Re: [OAUTH-WG] tsv-dir review of draft-ietf-oauth-v2-23

Justin Richer <jricher@mitre.org> Wed, 15 February 2012 13:46 UTC

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Date: Wed, 15 Feb 2012 08:44:24 -0500
From: Justin Richer <jricher@mitre.org>
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Subject: Re: [OAUTH-WG] tsv-dir review of draft-ietf-oauth-v2-23
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On 02/15/2012 04:33 AM, Songhaibin wrote:
> I've reviewed this document as part of the transport area directorate's ongoing effort to review key IETF documents. These comments were written primarily for the transport area directors, but are copied to the document's authors for their information and to allow them to address any issues raised. The authors should consider this review together with any other last-call comments they receive. Please always CC tsv-dir@ietf.org if you reply to or forward this review.
>
> First, I should apologize for the delay in this review, I should have finished it two days ago. I have some common security knowledge but not an expert.
>
> Summary
>
> This draft is basically ready for publication, but has nits that should be fixed before publication.
>
> General issues need discussion:
>
> 1. Section 1.3.3 and 1.3.4 discuss two authorization grant type: resource owner password credentials, and client credentials. These two have the same flow and many in common, and they are significantly different than the authorization code grant type and implicit grant type described in previous sections. And in section 1.3.4, it also says " Client credentials are used as an authorization grant typically when the client is acting on its own behalf (the client is also the resource owner),...". Is it better to combine these two grant types as one "client credentials" grant type where the client can be the resource owner?

No, they are quite distinct -- It all comes down to what you're 
authenticating. The Resource Owner Password Credentials flow *also* 
includes client credentials which are distinct from the resource owner's 
own credentials. The client's credentials are going to be the same for a 
given client across many different users, while the Resource Owner's 
credentials are going to be different across different users, but the 
same across different clients (for the same resource owner). In most 
flows, the client's credentials identify just the client, and the 
resource owner is identified through some other means (a direct 
password, a redirected login to the authz endpoint). In the Client 
Credentials flow, the client's credentials are the only ones that you have.

> 2. Two concepts confused me in section 2.4, I don't know if I am the only person who is confusing here. One is user-agent-based application and another is native application, why are they executed on the device used by the resource owner? I think they can run on any device used by resource consumer instead of resource owner. Resource owner is only used to grant access to resources.

OAuth's main 3-legged pattern allows what's called "Alice-to-Alice 
sharing", in that the Client is consuming on behalf of the resource 
owner. In cases where you have an in-user-agent app or a native app, the 
end user (resource owner) is going to be the one running it, and the one 
authorizing it.


Thanks for your feedback, and I hope this can help clear up the intent 
of the working group here. If you can suggest language that will 
solidify these points further, it can help make sure this doesn't 
further confuse people.

  -- Justin