Re: [GNAP] [Txauth] Revisiting the photo sharing example (a driving use case for the creation of OAuth)

Francis Pouatcha <fpo@adorsys.de> Tue, 11 August 2020 22:37 UTC

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From: Francis Pouatcha <fpo@adorsys.de>
Date: Tue, 11 Aug 2020 18:37:13 -0400
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To: Dick Hardt <dick.hardt@gmail.com>
Cc: Justin Richer <jricher@mit.edu>, Denis <denis.ietf@free.fr>, Benjamin Kaduk <kaduk@mit.edu>, "txauth@ietf.org" <txauth@ietf.org>
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Subject: Re: [GNAP] [Txauth] Revisiting the photo sharing example (a driving use case for the creation of OAuth)
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Hello Dick,

On Tue, Aug 11, 2020 at 6:22 PM Dick Hardt <dick.hardt@gmail.com> wrote:

> Hi Francis
>
> The user is an entity, not a role in the protocol in how I am defining
> roles, so steps (1) and (7) are confusing to me on what is happening.
>
"Requestor" is the role (*was* User). So the UML participant refers to the
role "Requestor"


> I also think that (2) could be an extension to GNAP, rather than part of
> the core protocol.
>
If you make it an extension, you hide. It shall rather be an optional,
integral part of the protocol. If the "Orchestrator/Negotiator/Client" can
translate the service request into a resource request, then there will be
no need to invoke (2).

When we move beyond identity management, cases become complex and it makes
sense to explicitly display this possibility in the protocol flow.

In some open banking designs,
- the "Orchestrator/Negotiator/Client" will not know the AS to talk to
unless the call (2).
- the request (2) might result in an exemption, meaning no need for further
authorization, allowing to skip (3, 4, 5) and even (6).

/Francis

>
>
>
>
>
> On Mon, Aug 10, 2020 at 8:04 PM Francis Pouatcha <fpo@adorsys.de> wrote:
>
>> In this context, I suggest we pick some words to work with, and sharpen
>> them as we move on, discover and map new use cases to the protocol.
>>
>> In this diagram from the original thread (
>> https://mailarchive.ietf.org/arch/msg/txauth/IaSLC_72_KimjOBJqdmQY-JOGNw/),
>> I replaced the words:
>>
>> +-----------+      +--------------+  +----+  +----+
>>  +---------------------+
>> | Requestor |      | Orchestrator |  |    |  | GS |  | Resource
>> Controller |
>> |   was     |      |     was      |  | RS |  | or |  |         was
>>  |
>> |  User     |      |   Client     |  |    |  | AS |  |    Resource Owner
>>  |
>> +-----------+      +--------------+  +----+  +----+
>>  +---------------------+
>>   |(1) ServiceRequest     |            |       |                |
>>   |---------------------->|            |       |                |
>>   |                       |(2) ServiceIntent:AuthZChallenge     |
>>   |                       |<---------->|       |                |
>>   |                       |            |       |                |
>>   |                       |(3) AuthZRequest(AuthZChallenge)     |
>>   |                       |------------------->|                |
>>   |                       |            |       |(4) ConsentRequest:Grant
>>   |                       |            |       |<-------------->|
>>   |                       |(5) GrantAccess(AuthZ)               |
>>   |                       |<-------------------|                |
>>   |                       |            |       |                |
>>   |                       |(6) ServiceRequest(AuthZ):ServiceResponse
>>   |                       |<---------->|       |                |
>>   |(7) ServiceResponse    |            |       |                |
>>   |<----------------------|            |       |                |
>>   +                       +            +       +                +
>>
>> The purpose of the GNAP protocol is to help negotiate access to a
>> protected resource. It starts with a requestor delegating activity to an
>> orchestrator. These are all roles, no entities. Let focus on mapping the
>> use cases to the protocol roles and interactions so wwe can discover what
>> is missing.
>>
>> It seems cumbersome to use it in discussions as it is impossible to give
>> the word "Client" a clear definition.
>>
>> We can mention in the final document, that the "Orchestrator" (or
>> whatever word we finally use) plays the same role as the "Client" in oAuth2.
>>
>> Best regards.
>> /Francis
>>
>>
>>
>>
>>
>> On Wed, Aug 5, 2020 at 9:05 PM Dick Hardt <dick.hardt@gmail.com> wrote:
>>
>>> I agree with Justin. Redefining well used terms will lead to significant
>>> confusion. If we have a different role than what we have had in the past,
>>> then that role should have a name not being used already in OAuth or OIDC.
>>>
>>> Given what we have learned, and my own experience explaining what a
>>> Client is, and is not, improving the definition for Client could prove
>>> useful. I am not suggesting the term be redefined, but clarified.
>>>
>>> For example, clarifying that a Client is a role an entity plays in the
>>> protocol, and that the same entity may play other roles at other times, or
>>> some other language to help differentiate between "role" and "entity".
>>>
>>> /Dick
>>> ᐧ
>>>
>>> On Wed, Aug 5, 2020 at 8:20 AM Justin Richer <jricher@mit..edu
>>> <jricher@mit.edu>> wrote:
>>>
>>>> I’m in favor of coming up with a new term that’s a better fit, but I’m
>>>> not really in favor of taking an existing term and applying a completely
>>>> new definition to it. In other words, I would sooner stop using “client”
>>>> and come up with a new, more specific and accurate term for the role than
>>>> to define “client” as meaning something completely different. We did this
>>>> in going from OAuth 1 to OAuth 2 already, moving from the
>>>> even-more-confusing “consumer” to “client”, but OAuth 2 doesn’t use the
>>>> term “consumer” at all, nor does it use “server” on its own but instead
>>>> always qualifies it with “Authorization Server” and “Resource Server”.
>>>>
>>>> GNAP can do something similar, in my opinion. But what we can’t do is
>>>> ignore the fact that GNAP is going to be coming up in a world that is
>>>> already permeated  by OAuth 2 and its terminology. We don’t have a blank
>>>> slate to work with, but neither are we bound to use the same terms and
>>>> constructs as before. It’s going to be a delicate balance!
>>>>
>>>>  — Justin
>>>>
>>>> On Aug 4, 2020, at 3:32 PM, Warren Parad <wparad@rhosys.ch> wrote:
>>>>
>>>> I think that is fundamentally part of the question:
>>>>
>>>>> We are clear that we are producing a protocol that is
>>>>> conceptually (if not more strongly) related to OAuth 2.0, and reusing
>>>>> terms
>>>>> from OAuth 2.0 but with different definitions may lead to unnecessary
>>>>> confusion
>>>>
>>>>
>>>> If we say that this document assumes OAuth2.0 terminology, then we
>>>> should not change the meanings of any definition. If we are saying this
>>>> supersedes or replaces what OAuth 2.0 creates, then we should pick the best
>>>> word for the job and ignore conflicting meanings from OAuth 2.0. I have a
>>>> lot of first hand experience of industries "ruining words", and attempting
>>>> to side-step the problem rather than redefining the word just confuses
>>>> everyone as everyone forgets the original meaning as new documents come
>>>> out, but the confusion with the use of a non-obvious word continues.
>>>>
>>>> Food for thought.
>>>> - Warren
>>>>
>>>> Warren Parad
>>>> Founder, CTO
>>>> Secure your user data and complete your authorization architecture.
>>>> Implement Authress <https://bit..ly/37SSO1p>.
>>>>
>>>>
>>>> On Tue, Aug 4, 2020 at 8:53 PM Benjamin Kaduk <kaduk@mit.edu> wrote:
>>>>
>>>>> Hi Denis,
>>>>>
>>>>> On Tue, Aug 04, 2020 at 11:31:34AM +0200, Denis wrote:
>>>>> > Hi Justin,
>>>>> >
>>>>> > Since you replied in parallel, I will make a response similar to the
>>>>> one
>>>>> > I sent to Dick.
>>>>> >
>>>>> > > Hi Denis,
>>>>> > >
>>>>> > > I think there’s still a problem with the terminology in use here.
>>>>> What
>>>>> > > you describe as RS2, which might in fact be an RS unto itself, is
>>>>> a
>>>>> > > “Client” in OAuth parlance because it is /a client of RS1/. What
>>>>> you
>>>>> > > call a “client” has no analogue in the OAuth world, but it is not
>>>>> at
>>>>> > > all the same as an OAuth client. I appreciate your mapping of the
>>>>> > > entities below, but it makes it difficult to hold a discussion if
>>>>> we
>>>>> > > aren’t using the same terms.
>>>>> > >
>>>>> > > The good news is that this isn’t OAuth, and as a new WG we can
>>>>> define
>>>>> > > our own terms. The bad news is that this is really hard to do.
>>>>> > >
>>>>> > > In GNAP, we shouldn’t just re-use existing terms with new
>>>>> definitions,
>>>>> > > but we’ve got a chance to be more precise with how we define
>>>>> things.
>>>>> >
>>>>> > In the ISO context, each document must define its own terminology.
>>>>> The
>>>>> > boiler plate for RFCs does not mandate a terminology or definitions
>>>>> section
>>>>> > but does not prevent it either. The vocabulary is limited and as
>>>>> long as
>>>>> > we clearly define what our terms are meaning, we can re-use a term
>>>>> already
>>>>> > used in another RFC. This is also the ISO approach.
>>>>>
>>>>> Just because we can do something does not necessarily mean that it is a
>>>>> good idea to do so.  We are clear that we are producing a protocol
>>>>> that is
>>>>> conceptually (if not more strongly) related to OAuth 2.0, and reusing
>>>>> terms
>>>>> from OAuth 2.0 but with different definitions may lead to unnecessary
>>>>> confusion.  If I understand correctly, a similar reasoning prompted
>>>>> Dick to
>>>>> use the term "GS" in XAuth, picking a name that was not already used in
>>>>> OAuth 2.0.
>>>>>
>>>>> -Ben
>>>>>
>>>>> --
>>>>> Txauth mailing list
>>>>> Txauth@ietf.org
>>>>> https://www.ietf.org/mailman/listinfo/txauth
>>>>>
>>>> --
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>>>>
>>>>
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>>>>
>>> --
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>>>
>>
>>
>> --
>> Francis Pouatcha
>> Co-Founder and Technical Lead
>> adorsys GmbH & Co. KG
>> https://adorsys-platform.de/solutions/
>>
>

-- 
Francis Pouatcha
Co-Founder and Technical Lead
adorsys GmbH & Co. KG
https://adorsys-platform.de/solutions/