Re: [Ace] AIF as discussed today (Re: I-D Action: draft-bormann-core-ace-aif-08.txt)

> -----Original Message-----
> From: Ace <ace-bounces@ietf.org> On Behalf Of Francesca Palombini
> Sent: Tuesday, June 23, 2020 6:45 AM
> To: Carsten Bormann <cabo@tzi.org>; Ace Wg <ace@ietf.org>
> Cc: Marco Tiloca <marco.tiloca@ri.se>
> Subject: Re: [Ace] AIF as discussed today (Re: I-D Action: draft-bormann-core-
> ace-aif-08.txt)
> 
> Hi Carsten,
> 
> Thanks for this quick update! Just some short high level comments, to make
> sure we can use this for ace-key-groupcomm-oscore.
> 
> In ace-key-groupcomm-oscore, we would say that Toid is the identifier of the
> OSCORE group, so the OSCORE "group name", which is encoded as a bstr. For
> Tperm, it's a bit further away from what the aif document specifies (which is
> why I want to check with you), but we would go for array of tstr, since we can't
> really encode the permission to be a "monitor" node (for example) by
> indicating a REST method. This is a bit stretched from the document right now,
> but it should work.
> 
> We would have to register a media type (and content format) for this, so what
> would this be? You use aif+cbor for the default, so maybe something like "aif-
> ace-group+cbor". For section 5.3, we would have to register Toid and Tperm
> with something like:
> 
> Toid registry:
> * name: gname
> * description: group name of the OSCORE group as specified in ace-key-
> groupcomm-oscore
> 
> Tperm registry:
> * name: roles
> * description: role of the group member as specified in ace-key-groupcomm-
> oscore
> 
> I think we are missing some form of "encoding" column in the registries above.
> In that case it would be "bstr" for Toid gname and "CBOR array of tstr" for
> Tperm role. It would also be "tstr" for local-part Toid and "int" for Tperm REST-
> method-set. (also, minor, but you sometimes use "local-part" and sometimes
> "local-uri", see section 4). Even better, the description or the encoding in the
> registry could point to "path" and "permissions" cddl, for the default values in
> the aif doc.
> 
> Using "array of tstr" for roles allows us to express what we need for "set of
> roles". I don't see this being in contrast with the aif document right now.

This follows what I would expect, for MQTT I would see

AIF-MQTT = AIF_Generic<filter, permissions>
filter = tstr
permissions = [ +permission ]
permission = "publish" / "subscribe"

For the group comm draft, I think that

AIF-GROUP-COM = AIF_Generic<path, permisions>
path = tstr  ; group name
permissions = uint . bits methods
methods = &(
    requester = 1,
   responder = 2,
   monitor = 3,
   verifier = 4
)

This does require a registry if we ever expect this to grow.

> So all in all, I think this can work for ace-key-groupcomm-oscore. Please let me
> know if you see anything that bothers you in my summary.
> 
> Thanks,
> Francesca
> 
> On 23/06/2020, 00:17, "Ace on behalf of Carsten Bormann" <ace-
> bounces@ietf.org on behalf of cabo@tzi.org> wrote:
> 
>     I went ahead and quickly implemented what we had discussed today.
> 
>     https://www.ietf.org/id/draft-bormann-core-ace-aif-08.html
> 
>     Lots more editing to do, but the gist of what I was trying to say should be
> there.
>     Comments welcome!
> 
>     Grüße, Carsten
> 
> 
>     > On 2020-06-23, at 00:12, internet-drafts@ietf.org wrote:
>     >
>     >
>     > A New Internet-Draft is available from the on-line Internet-Drafts
> directories.
>     > This draft is a work item of the Authentication and Authorization for
> Constrained Environments WG of the IETF.
>     >
>     >        Title           : An Authorization Information Format (AIF) for ACE
>     >        Author          : Carsten Bormann
>     > 	Filename        : draft-bormann-core-ace-aif-08.txt
>     > 	Pages           : 9
>     > 	Date            : 2020-06-22
>     >
>     > Abstract:
>     >   Constrained Devices as they are used in the "Internet of Things" need
>     >   security.  One important element of this security is that devices in
>     >   the Internet of Things need to be able to decide which operations
>     >   requested of them should be considered authorized, need to ascertain
>     >   that the authorization to request the operation does apply to the
>     >   actual requester, and need to ascertain that other devices they place
>     >   requests on are the ones they intended.
>     >
>     >   To transfer detailed authorization information from an authorization
>     >   manager (such as an ACE-OAuth Authorization Server) to a device, a
>     >   representation format is needed.  This document provides a suggestion
>     >   for such a format, the Authorization Information Format (AIF).  AIF
>     >   is defined both as a general structure that can be used for many
>     >   different applications and as a specific refinement that describes
>     >   REST resources and the permissions on them.
>     >
>     >
>     > The IETF datatracker status page for this draft is:
>     > https://datatracker.ietf.org/doc/draft-bormann-core-ace-aif/
>     >
>     > There are also htmlized versions available at:
>     > https://tools.ietf.org/html/draft-bormann-core-ace-aif-08
>     > https://datatracker.ietf.org/doc/html/draft-bormann-core-ace-aif-08
>     >
>     > A diff from the previous version is available at:
>     > https://www.ietf.org/rfcdiff?url2=draft-bormann-core-ace-aif-08
>     >
>     >
>     > Please note that it may take a couple of minutes from the time of
> submission
>     > until the htmlized version and diff are available at tools.ietf.org.
>     >
>     > Internet-Drafts are also available by anonymous FTP at:
>     > ftp://ftp.ietf.org/internet-drafts/
>     >
>     >
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