Re: [Ace] Review of draft-ietf-ace-oauth-params-00

Ludwig Seitz <ludwig.seitz@ri.se> Wed, 24 October 2018 07:39 UTC

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From: Ludwig Seitz <ludwig.seitz@ri.se>
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Subject: Re: [Ace] Review of draft-ietf-ace-oauth-params-00
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On 23/10/2018 21:09, Hannes Tschofenig wrote:
> Hi all,
> 
> I read through draft-ietf-ace-oauth-params-00 and have a few comments.
> 
> 1) I believe the document should explain in more detail about how it 
> fits into the rest of the OAuth PoP token work.
> 

Ok I can update the introduction.

> The story essentially is that we have the HTTP-based transport in the 
> OAuth WG and we have the CoAP-based transport
> 
> in ACE. draft-ietf-ace-oauth-params-00 is about registering the 
> necessary parameters for use with CoAP only.
> 
> Neither the abstract nor the intro says this.
> 

Actually at the moment it is about registering necessary parameters for 
both HTTP and CoAP and whatever other transport you can want, since when 
I wrote it draft-ietf-oauth-pop-key-distribution was dormant.


> 2) 'req_aud' parameter
> 
> At the last IETF OAuth meeting in Montreal we agreed to adopt a new 
> document, called resource indicators, and it can be found here:
> 
> https://tools.ietf.org/html/draft-ietf-oauth-resource-indicators-01
> 

I'll have a look at that draft. How close is it to WGLC?

> 
> 3) 'req_cnf' parameter
> 
> Changing the name of the parameter name from the previous 'cnf' is good 
> and that was also requested at the last IETF due to the potential 
> confusion with the 'cnf' claim name. However, I believe the semantics is 
> different to the semantics defined in 
> draft-ietf-oauth-pop-key-distribution. Unless I misunderstand but the 
> relevant text regarding the req_cnf parameter content is this:
> 
>     o  "req_cnf" in the token request C -> AS, OPTIONAL to indicate the
> 
>        client's raw public key, or the key-identifier of a previously
> 
>        established key between C and RS that the client wishes to use for
> 
>        proof-of-possession of the access token.
> 
> For example, in draft-ietf-oauth-pop-key-distribution there is no key 
> identifier passed from the client to the server when making the request 
> for a PoP token. Instead, the server just mints one (along with the 
> symmetric key) and sends it to the client.
> 

Weird, because in the RFC7800 there is a cnf claim with just a key-id. I 
thought that you would want to be able to do something similar when 
requesting a specific, previously known key.

> PS: Why was a standalone document written instead of leaving the 
> parameters in the ACE-OAuth framework spec? I guess there are reasons 
> (which I may have missed).

The idea was that OAuth could obsolete that document when they sort the 
pop stuff out, without obsoleting the ACE framework. Thus a different 
standalone document.

/Ludwig


-- 
Ludwig Seitz, PhD
Security Lab, RISE
Phone +46(0)70-349 92 51