Re: [Ace] Requested review for IANA registration in draft-ietf-ace-oauth-params

[Seitz Ludwig <[e-mail]>]

Hello Brian,

Thank you for the re-review! Comments inline.
I will be issuing a draft update soon-ish.

/Ludwig

From: Ace <[e-mail]> On Behalf Of Brian Campbell
Sent: den 10 januari 2020 21:16
To: Ludwig Seitz <[e-mail]>
Cc: Roman Danyliw <[e-mail]>; [e-mail]; Daniel Migault <[e-mail]>; Jim Schaad <[e-mail]>; Benjamin Kaduk <[e-mail]>; [e-mail]; [e-mail]
Subject: Re: [Ace] Requested review for IANA registration in draft-ietf-ace-oauth-params

That certainly takes care of the registry conflict problem, thanks.

I'm a little confused, however, and uncertain if that changes the syntax in a way that maybe wasn't intended?

[LS] Indeed. Good catch. I amended that to say that it uses the “cnf” parameter for mtls, but for CBOR it should use the syntax of the “cnf” values from I-D.ietf-ace-cwt-proof-of-possession.

-09 had:
  cnf
     OPTIONAL.  This field contains information about the proof-of-
     possession key that binds the client to the access token.  Values
     of this parameter follow the syntax of the "cnf" claim from
     section 3.1 of [I-D.ietf-ace-cwt-proof-of-possession].  See
     Section 5 for additional discussion of the usage of this
     parameter.

while -10 has:
  Furthermore the AS can use the "cnf" parameter specified in section
  9.4 of [I-D.ietf-oauth-mtls] in an introspection response.  For CBOR-
  based interactions the AS MUST use the parameter mapping specified in
  Figure 5.

So in -09 the "cnf" Introspection Response Parameter was the following the syntax of the "cnf" claim from PoP Key Semantics for CWTs [ID.ietf-ace-cwt-proof-of-possession] and in -10 it's following the syntax of PoP Key Semantics for JWTs [RFC7800] transitively via [I-D.ietf-oauth-mtls] reference. I think I understand that the two PoP key semantics documents are conceptually the same or similar. But I don't know that the syntax is the same? Figure 5<https://tools.ietf.org/html/draft-ietf-ace-oauth-params-10#section-6> is pointed to for mapping between CBOR and JSON but it only has mappings for the main top level parameters. Maybe I just don't get it or am missing something...

[LS] No you are not missing something, I just got sloppy trying to do a quickfix.

Background: The reason for defining both JSON and CBOR-based interactions is that you might have a powerful client communicating with a constrained RS. The client does vanilla OAuth interactions with the AS via the token endpoint, but is served a CWT and associated ACE parameters (cnf, ace-profile, …) for interaction with the RS.
The pop-key should decode to the same binary representation regardless of whether it came in a JSON or CBOR wrapper.





On Tue, Jan 7, 2020 at 12:46 PM Ludwig Seitz <[e-mail]<mailto:[e-mail]>> wrote:
On 2019-12-23 22:32, Brian Campbell wrote:
> The OAuth Token Introspection Response registry
> <https://www.iana.org/assignments/oauth-parameters/oauth-parameters.xhtml#token-introspection-response>
> already has an entry for "cnf", which makes the first request in
> https://tools.ietf.org/html/draft-ietf-ace-oauth-params-07#section-9.4
> rather problematic.
>

OAuth beats us on the finish line again :-(

I have updated the draft to remove the registration and refer to the
MTLS draft.

/Ludwig

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