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

[Fabien Imbault <[e-mail]>]

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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