Re: [GNAP] Review of draft-ietf-gnap-core-protocol-00

[Fabien Imbault <[e-mail]>]

Ok, to be enablers of change, we'd need to specify how this would work in
detail. Again I find the objective attractive, it's just there a few
technical hurdles along the way. HTTP has never been designed for this use
case.

On Thu, Feb 4, 2021 at 7:03 PM Tom Jones <[e-mail]>
wrote:

> Justin's analysis of use of the front channel is misleading.
> It could equally be argued that what i have done is installed an AS on the
> phone and the communications with it & the PR is back channel.
> Basically the point is that the old OIDC paradigms are no longer valid.
> Be the change you want to see in the world ..tom
>
>
> On Thu, Feb 4, 2021 at 7:47 AM Fabien Imbault <[e-mail]>
> wrote:
>
>> Yes, issue (#168) message based interaction / DIDComm is a tentative
>> alternative mecanism for the interaction part. Not sure how that would work
>> in details though, prototyping will probably help here.
>> Token delivery through continuation seems fine to me. The client will
>> probably have to wait for the next polling before it receives a token
>> issued as the result of an asynchronous interaction, but that's not a big
>> issue.
>>
>> But the AS on the phone seems like a harder nut to crack, at least at
>> first sight. I think that would be awesome, but it gives me headaches, so I
>> think I'll work on easier stuff right now ;-)
>>
>> Fabien
>>
>> On Thu, Feb 4, 2021 at 4:30 PM Justin Richer <[e-mail]> wrote:
>>
>>> One of the biggest drawbacks of the current app-centric approaches in
>>> OIDC (self-issued OP, or SIOP) is that they depend on using the front
>>> channel and browser redirects to pass everything, which is something that
>>> GNAP is deliberately getting away from by starting in the back channel.
>>>
>>> That said, once a request is kicked off in GNAP, the interaction and
>>> fulfillment can happen through any number of means. Part of the work that’s
>>> being done with the “interaction” section is going to help facilitate this,
>>> and I think that there are some other potential branches here.
>>>
>>> Token delivery is where things get extra weird though — we are
>>> explicitly not delivering tokens in the front channel in the core of GNAP,
>>> we’re using the response from the continuation API. One idea (that isn’t
>>> particularly well thought out and hasn’t been implemented at all) is to
>>> have an extension declare an alternative response from the “continue”
>>> section that’s defined today, which points to the GNPA continuation API. If
>>> an extension defines some alternative way to deliver tokens, that could
>>> live alongside a continuation API and the client could indicate support for
>>> it in its initial request.
>>>
>>> In any event, alternative interaction and delivery methods are
>>> important, and even if we aren’t going to support every last one of them
>>> directly, the protocol design should at least be aware of them.
>>>
>>>  — Justin
>>>
>>> On Feb 4, 2021, at 8:35 AM, Fabien Imbault <[e-mail]>
>>> wrote:
>>>
>>> Hi Tom,
>>>
>>> Sure, any experience on that would be greatly appreciated, we're calling
>>> for help here (the point being that I suspect what they're doing is not
>>> trivial).
>>>
>>> Fabien
>>>
>>> On Thu, Feb 4, 2021 at 2:21 PM Tom Jones <[e-mail]>
>>> wrote:
>>>
>>>> I've had such an app working for over a year. There are issues which
>>>> are being addressed by the browser Interaction team of oidc.
>>>>
>>>> thx ..Tom (mobile)
>>>>
>>>> On Thu, Feb 4, 2021, 3:12 AM Fabien Imbault <[e-mail]>
>>>> wrote:
>>>>
>>>>> Hi Francis,
>>>>>
>>>>> I've tried a few things with regards to using the AS on a phone, but
>>>>> it's really quite complex.
>>>>>
>>>>> Making that run on a phone comes with quite a bit of trouble. The most
>>>>> difficult part if that we'd need to use a secure element, but just
>>>>> installing and hosting a http server securely is not a standard setup at
>>>>> all. I suggest interested people step in to work on this, as we already
>>>>> have a lot of work for the (more usual) server case and already handle a
>>>>> privacy preserving scheme.
>>>>>
>>>>> Please let us know what you think.
>>>>>
>>>>> Cheers,
>>>>> Fabien
>>>>>
>>>>> On Tue, Nov 24, 2020 at 5:55 AM Fabien Imbault <
>>>>> [e-mail]> wrote:
>>>>>
>>>>>> Hi Francis,
>>>>>>
>>>>>> I've thought a bit more to what you said. I think I'll give it a try
>>>>>> as a separate experiment (in code, not in theory). Not that I would expect
>>>>>> it to be included in GNAP, but I kind of like the idea :-)
>>>>>>
>>>>>> The direct impact for GNAP would be to think about multiple ASs.
>>>>>>
>>>>>> Will let you know.
>>>>>>
>>>>>> Fabien
>>>>>>
>>>>>>
>>>>>> Le mer. 18 nov. 2020 à 13:06, Francis Pouatcha <[e-mail]> a
>>>>>> écrit :
>>>>>>
>>>>>>> It would be nice if the protocol was designed at many layers of
>>>>>>> abstraction.
>>>>>>>
>>>>>>>
>>>>>>>    - The first layer shall design abstract protocol flows, without
>>>>>>>    specification of the mode and mechanism of interaction.
>>>>>>>    - The second layer can instantiate the first layer for dedicated
>>>>>>>    interaction. Here we can talk http, we can define interactions that presume
>>>>>>>    server based token generation, we can define interaction that run on user
>>>>>>>    device based token generation.
>>>>>>>
>>>>>>> This is also the fundament of the structure I proposed for the spec (
>>>>>>> https://github.com/ietf-wg-gnap/gnap-core-protocol/issues/30).
>>>>>>>
>>>>>>> /Francis
>>>>>>>
>>>>>>> ------------------------------
>>>>>>> *From:* Fabien Imbault <[e-mail]>
>>>>>>> *Sent:* Wednesday, November 18, 2020 6:35 AM
>>>>>>> *To:* Francis Pouatcha <[e-mail]>
>>>>>>> *Cc:* [e-mail] <[e-mail]>; Dick Hardt <
>>>>>>> [e-mail]>; Tom Jones <[e-mail]>;
>>>>>>> Denis <[e-mail]>; Justin Richer <[e-mail]>
>>>>>>> *Subject:* Re: [GNAP] Review of draft-ietf-gnap-core-protocol-00
>>>>>>>
>>>>>>> Would make sense, but not so easy as we rely heavily on HTTP. Hence
>>>>>>> the discussion about deep links and so on.
>>>>>>>
>>>>>>> An alternative might be provided by wasm/wasi (running a local
>>>>>>> sandbox on your phone, for your own AS), but it's really early stage. This
>>>>>>> also poses another question that Denis has put forward, i.e. how do we
>>>>>>> handle the multiple AS scenario (likely to occur then).
>>>>>>>
>>>>>>> Fabien
>>>>>>>
>>>>>>> On Wed, Nov 18, 2020 at 12:16 PM Francis Pouatcha <[e-mail]>
>>>>>>> wrote:
>>>>>>>
>>>>>>> We are drifting away from the original problem space.
>>>>>>>
>>>>>>>    - My original mention was about the "POST" request, that
>>>>>>>    subsumes that the "AS" is a "Server". Designing a new protocol, we cannot
>>>>>>>    afford this limitation.
>>>>>>>    - I just mentioned SIOP to show a known and closed example? Let
>>>>>>>    us not focus on the device local discovery scheme (like openid:) for now.
>>>>>>>    - As capability of holding private keys on user device evolves,
>>>>>>>    server-based issuing of token will be fading out giving way to device local
>>>>>>>    generation of token.
>>>>>>>
>>>>>>> While designing GNAP, let us assume the AS-Role can be exercised on
>>>>>>> a user device and design the protocol to honor that.
>>>>>>>
>>>>>>> Best regards,
>>>>>>> /Francis
>>>>>>> ------------------------------
>>>>>>> *From:* TXAuth <[e-mail]> on behalf of Dick Hardt <
>>>>>>> [e-mail]>
>>>>>>> *Sent:* Tuesday, November 17, 2020 1:28 PM
>>>>>>> *To:* Tom Jones <[e-mail]>
>>>>>>> *Cc:* Fabien Imbault <[e-mail]>; Denis <
>>>>>>> [e-mail]>; GNAP Mailing List <[e-mail]>; Justin
>>>>>>> Richer <[e-mail]>
>>>>>>> *Subject:* Re: [GNAP] Review of draft-ietf-gnap-core-protocol-00
>>>>>>>
>>>>>>> Got it.
>>>>>>>
>>>>>>> So web apps invoke a openid: deep link and hope there is an app to
>>>>>>> handle the openid: scheme? ... and that it is the user's wallet rather than
>>>>>>> some malware that has registered openid: on the mobile device?
>>>>>>>
>>>>>>> A native app can attempt to open a deep link associated with an app,
>>>>>>> and will fail if the app is not there. If the app is there, it will be
>>>>>>> opened, so this can't be used to silently test if an app is present, but it
>>>>>>> does allow a native app to provide an alternative experience if an app is
>>>>>>> not present. I don't think this works with custom schemes ... and I don't
>>>>>>> know how it could work from a web app on the phone with the current Safari
>>>>>>> APIs.
>>>>>>>
>>>>>>> Apple warns against using custom schemes [1] ... but perhaps they
>>>>>>> can be convinced to make openid: a managed scheme similar to mailto:,
>>>>>>> tel:, sms:, facetime: ?
>>>>>>>
>>>>>>> [1]
>>>>>>> https://developer.apple.com/documentation/xcode/allowing_apps_and_websites_to_link_to_your_content/defining_a_custom_url_scheme_for_your_app
>>>>>>>
>>>>>>>
>>>>>>> ᐧ
>>>>>>>
>>>>>>> On Tue, Nov 17, 2020 at 10:06 AM Tom Jones <
>>>>>>> [e-mail]> wrote:
>>>>>>>
>>>>>>> You are - that is not standard which is opeind://
>>>>>>> This is the one step that still needs to be optimized for SIOP to
>>>>>>> have good UX.
>>>>>>> Peace ..tom
>>>>>>>
>>>>>>>
>>>>>>> On Tue, Nov 17, 2020 at 9:59 AM Dick Hardt <[e-mail]>
>>>>>>> wrote:
>>>>>>>
>>>>>>> Hi Tom
>>>>>>>
>>>>>>> I watched your video (I watched at 2X speed)
>>>>>>>
>>>>>>> Looks like the employment website app that is using localhost:8765
>>>>>>> to communicate with the wallet. Am I correct?
>>>>>>>
>>>>>>> /Dick
>>>>>>> ᐧ
>>>>>>>
>>>>>>> On Tue, Nov 17, 2020 at 9:46 AM Tom Jones <
>>>>>>> [e-mail]> wrote:
>>>>>>>
>>>>>>> Well, here's a demo. Note that in this case the AS is not online all
>>>>>>> of the time, so it is really implicit flow and the OIDC id-token comes from
>>>>>>> the siop device directly.
>>>>>>> (whether this is front-channel or back channel is no longer an
>>>>>>> interesting question.)
>>>>>>> Now if an always-on AS is required, that is possible, but probably
>>>>>>> beyond the scope of this effort and would require something like an
>>>>>>> agent-in-the-sky (with diamonds).
>>>>>>> here is the link to the 9 min video   https://youtu.be/Tq4hw7X5SW0
>>>>>>> <https://urldefense.us/v2/url?u=https-3A__youtu.be_Tq4hw7X5SW0&d=DwMFaQ&c=2plI3hXH8ww3j2g8pV19QHIf4SmK_I-Eol_p9P0CttE&r=D5lnfoa2MVZWELqVbbz71ooelbP7rVGCjGDSBNvUpYQ&m=ixsudGSr_dhG-SLiatb4Sz9FWslmywnYyZAOLgZxhl8&s=jdLLy0G1JTQCAOBZ6PeUgI0kiCtVJXrru0VToYWlNZ8&e=>
>>>>>>> Peace ..tom
>>>>>>>
>>>>>>>
>>>>>>> On Tue, Nov 17, 2020 at 9:20 AM Justin Richer <[e-mail]>
>>>>>>> wrote:
>>>>>>>
>>>>>>> Ultimately, in most situations like these in the real world, the
>>>>>>> hurdle isn’t technical compatibility so much as it is trust compatibility.
>>>>>>> The RP (client) needs to have some incentive to trust the assertions and
>>>>>>> identity information that’s coming from the AS. The same is true for an RS
>>>>>>> trusting tokens from the AS. The hard question is less “how” to do that
>>>>>>> (which SSI answers), but more “why” to do that (which SSI doesn’t answer
>>>>>>> very well, because it’s a hard question).
>>>>>>>
>>>>>>> Still: it’s definitely a question about how to support this “AS on
>>>>>>> device” element. We’ve got the start of it more than OAuth2/OIDC have by
>>>>>>> allowing the bootstrap of the process from a starting call: the interaction
>>>>>>> and continuation URIs handed back by the AS don’t need to be the same URIs
>>>>>>> that the client starts with, so just like SIOP the process can start in
>>>>>>> HTTP and potentially move to other communication channels. A major
>>>>>>> difference is that we aren’t dependent on the assumption that the user will
>>>>>>> always be in a browser at some stage, and so the whole raft of
>>>>>>> front-channel messages that SIOP relies on doesn’t fly. That said, we’ve
>>>>>>> got an opportunity to more explicitly open up alternative communication
>>>>>>> channels here, and that’s something I’d like to see engineered, even if
>>>>>>> it’s an extension. I’d love to see a concrete proposal as to how that would
>>>>>>> work over specific protocols, starting with what we’ve got today.
>>>>>>>
>>>>>>>  — Justin
>>>>>>>
>>>>>>> On Nov 17, 2020, at 12:03 PM, Fabien Imbault <
>>>>>>> [e-mail]> wrote:
>>>>>>>
>>>>>>> Hi Denis, hi Francis,
>>>>>>>
>>>>>>> At some point integration with SSI (on the authentication side) will
>>>>>>> probably occur, including amongst other possibilities SIOP (since they work
>>>>>>> with OpenID a part of the work will probably be made easier).
>>>>>>>
>>>>>>> That being said, Denis is right. It's not an AS. Technically it's
>>>>>>> entirely possible to rely on a decentralized wallet (for instance on your
>>>>>>> phone) and a centralized AS. I know of a few studies on how to decentralize
>>>>>>> the AS itself (for instance
>>>>>>> https://tools.ietf.org/html/draft-hardjono-oauth-decentralized-02).
>>>>>>> Maybe it exists, but I'm still looking for real scenarios (or even
>>>>>>> architectures) where an AS is deployed directly on a phone, and under the
>>>>>>> sole authority of the RO, while being compatible with the rest of the
>>>>>>> world.
>>>>>>>
>>>>>>> Cheers,
>>>>>>> Fabien
>>>>>>>
>>>>>>> On Tue, Nov 17, 2020 at 5:45 PM Denis <[e-mail]> wrote:
>>>>>>>
>>>>>>> Hello  Francis,
>>>>>>>
>>>>>>> See two comments in line.
>>>>>>>
>>>>>>>
>>>>>>> B) Current Document
>>>>>>>
>>>>>>> Roles description shall not hold any assumption on the physical
>>>>>>> structure of the party fulfilling the roles.
>>>>>>> [FI] not sure what you mean
>>>>>>>
>>>>>>>  [FP] for example, we assume the AS is a server! In most SSI based
>>>>>>> use cases, the AS will be running on the user device. See SIOP (
>>>>>>> https://identity.foundation/did-siop/).
>>>>>>>
>>>>>>> I browsed through the two drafts, i.e. :
>>>>>>>
>>>>>>>    - Decentralized Identifiers (DIDs) v1.0 Core architecture, data
>>>>>>>    model, and representations W3C Working Draft 08 November 2020
>>>>>>>    - Self-Issued OpenID Connect Provider DID Profile v0.1. DIF
>>>>>>>    Working Group Draft
>>>>>>>
>>>>>>> At no place within these two documents, it is possible to imagine
>>>>>>> that "the AS will be running on the user device".
>>>>>>>
>>>>>>> From section 3 of the DIF Working Group Draft:
>>>>>>>
>>>>>>>       "Unlike the OIDC Authorization Code Flow as per [OIDC.Core],
>>>>>>> the SIOP will not return an access token to the RP".
>>>>>>>
>>>>>>> An Identity Wallet is not an AS.
>>>>>>>
>>>>>>>
>>>>>>> Roles:
>>>>>>> -> grant endpoint of the AS: Why is this a post request? This
>>>>>>> eliminates the chance of having user device hosted AS (no server).
>>>>>>> [FI] what would you propose instead?
>>>>>>> Would also be interested to understand better the deployment model
>>>>>>> when there is no server. That's something that was discussed several times
>>>>>>> but I'm still missing the underlying architecture and use case.
>>>>>>>
>>>>>>>  [FP] See above (SIOP). There will be a lot of identity wallets
>>>>>>> operated on end user device.
>>>>>>>
>>>>>>> See the above comment. Please, do not confuse an Identity Wallet
>>>>>>> with an Authentication Server (AS).
>>>>>>>
>>>>>>> Denis
>>>>>>>
>>>>>>>
>>>>>>> -> Resource Owner (RO) : Authorizes the request? Does it authorize
>>>>>>> the request or the access to a resource?
>>>>>>> [FI] yes, we should make the wording clearer
>>>>>>>
>>>>>>> Missing Section Interactions:
>>>>>>> --> This section shall introduce the notion of interaction before we
>>>>>>> start listing interaction types.
>>>>>>> [FI] yes
>>>>>>>
>>>>>>> Interaction Types:
>>>>>>> --> I prefer a classification with Redirect, Decoupled and Embedded
>>>>>>> is. In the draft, we have one redirect and 2 decouple interactions and
>>>>>>> nothing else.
>>>>>>> [FI] this should be handled as a specific discussion item. As a
>>>>>>> reminder, how would you define embedded?
>>>>>>>
>>>>>>> In practice there's at least these modes:
>>>>>>> - redirect and redirect back
>>>>>>> - redirect to different browser or device
>>>>>>> - user code
>>>>>>> - CIBA
>>>>>>>
>>>>>>> [FP] This classification is limited.
>>>>>>>
>>>>>>>    - Redirect: same device, same or different user agents (browser,
>>>>>>>    mobile app, desktop app, ...)
>>>>>>>    - Decoupled: different devices
>>>>>>>    - Embedded : RC carries RO authorization to AS
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> Resource Access Request vs. Resource Request
>>>>>>> --> Both are mixed up. No clarification of the context of each
>>>>>>> section.
>>>>>>> [FI] could you clarify what you'd expect.  Btw on this topic,
>>>>>>> there's a more general discussion on whether we should make a distinction
>>>>>>> or not.
>>>>>>>
>>>>>>> ​[FP]: Here:
>>>>>>>
>>>>>>>    - Resource Access Request: Requesting Access to a resource.
>>>>>>>    Response is an access token (or any type of grant)
>>>>>>>    - Resource Request: Request the resource. Response is the
>>>>>>>    resource (or a corresponding execution)
>>>>>>>
>>>>>>>
>>>>>>> Token Content Negotiation
>>>>>>> --> Not expressed as such. This is central to GNAP and not
>>>>>>> represented enough  in the document.
>>>>>>> [FI] right. This should be a specific discussion item.
>>>>>>>
>>>>>>> Requesting "User" Information
>>>>>>> we identify two types of users: RQ and RO. It will be better not to
>>>>>>> refer to a user in this draft, but either to a RQ or an RO.
>>>>>>> [FI] yes that would avoid potential misunderstandings. Although in
>>>>>>> the end, people will translate RQ into user or end-user most of the time.
>>>>>>> Cf in definition, currently we have Requesting Party (RQ, aka
>>>>>>> "user")
>>>>>>>
>>>>>>>
>>>>>>> Interaction Again
>>>>>>> -> For each interaction type, we will have to describe the protocol
>>>>>>> flow and the nature and behavior of involved Roles (Parties), Elements,
>>>>>>> Requests.
>>>>>>> [FI] yes
>>>>>>>
>>>>>>>
>>>>>>> [FP] Will these and into tickets?
>>>>>>>
>>>>>>> Best regards.
>>>>>>> /Francis
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> --
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