Hi Roman,
Thank you very much for your detailed comments!
We addressed your comments with two exceptions as explained in detail
below. You can see most of the changes at
https://github.com/ace-wg/ace-dtls-profile/commit/a9ee40dff5093f1cf43e1b734eb6e02745f43f4d
On 3/23/21 4:32 AM, Roman Danyliw via Datatracker wrote:
> Roman Danyliw has entered the following ballot position for
> draft-ietf-ace-dtls-authorize-16: Discuss
>
> --
> DISCUSS:
> --
>
> (A simple editorial fix) Per Section 5.8.2 of
[I-D.ietf-ace-oauth-authz], the
> name of the parameter in the C-to-AS communication is “ace_profile” (not
> “profile”). The “ace_profile” parameter is mistakenly referenced as
“profile”
> in the following places:
>
> -- Section 3.2.1:
>The response MAY contain a "profile" parameter with the value
>"coap_dtls" to indicate that this profile MUST be used for
>communication between the client and the resource server.
>
> -- Section 3.3.1:
>If the
>profile parameter is present, it is set to "coap_dtls".
Okay, done.
>
>
> --
> COMMENT:
> --
> > Thank you to Russ Mundy for the SECDIR review, and thank you to the
authors for
> responding to it.
>
> ** Does this profile only cover part of the oauth-authz framework?
Section 3.3
> explicitly says “the use of introspection is out of scope for this
> specification.” It might be helpful to note in the introduction that this
> profile only covers C-to-AS and C-to-RS communication.
Fixed in introduction.
>
> ** Section 3.2.1 Figure 3, uses the “req_aud” parameter, but this was
renamed
> to “audience” in -20 of draft-ietf-ace-oauth-authz
Good catch! Fixed.
>
> ** Section 3.2.1. Per ‘The response MAY contain a "profile" parameter
with the
> value "coap_dtls" to indicate that this profile MUST be used for
communication
> between the client and the resource server’, this is true (see the DISCUSS
> above though). However, it might be worthwhile to point out that per
Section
> 5.8.2 of draft-ietf-ace-oauth-authz-38, this “MAY” is actually a MUST
if the
> request has an empty “ace_profile” parameter.
Okay, fixed.
>
> ** Section 3.2.2. Per “This specification therefore mandates
implementation
> support for curve25519 ...”, perhaps RFC2119 language should be used here
Okay, changed to MUST implement.
>
> ** Section 3.3.1. Per all of the text after “The method for how the
resource
> server determines the symmetric key from an access token containing
only a key
> identifier is application-specific; the remainder of this section
provides one
> example”, consider removing all of the RFC2119 language is this text
as its an
> example.
The Gen-ART review from Paul Kyzivat of 19 Jul 2020 suggested to include
the normative language to avoid ending up with unclear specifications.
(The normative language has been added in
https://github.com/ace-wg/ace-dtls-profile/commit/9ab383c0e08f8d4bff5335cbfadb1c6b48289472)
>
> ** Section 3.3.2. Per “When the resource server receives an access
token, it
> MUST check if the access token is still valid ...”, a reference to Section
> 5.10.1.1 of [I-D.ietf-ace-oauth-authz] for additional verification
procedures
> might be helpful
Fixed.
>
> ** Section 3.2.2. and 7:
>
> (a) Section 3.2.2.
>To be consistent with [RFC7252] which allows for shortened MAC tags
>in constrained environments, an implementation that supports the RPK
>mode of this profile MUST at least support the ciphersuite
>TLS_ECDHE_ECDSA_WITH_AES_128_CCM_8 [RFC7251].
>
> (b) As this specification aims at constrained devices and
>uses CoAP [RFC7252] as transfer protocol, at least the ciphersuite
>TLS_PSK_WITH_AES_128_CCM_8 [RFC6655] should be supported
>
> The text in (b) is weaker on the mandatory required of the
ciphersuite. In
> (b), likely s/should be supported/must be supported/.
We changed (b) to MUST support.
>
> ** Section 7. Per “For longer-lived access tokens, DHE ciphersuites
should be
> used”, perhaps add a parenthetical at the end of this sentence of “(i.e.,
> ciphersuites of the form TLS_DHE_PSK_*)”.
Fixed as suggested.
>
> ** Section 7.1. Session resumption is noted to be NOT RECOMMENDED.
Is there a
> reason this can’t be stronger (MUST NOT)?
Prohibiting session resumption would be too restrictive as this can be
useful for very constrained clients. We therefore changed it as follows:
OLD:
Therefore, the use of session resumption is NOT RECOMMENDED for
resource servers.
NEW:
Therefore, session resumption should be used only in combination with
reasonably short-lived PoP keys.
>
> ** Section 7.2. No issues with the guidance here. Is there anything DTLS
> specific that suggests that developers "SHOULD" avoid multiple access
tokens
> per
