Re: [Txauth] Call for charter consensus - TxAuth WG

[Justin Richer <[e-mail]>]

I agree with a lot of that argument. Let me see if I can more clearly restate what I was trying to say earlier in this thread: the relationships between the different parties are separable and depend on the kind of deployments and use cases that are being addressed by people. So in an OAuth/OIDC-style world, we’ve got three components (ignoring people), and three relationships between them:

C<->AS

C<->RS

AS<->RS

For authorization, these map to “how to get a token”, “how to use a token”, and “how to interpret a token”. For authentication, it’s additionally “how do I get the authentication info”, “how do I ask for a profile”, and “how do I know whose profile this is”. I still believe this is a good separation of concerns. The client doesn’t need to know what’s in the access token, or if it’s a reference or self-contained, or really concern itself at all with what the RS does with it. Are there overlaps? Certainly — the client needs to know how to ask for a token that the RS will accept for what the client is going to do, and to do that the client needs to be able to describe what it wants to do in a way that the AS can interpret and map to a set of rights that the RS will eventually interpret. 

I believe the proposed charter already covers this split with the following items:

- Fine-grained specification of access
- Approval of access to multiple resources and APIs in a single interaction
- Separation between the party authorizing access and the party operating the client requesting access
- Revocation of active tokens
- Query of token rights by resource servers

It’s the combination of the rich request and the lifecycle management that puts the AS and RS in scope. I think things like declaring a single token format are absolutely out — if you want to use JWT, or CWT, or UUID’s, that’s all just fine. However, something that I think is in scope is defining a structure for what a token represents. And I think that if we can do that in this WG in a general way, then that’s useful. Because then that structure can be represented by mapping to a token format or an introspection response or a database entry. I think Nat’s comments on ABAC are important: we are going to need a place to put those attributes. Whether they’re communicated to the RS through the token itself or through some other channel is, I strongly believe, a matter of deployment choice.

So, what can the charter say to make this more clear?

All that said, I’m against having an architecture document as a working group output. In my experience, when a WG puts its effort into a formal architecture doc as a deliverable, there is a lot of conjectural energy that goes into what might be a good idea, and then not all of it works out when you try to hammer the details of making that architecture into a real engineered thing.You end up baking in assumptions and abstractions that don’t make sense anymore, and then trying to engineer solutions around those when they don’t fit right. If the architecture can’t change in light of new information, which is the case with an RFC, then it becomes a shackle instead of a scaffold. But a malleable document that the group can use as a guide while engineering the actual parts — yes, that makes sense. The architecture can be refactored and changed as decisions are made and things come into focus. I feel the same about use case documents as formal artifacts. 

Thanks, Nat.
 — Justin

> On Mar 20, 2020, at 2:19 AM, Nat Sakimura <[e-mail]> wrote:
> 
> I thought I should keep my mouth shut as anything I say may be deemed biased as my other hat is the chairman of OIDF, but here is my 2c. 
> 
> As Torsten indicated, there is much to be desired to standardize the AS - RS communication patterns. You may say that the charter includes it, but I cannot read it out of the charter just like Torsten could not. As a new protocol, it would be good to include it. 
> 
> In this respect, I am not sure if we should start off from OAuth 2.0 and OIDC model. If we are creating a new protocol, I feel that we should architect is more fully. Not mentioning AS - RS relationship to me feels like an indication of this failure. For that matter, I feel that the first output of the group should be an architecture document that takes the concerns from all the relevant stakeholders/actors in. 
> 
> We should also be cognizant of the access control models like ABAC. For that, decoupling of identity (= set of claims) assertion and authorization is a necessity. We could optimize it but the base case should take care of it. (In this respect, I am feeling that OIDC has perhaps over-optimized.) So, I feel that at least as the first step, TxAuth should concentre on the Access Control. If I were to go one step further, it should be modelled so that it can consume various identity assertions (authenticated identity in ISO/IEC 24760 speak) including ID Token, SAML Assertion, DID Verifiable Credentials, X.509 certificates (such as in eIDAS and Japanese National ID scheme)  etc. We are not going to get to a unified identity world anytime soon. 
> 
> Cheers, 
> 
> Nat Sakimura
> 
> 
> On Wed, Mar 18, 2020 at 7:06 AM Mike Jones <Michael.Jones=[e-mail] <mailto:[e-mail]>> wrote:
> I believe it's significant that four people have expressed concerns with including digital identity in the charter (the only concerns voiced as far as I can tell).  At a minimum, I believe that that warrants making the inclusion or exclusion of digital identity a discussion topic during the upcoming virtual BoF, before adopting any charter.
> 
> It would be my proposal to initially charter without digital identity and see how far we get with our energies intentionally focused in that way.  If the working group decides to recharter to include digital identity, that can always happen later, after the authorization-focused work has matured, and once there's a clear case to actually do so.
> 
>                                 -- Mike
> 
> -----Original Message-----
> From: Justin Richer <[e-mail] <mailto:[e-mail]>> 
> Sent: Tuesday, March 17, 2020 2:20 PM
> To: Mike Jones <[e-mail] <mailto:[e-mail]>>
> Cc: Yaron Sheffer <[e-mail] <mailto:[e-mail]>>; Torsten Lodderstedt <[e-mail] <mailto:[e-mail]>>; [e-mail] <mailto:[e-mail]>
> Subject: Re: [Txauth] Call for charter consensus - TxAuth WG
> 
> While I understand the concerns around identity in the charter, and I had initially not included it, I was convinced that the kind of identity protocol that we’re looking at here is a minor addition to the authorization and delegation end of things.
> 
> As you know, much of what’s in OIDC is there to fix problems with OAuth 2 when it’s used for identity. If OAuth 2 had solved those problems internally, then OIDC would be much, much simpler and smaller. We’re now starting at a base where those problems don’t exist, but we don’t yet know what other problems there might be. 
> 
> The market has shown us that the most common application of OAuth 2 is far and away access to identity information along side access to an API. I think we need to pay attention to that and not make this separate just because we did it that way before. And some of the proposed innovations, including getting and sending VC’s, are all about identity.
> 
> Furthermore, this charter does not specify the document and specification structure of the components, nor does it specify the publication order or timing of any documents. I personally think that the identity layer should be separable to an extent, to the point of publishing that layer in its own spec alongside the core authorization delegation system. However, that does not mean that it should be developed elsewhere.
> 
> If there is better language to tighten the aspects of an identity protocol that we will explicitly cover, then I would welcome you to suggest an amended text to the charter. However, I believe there is enough interest within the community to work on identity in the context of this protocol, including a large number of people being OK with it in the charter, that it would not be a reasonable thing to remove it.
> 
>  — Justin
> 
> > On Mar 17, 2020, at 1:12 PM, Mike Jones <Michael.Jones=[e-mail] <mailto:[e-mail]>> wrote:
> > 
> > 1.  Do you support the charter text provided at the end of this email?  Or do you have major objections, blocking concerns or feedback (if so please elaborate)?
> > 
> > I share the concerns about including identity in the charter that were expressed by Torsten and agreed with by David Skaife.  I'll note that Kim Cameron previously expressed concerns about including identity in his earlier charter critique at https://mailarchive.ietf.org/arch/msg/txauth/uL92O_Vk5m38DcacXSnshX2CahE/ <https://mailarchive.ietf.org/arch/msg/txauth/uL92O_Vk5m38DcacXSnshX2CahE/>.
> > 
> > I'm fine with refactoring the authorization protocol.  But identity should be decoupled from the TxAuth work to focus its scope on areas where innovation is being proposed.  Digital identity can always be added as a layer if needed, just as OpenID Connect layered identity onto OAuth 2.0.
> > 
> > Please revise the charter to remove digital identity from the scope of the work.
> > 
> > 2.  Are you willing to author or participate in the development of the drafts of this WG?
> > 
> > Yes
> > 
> > 3.  Are you willing to help review the drafts of this WG?
> > 
> > Yes
> > 
> > 4.  Are you interested in implementing drafts of this WG?
> > 
> > Not at this time.
> > 
> >                               -- Mike
> > 
> > -----Original Message-----
> > From: Txauth <[e-mail] <mailto:[e-mail]>> On Behalf Of Torsten Lodderstedt
> > Sent: Saturday, March 7, 2020 7:18 AM
> > To: Yaron Sheffer <[e-mail] <mailto:[e-mail]>>
> > Cc: [e-mail] <mailto:[e-mail]>
> > Subject: [EXTERNAL] Re: [Txauth] Call for charter consensus - TxAuth WG
> > 
> > Hi,
> > 
> >> Am 06.03.2020 um 17:45 schrieb Yaron Sheffer <[e-mail] <mailto:[e-mail]>>:
> >> 
> >> Hi Everyone,
> >> 
> >> It appears that momentum is forming around the proposed formation of a TxAuth working group.  We’d like to more formally gauge interest in proceeding with this work.  Please do so by responding to the following questions:
> >> 
> >> 1.  Do you support the charter text provided at the end of this email?  Or do you have major objections, blocking concerns or feedback (if so please elaborate)?
> > 
> > I‘m in although I have to admit I‘m slightly concerned the scope of the charter is too broad, e.g. identify alone is a huge topic.
> > 
> > We need to keep an eye on this aspect in order to make sure, the group is able to work effectively and the specs we will be producing are as simple as possible and foster interoperability.
> > 
> >> 
> >> 2.  Are you willing to author or participate in the development of the drafts of this WG?
> > 
> > yes
> > 
> >> 
> >> 3.  Are you willing to help review the drafts of this WG?
> > 
> > yes
> > 
> >> 
> >> 4.  Are you interested in implementing drafts of this WG?
> > 
> > yes
> > 
> > best regards,
> > Torsten.
> > 
> >> 
> >> The call will run for two weeks, until March 21. If you think that the charter should be amended In a significant way, please reply on a separate thread.
> >> 
> >> The feedback provided here will help the IESG come to a decision on the formation of a new WG. Given the constraints of the chartering process, regardless of the outcome of this consensus call, we will be meeting in Vancouver as a BoF.
> >> 
> >> Thanks,
> >> Yaron and Dick
> >> 
> >> --- Charter Text Follows ---
> >> 
> >> This group is chartered to develop a fine-grained delegation protocol for authorization, identity, and API access. This protocol will allow an authorizing party to delegate access to client software through an authorization server. It will expand upon the uses cases currently supported by OAuth 2.0 and OpenID Connect (itself an extension of OAuth 2.0) to support authorizations scoped as narrowly as a single transaction, provide a clear framework for interaction among all parties involved in the protocol flow, and remove unnecessary dependence on a browser or user-agent for coordinating interactions. 
> >> 
> >> The delegation process will be acted upon by multiple parties in the protocol, each performing a specific role. The protocol will decouple the interaction channels, such as the end user’s browser, from the delegation channel, which happens directly between the client and the authorization server (in contrast with OAuth 2.0 which is initiated by the client redirecting the user’s browser). The client and AS will involve a user to make an authorization decision as necessary through interaction mechanisms indicated by the protocol. This decoupling avoids many of the security concerns and technical challenges of OAuth 2.0 and provides a non-invasive path for supporting future types of clients and interaction channels.
> >> 
> >> Additionally, the delegation process will allow for:
> >> 
> >> - Fine-grained specification of access
> >> - Approval of AS attestation to identity claims
> >> - Approval of access to multiple resources and APIs in a single interaction
> >> - Separation between the party authorizing access and the party operating the client requesting access
> >> - A variety of client applications, including Web, mobile, single-page, and interaction-constrained applications
> >> 
> >> The group will define extension points for this protocol to allow for flexibility in areas including:
> >> 
> >> - Cryptographic agility for keys, message signatures, and proof of possession 
> >> - User interaction mechanisms including web and non-web methods
> >> - Mechanisms for conveying user, software, organization, and other pieces of information used in authorization decisions
> >> - Mechanisms for presenting tokens to resource servers and binding resource requests to tokens and associated cryptographic keys
> >> - Optimized inclusion of additional information through the delegation process (including identity)
> >> 
> >> Additionally, the group will provide mechanisms for management of the protocol lifecycle including:
> >> 
> >> - Discovery of the authorization server
> >> - Revocation of active tokens
> >> - Query of token rights by resource servers
> >> 
> >> Although the artifacts for this work are not intended or expected to be backwards-compatible with OAuth 2.0 or OpenID Connect, the group will attempt to simplify migrating from OAuth 2.0 and OpenID Connect to the new protocol where possible.
> >> 
> >> This group is not chartered to develop extensions to OAuth 2.0, and as such will focus on new technological solutions not necessarily compatible with OAuth 2.0. Functionality that builds directly on OAuth 2.0 will be developed in the OAuth Working Group, including functionality back-ported from the protocol developed here to OAuth 2.0.
> >> 
> >> The group is chartered to develop mechanisms for applying cryptographic methods, such as JOSE and COSE, to the delegation process. This group is not chartered to develop new cryptographic methods. 
> >> 
> >> The initial work will focus on using HTTP for communication between the client and the authorization server, taking advantage of optimization features of HTTP2 and HTTP3 where possible, and will strive to enable simple mapping to other protocols such as COAP when doing so does not conflict with the primary focus.
> >> 
> >> Milestones to include:
> >> - Core delegation protocol
> >> - Key presentation mechanism bindings to the core protocol for TLS, detached HTTP signature, and embedded HTTP signatures
> >> - Identity and authentication conveyance mechanisms
> >> - Guidelines for use of protocol extension points
> >> 
> >> 
> >> -- 
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> >> [e-mail] <mailto:[e-mail]>
> >> https://www.ietf.org/mailman/listinfo/txauth <https://www.ietf.org/mailman/listinfo/txauth>
> > -- 
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> 
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> 
> -- 
> Nat Sakimura (=nat)
> Chairman, OpenID Foundation
> http://nat.sakimura.org/ <http://nat.sakimura.org/>
> @_nat_en