Hi Olaf,

Thank you for the quick update!

Please, see my replies inline (trimming the solved points)


On 2022-02-18 13:42, Olaf Bergmann wrote:
Hi Marco,

thanks for the thorough review. I have done most of the suggested
updates (see Editor's copy [1]).

Just a few comments and questions inline.

[1] 
https://ace-wg.github.io/ace-extend-dtls-authorize/draft-ietf-ace-extend-dtls-authorize.html

On 2022-02-18, Marco Tiloca <[email protected]> wrote:

[Section 1]

* For consistency with draft-ietf-ace-dtls-authorize , I think
here it would be better to refer to RFC 6347 when mentioning
DTLS. The original profile only mentions DTLS 1.3 as a possible
later version, without pointing to the specification.
Done.

DTLS1.3 now is not referenced anymore. Do you think a normative
dependency for DTLS1.3 is required?

==>MT
I think you can remove the DTLS 1.3 entry from the list of normative references. That reference is not present among those in draft-ietf-ace-dtls-authorize either (where DTLS 1.3 is at least named once), so it feels even more unnecessary here.
<==
* "The same access rights are valid in case transport layer
security is either DTLS or TLS, and the same access token can be
used."

    This implies that the "ace_profile" claim in the access token
and the corresponding "ace_profile" parameter in the AS-to-Client
response still indicate the profile name "coap_dtls", even though
TLS might be used between C and RS. I think it's better to
highlight it.
Yes, good point.

I have added the following sentence at the end:

   Therefore, the value `coap_dtls` in the `ace_profile` parameter of
   an AS-to-Client response or in the `ace_profile` claim of an
   access token indicates that either DTLS or TLS can be used for
   transport layer security.

==>MT
Looks good.
<==

* Building on the previous point, there's probably something more
worth clarifying. Let's say that the client receives an
AS-to-Client response specifying "ace_profile" with value
"coap_dtls". Presumably, the following applies:
- The client can feel free to go ahead with TLS or DTLS as it
sees fit, if it does not know in advance which the RS prefers or
exclusively supports.
- Then, if the RS does not show support for DTLS (TLS), the
client may want to try again with TLS (DTLS) if supporting it.
On the other hand, a client or RS that has been registered to
the AS as supporting the "coap_dtls" profile is supposed to
support at least one among TLS or DTLS.
You are raising an interesting point. It might happen that the
client supports either DTLS or TLS, and the resource server has only
support for the other transport layer security, they might not be
able to talk to each other at all. The same might happen for other
values of 'ace_profile' but for different profiles, the
AS-to-clientn response would make this transparent.

Do you feel that we should elaborate on the case where ace_profile:
coap_dtls is returned in the AS-to-Client response but client and
resource server still will not be able to setup a (D)TLS connection?

==>MT
Yes, it would help to elaborate on that. As you say, there is a possibility of no commonly supported transport security protocol, although within the commonly supported profile.

In that case, and assuming that neither of the two parties can be (promptly) updated to broaden its support, the client would just have to give up after failing to establish a channel with the only transport security protocol it supports.


Thanks,
/Marco
<==

Done

Grüße
Olaf

--
Marco Tiloca
Ph.D., Senior Researcher

Division: Digital System
Department: Computer Science
Unit: Cybersecurity

RISE Research Institutes of Sweden
https://www.ri.se

Phone: +46 (0)70 60 46 501
Isafjordsgatan 22 / Kistagången 16
SE-164 40 Kista (Sweden)

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