Re: [OAUTH-WG] Rechartering

Nat Sakimura <> Sat, 22 October 2011 14:00 UTC

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Date: Sat, 22 Oct 2011 07:00:53 -0700
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From: Nat Sakimura <>
To: Torsten Lodderstedt <>
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Cc: OAuth WG <>
Subject: Re: [OAUTH-WG] Rechartering
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Just a clarification:

Although my expired draft is 'request by reference', what was proposed
through it at the iiw really is a generalized JSON based claim request
capability. It could be passed by value as JSON or could be passed by
reference. The later is an optimization for bandwidth constrained network as
well as strengthening security in some ways. This capability already exists
in OpenID Connect but it is actually an underpinning transport, so it
probably should belong to OAuth instead. This was the primary reason for the


On Thu, Oct 20, 2011 at 3:56 PM, Torsten Lodderstedt <> wrote:

> Hi all,
> my prioritization is driven by the goal to make OAuth the authorization
> framework of choice for any internet standard protocol, such as WebDAV,
> IMAP, SMTP or SIP. So let me first explain what is missing from my point of
> view and explain some thoughts how to fill the gaps.
> A standard protocol is defined in terms of resource types and messages by a
> body (e.g. IETF, OIDF, OMA), (hopefully) implemented in many places, and
> used by different but deployment-independent clients. OAuth-based protocol
> specifications must also define scope values (e.g. read, write, send) and
> their relation to the resource types and messages. The different deployments
> expose the standard protocol on different resource server endpoints. In my
> opinion, it is fundamental to clearly distinguish scope values
> (standardized, static) and  resource server addresses (deployment specific)
> and to manage their relationships. The current scope definition is much to
> weak and insufficient. Probably, the UMA concepts of hosts, resources sets,
> and corresponding scopes could be adopted for that purpose.
> OAuth today requires clients to register with the service provider before
> they are deployed. Would you really expect IMAP clients, e.g. Thunderbird,
> to register with any a-Mail services upfront? So clients should be given a
> way to register dynamically to the authorization servers. This should also
> allow us to cover "client instance" aspects. It is interesting to note, that
> such a mechanism would allow us to get rid of secret-less clients and the
> one-time usage requirement for authorization codes.
> We also assume the client to know the URLs of the resource server and the
> corresponding authorization server and to use HTTPS server authentication to
> verify the resource server's authenticity. This is impossible in the
> standard scenario. Clients must be able to discover the authorization server
> a particular resource server relies on at runtime. The discovery mechanism
> could be specified by the OAuth WG, but could also be part of an application
> protocols specification. But we MUST find another way to prevent token
> phishing by counterfeit resource servers.
> As one approach, the client could pass the (previously HTTPS validated)
> resource server's URL with the authorization request. The authorization
> server should then refuse such requests for any unknown (counterfeit)
> resource servers. Such an additional parameter could also serve as namespace
> for scope values and enable service providers to run multiple instances of
> the same service within a single deployment.
> If the additional data enlarges the request payload to much, we could
> consider to adopt the "request by reference" proposal.
> Let's now assume, OAuth is successful in the world of standard protocols
> and we will see plenty of deployments with a bunch of different OAuth
> protected resource servers. Shall this servers all be accessible with a
> single token? In my opinion, this would cause security, privacy and/or
> scalability/performance problems. To give just the most obvious example, the
> target audience of such a token cannot be restricted enough, which may allow
> a resource server (or an attacker in control of it) to abuse the token on
> other servers. But the current design of the code grant type forces
> deployments to use the same token for all services. What is needed from my
> point of view is a way to request and issue multiple server-specific access
> tokens with a single authorization process.
> I've been advocating this topic for a long time now and I'm still convinced
> this is required to really complete the core design. We at Deutsche Telekom
> needed and implemented this function on top of the existing core. In my
> opinion, a core enhancement would be easier to handle and more powerful. If
> others support this topic, I would be willed to submit an I-D describing a
> possible solution.
> If we take standards really seriously, then service providers should be
> given the opportunity to implement their service by utilizing standard
> server implementations. This creates the challenge to find a standardized
> protocol between authorization server and resource server to exchange
> authorization data. Depending on the token design (self-contained vs.
> handle) this could be solved by either standardizing a token format (JWT) or
> an authorization API.
> Based on the rationale given above, my list is as follows (topics w/o I-D
> are marked with *):
> - Revocation (low hanging fruit since I-D is ready and implemented in some
> places)
> - Resource server notion*
> - Multiple access tokens*
> - Dynamic client registration
>  1) Dynamic Client Registration Protocol
>  4) Client Instance Extension
> - Discovery
>  (10) Simple Web Discovery, probably other specs as well
> - (6) JSON Web Token
> - (7) JSON Web Token (JWT) Bearer Profile
> - 8) User Experience Extension
> - Device flow
> - 9) Request by Reference
>  (depending resource server notion and multiple access tokens)
> regards,
> Torsten.
> Zitat von Hannes Tschofenig <>et>:
>  Hi all,
>> in preparation of the upcoming IETF meeting Barry and I would like to
>> start a re-chartering discussion.  We both are currently attending the
>> Internet Identity Workshop and so we had the chance to solicit input from
>> the participants. This should serve as a discussion starter.
>> Potential future OAuth charter items (in random order):
>> ----------------
>> 1) Dynamic Client Registration Protocol
>> Available document:
>> 2) Token Revocation
>> Available document:
>> 3) UMA
>> Available document:
>> 4) Client Instance Extension
>> Available document:
>> 5) XML Encoding
>> Available document:
>> 6) JSON Web Token
>> Available document:
>> 7) JSON Web Token (JWT) Bearer Profile
>> Available document:
>> 8) User Experience Extension
>> Available document:
>> 9) Request by Reference
>> Available document:
>> 10) Simple Web Discovery
>> Available document:
>> ----------------
>> We have the following questions:
>> a) Are you interested in any of the above-listed items? (as a reviewer,
>> co-author, implementer, or someone who would like to deploy). It is also
>> useful to know if you think that we shouldn't work on a specific item.
>> b) Are there other items you would like to see the group working on?
>> Note: In case your document is expired please re-submit it.
>> Ciao
>> Hannes & Barry
>> ______________________________**_________________
>> OAuth mailing list
> ______________________________**_________________
> OAuth mailing list

Nat Sakimura (=nat)
Chairman, OpenID Foundation