this to the UMA Implementer's Guide
> <http://kantarainitiative.org/confluence/display/uma/UMA+Implementer%27s+Guide?src=contextnavchildmode>;
> I'll leave the longer explanation about this for another time (or the UIG
> itself).
>
> *Acknowledgment of the larger UMA issue and suggestions for potential
> profile fixes/additions*
>
> The constraint where the requesting party needs a "login account" of some
> sort at the authorization server used by the resource owner -- let's call
> it "the resource owner's authorization server" (RO's AS), vs. "the
> requesting party's desired authorization server" (RqP's AS), that is, the
> authorization server the requesting party *uses for preference* when
> they're in the resource owner role themselves -- is indeed a tricky one.
>
> (In case people are wondering where the motivation for this requirement
> came from, the passage quoted above describes a key one having to do with
> experience: *UMA Core Sec 1.3.2:
> <https://docs.kantarainitiative.org/uma/draft-uma-core-v1_0_1.html#authorization-api> "... **The
> authorization server is able to use this association to manage future
> processes of authorization and claims-caching efficiently for this
> client/requesting party pair across all resource servers they try to
> access; however, these management processes are outside the scope of this
> specification." *We shall see whether this was the right optimization
> choice at this stage of UMA's life cycle... :-) )
>
> One perhaps semi-satisfying workaround for the purposes of our profile
> might be to recommend that the authorization server offer the requesting
> party the opportunity to single sign-on into the RO's AS using their "RqP's
> AS" login (if they have one). One could imagine an identity trust framework
> among authorization servers so that they're relying parties/identity
> providers to each other in a "star of trust".
>
> *A thought about interactions between the basic profile and higher-order
> profiling for trust elevation*
>
> At ForgeRock we have recently prepared some materials that describe ways
> to do identity-claims-based trust elevation given different widths of UMA
> "ecosystem", once the AAT layer has been laid down. I'd be happy to share
> these materials as food for thought.
>
> Note: They may have some interactions with the basic HEART UMA profile if
> we get into recommending any particular federated identity patterns at this
> basic level, so let me know if you think I should add those materials to
> *this* thread.
>
> *Suggestion for handling the unfortunate Implementer's Draft timing*
>
> I realize that what I'm talking about here is not really a non-normative
> change to the wording. However, if I'm looking at the commits correctly, it
> appears that this change was made as part of a flurry of edits on December
> 1, which is fairly late in the game for a substantive revision (I myself
> was in the wilds of Norway and unfortunately not keeping up with regular
> work very well!). Looking at the list traffic, I'm unclear what requests
> actually led to this change.
>
> I think it would be appropriate to hold off on the ballot, if possible,
> until we discuss what to do with this text. If things are already in the
> works (Debbie?), then I think we may possibly be looking at another
> Implementer's Draft with some alternative (normatively changed) wording. As
> explained to us previously, we can theoretically have as many of these
> drafts as necessary, so we know it's possible, even if not ideal.
>
>
>
>
> *Eve Maler*ForgeRock Office of the CTO | VP Innovation & Emerging
> Technology
> Cell +1 425.345.6756 | Skype: xmlgrrl | Twitter: @xmlgrrl
> Join our ForgeRock.org OpenUMA <http://forgerock.org/openuma/> community!
>
> On Thu, Dec 3, 2015 at 1:38 PM, Justin Richer <jricher at mit.edu> wrote:
>
>>
>> User delegated means an end user delegates access and is involved in the
>> process. Non-delegated means the client is acting on its own behalf for
>> that step. This text is saying the RO needs to set up the relationship
>> between the RS and the AS, but the RqP doesn’t have to be present on the
>> wire to set up the relationship between the client and AS. This is to patch
>> around a technical limitation in UMA 1.0 that would otherwise require the
>> RqP have an account of some type at the AS that was able to generate OAuth
>> tokens.
>>
>>
>>  — Justin
>>
>>
>
>
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