Re: [auth48] AUTH48: RFC-to-be 9431 <draft-ietf-ace-mqtt-tls-profile-17> for your review

[Cigdem Sengul <[e-mail]>]

Thank you for your email. Please see my responses below.
--Cigdem

On Tue, 20 Jun 2023 at 00:00, <[e-mail]> wrote:

> Authors,
>
> While reviewing this document during AUTH48, please resolve (as necessary)
> the following
> questions, which are also in the XML file.
>
> 1) <!--[rfced] To avoid awkward hyphenation, may we update the title as
> follows?
>
> Original:
> Message Queuing Telemetry Transport (MQTT)-TLS profile of Authentication
> and Authorization for Constrained Environments (ACE) Framework
>
> Perhaps:
> Message Queuing Telemetry Transport (MQTT) and TLS Profile for the
> Authentication and Authorization for Constrained Environments (ACE)
> Framework
> -->
>

I suggest:

Message Queuing Telemetry Transport (MQTT) and Transport Layer Security
(TLS) profile of Authentication
and Authorization for Constrained Environments (ACE) Framework


>
>
> 2) <!-- [rfced] Please insert any keywords (beyond those that appear in the
> title) for use on https://www.rfc-editor.org/search. -->
>

publish-subscribe, authorization information format


>
>
> 3) <!--[rfced] Please clarify; how does "and setting up the keying
> material"
> relate to the rest of the sentence? Is it a second topic for which
> assumptions are made? Or, should "and" be "while"?
>
> Original:
>    This document makes the same assumptions as Section 4 of the ACE
>    framework [I-D.ietf-ace-oauth-authz] regarding Client and RS
>    registration with the AS and setting up the keying material.
>
> Perhaps:
>    This document makes the same assumptions as Section 4 of the ACE
>    framework [RFC9200] regarding Client and RS registration with the AS
>    and regarding the setup of the keying material.
> -->
>
>
Suggested:
This document makes the same assumptions as Section 4 of the ACE
   framework [RFC9200] regarding Client and RS registration with the AS
   for setting up the keying material.


>
> 4) <!--[rfced] Should this instance of "JWT token" be updated to read
> simply as "JWT" to
> avoid redundancy (if expanded, "JWT token" would read "JSON Web Token
> token")?
>
> Original:
>   A JWT token uses JOSE, while a CWT token uses COSE
>   [RFC8152] for security protection.
>
> Perhaps:
>   A JWT uses JOSE, while a CWT token uses COSE
>   [RFC8152] for security protection.
>

Suggested (as the same argument applies to CWT):
 A JWT uses JOSE, while a CWT uses COSE
  [RFC8152] for security protection.



> Similarly, should "PSK key be updated to "PSK" (if expanded, "PSK key"
> would read
> Pre-Shared Key key")?
>
> Original:
>    To use TLS 1.3 with pre-shared keys, the Client utilizes the PSK key
>    extension specified in [RFC8446] using the key conveyed in the "cnf"
>    parameter of the AS response.
>
> Perhaps:
>    To use TLS 1.3 with pre-shared keys, the Client utilizes the PSK
>    extension specified in [RFC8446] using the key conveyed in the "cnf"
>    parameter of the AS response.
> -->
>

Yes, accepting the suggestion.


>
>
> 5) <!--[rfced] As "confidentiality" is not a term listed in RFC 4949 but
> "data
> confidentiality" is listed, we have updated the list below accordingly.
> Please let us know if further updates are needed.
>
> Original:
>    Certain security-related terms such as "authentication",
>    "authorization", "confidentiality", "(data) integrity", "message
>
>    authentication code", and "verify" are taken from [RFC4949].
>
> Perhaps:
>    Certain security-related terms such as "authentication",
>    "authorization", "data confidentiality", "(data) integrity", "message
>
>    authentication code", and "verify" are taken from [RFC4949].
> -->
>

Yes, accepting the suggestion.


>
>
> 6) <!--[rfced] Please clarify; what does "labeled with their topics"
> refer to?
>
> Original:
>    The Clients are MQTT Clients, which connect to the
>    Broker to publish and subscribe to Application Messages, labelled
>    with their topics.
>
> Perhaps (if the Clients are labeled):
>    The Clients are MQTT Clients, which connect to the
>    Broker to publish and subscribe to Application Messages, and are labeled
>    with their topics.
>
> Or (if the Application Messages are labeled):
>    The Clients are MQTT Clients, which connect to the
>    Broker to publish and subscribe to Application Messages (which are
>    labeled with their topics).
> -->
>

The Or version is correct version and accepted: the Application Messages
are labeled.
(This was written like this because MQTT v5 standard defines *Topic Name as*

The label attached to an Application Message which is matched against the
Subscriptions known to the Server.)

>
>
> 7) <!--[rfced] Should "Connection" be "Network Connection"?
>
> Original:
>   If the Network
>   Connection is closed without the Client first sending a
>   DISCONNECT packet with Reason Code 0x00 (Normal
>   disconnection) and the Connection has a Will Message, the
>   Will Message is published.
>
> Perhaps:
>   If the Network
>   Connection is closed without the Client first sending a
>   DISCONNECT packet with reason code 0x00 (Normal
>   disconnection) and the Network Connection has a Will Message, the
>   Will Message is published.
> -->
>

It should remain as original.
This was taken from MQTT v5 document: "If the Network Connection is closed
without the Client first sending a DISCONNECT packet with Reason Code 0x00
(Normal disconnection) and the Connection has a Will Message, the Will
Message is published".
The second "Connection" refers to MQTT Connection.

Perhaps if unclear:
  If the Network Connection is closed without the Client first sending a
  DISCONNECT packet with reason code 0x00 (Normal
  disconnection) and the MQTT Connection has a Will Message, the
  Will Message is published.


>
>
> 8) <!--[rfced] Figure 1 has been widened slightly for readability;
> please review. Specifically, a single space was added after
> (C), (D), (E), and (F), which matches how (A) and (B) appear,
> and the second lines of labels were indented. The side-by-side diff
> file is here: https://www.rfc-editor.org/authors/rfc9431-rfcdiff.html
> -->
>

This is all good.


>
>
> 9) <!--[rfced] Regarding Figure 2, may "Len." be changed to "Len" to match
> other instances within this figure, or is this difference intentional?
> Also, will it be clear to readers how to read this diagram? Specifically,
> the "Authentication Method" and "Authentication Data" portions seem
> unclear.
> -->
>
>
Please change "Len." to "Len".
The figure is explained in  2.2.4.2.
Old:
To use AUTH, the Client MUST set the Authentication Method as a property of
a CONNECT packet by using the property identifier 21 (0x15). This is
followed by a UTF-8-encoded string containing the name of the
Authentication Method, which MUST be set to "ace". If the Broker does not
support this profile, it sends a CONNACK packet with reason code 0x8C (Bad
authentication method).

New:
Figure 2 shows the Authentication Method and Authentication Data fields
when the client authenticates using AUTH property. The Client MUST set the
Authentication Method as a property of a CONNECT packet by using the
property identifier 21 (0x15). This is followed by a UTF-8-encoded string
containing the name of the Authentication Method, which MUST be set to
"ace". If the Broker does not support this profile, it sends a CONNACK
packet with reason code 0x8C (Bad authentication method).



>
> 10) <!-- [rfced] Please review the "type" attribute of each sourcecode
> element
> in the XML file to ensure correctness. If the current list of preferred
> values for "type" (
> https://www.rfc-editor.org/materials/sourcecode-types.txt)
> does not contain an applicable type, then feel free to let us
> know. Also, it is acceptable to leave the "type" attribute not
> set.
>
> In addition, review each artwork element. Specifically,
> should any artwork element be tagged as sourcecode or another
> element?
>  -->
>

"cddl" type is correct for the artwork in Figure 8.

Fig 9 should be tagged with "sourcecode", with type "json".

There is no other artwork to be tagged as source code.


>
>
> 11) <!--[rfced] As "PINGREQ" is defined in Section 1.3, we have updated
> "PINGREQUEST" to "PINGREQ". Please let us know if further updates are
> needed.
>
> Original:
>   The Broker SHOULD check
>   for token expiration on receiving a PINGREQUEST.
>
> Current:
>   The Broker SHOULD check
>   for token expiration on receiving a PINGREQ packet.
> -->
>

Thank you.


>
>
> 12) <!--[rfced] Do you agree with these changes (added 'the', capitalized
> 'Client'
> to match usage within the document)? If so, we will ask IANA to update the
> description in the registry (
> https://www.iana.org/assignments/media-type-sub-parameters/)
> accordingly.
>
> Original: Permissions for MQTT client as defined in ...
>
> Current:  Permissions for the MQTT Client as defined in ...
> -->
>
> That is OK.

>
> 13) <!--[rfced] Please clarify the last part of this sentence;
> specifically,
> what does the "which" clause describe? Is it the transport tokens that
> the Broker may need to store until they expire?
>
> Original:
>    If the Broker supports the public
>    "authz-info" topic, described in Section 2.2.2, then this may be
>    vulnerable to a DDoS attack, where many Clients use the "authz-info"
>    public topic to transport tokens that are not meant to be used, and
>    which the Broker may need to store until the tokens expire.
>
> Perhaps:
>    If the Broker supports the public
>    "authz-info" topic, described in Section 2.2.2, then this may be
>    vulnerable to a DDoS attack, where many Clients use the "authz-info"
>    public topic to to transport tokens that are not meant to be used
>    and that the Broker may need to store until they expire.
> -->
>

Yes, it is the tokens that need to be stored. Accepting the suggestion.

>
>
> 14) <!--[rfced] RFC 7525 has been obsoleted by RFC 9325, and RFC 8152 has
> been
> obsoleted by RFC 9052. May these references be updated accordingly?
>
> RFC 7525 is cited once:
>    For TLS 1.2, however, a client
>    MUST support TLS_ECDHE_PSK_WITH_AES_128_GCM_SHA256 for PSKs [RFC8442]
>    and TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 for RPKs [RFC8422], as
>    recommended in [RFC7525] (and adjusted to be a PSK cipher suite as
>    appropriate).


> RFC 8152 is cited once:
>    A JWT token uses JOSE, while a CWT token uses COSE
>    [RFC8152] for security protection.
> -->
>
>
Yes, please.



> 15) <!-- [rfced] FYI, we have added expansions for the following
> abbreviations
> per Section 3.6 of RFC 7322 ("RFC Style Guide"). Please review each
> expansion in the document carefully to ensure correctness.
>
> Concise Binary Object Representation (CBOR)
> JSON Web Encryption (JWE)
> -->
>

Correct.

>
>
> 16) <!--[rfced] We have made the following terminology capitalized for
> consistency.
> Please review this occurrences carefully and let us know if further updates
> are necessary.
>
> Will
> Will Delay Interval
> Will Flag
> Will Message
> Will Properties
> Will Retain
> Will Topic
> Will QoS
> -->
>

All capitalizations are correct.

>
>
> 17) <!--[rfced] Throughout the text, the following terminology appears to
> be used inconsistently.
>
> a) We have updated to use the form on the right. Please let us know of any
> objections.
>
> Control Packet / control packet
> Fixed Header / fixed header
> password / Password
> Payload / payload
> username / Username
> Variable Header / variable header
>

"Control Packet", "Fixed Header", and "Variable Header" are capitalized in
the MQTTv5 specification and, therefore, were capitalised here. (Source:
https://docs.oasis-open.org/mqtt/mqtt/v5.0/mqtt-v5.0.html)

Password - capital is correct.

"Username" is "User Name" in MQTTv5, and would be good if we keep the same
field names exactly as the MQTT protocol specifies in their specification.
(I acknowledge that the original text did not do a consistent job of that).


> b) Please review the terms below and let us know if/how they may be made
> consistent.
>
> Session vs. session
> Subscription vs. subscription
> -->
>

For session, the following need to be capitalised:
Section 1.3
Old:
 A Subscription comprises a Topic Filter and a maximum QoS. A Subscription
is associated with a single session.
New:
  A Subscription comprises a Topic Filter and a maximum QoS. A Subscription
is associated with a single Session.

Section 2.2.4.1
Old: The Connect flags in the variable header specify the properties of the
MQTT session.
New: The Connect flags in the variable header specify the properties of the
MQTT Session.

Old: In MQTT v5.0, the Client signals a clean session (i.e., that the
session does not continue an existing session) by setting the Clean Start
flag to 1 in the CONNECT packet. In this profile, the Client SHOULD always
start with a clean session. The Broker MAY also signal that it does not
support session continuation by setting the Session Expiry Interval to 0 in
the CONNACK. If the Broker starts a clean session, the Broker MUST set the
Session Present flag to 0 in the CONNACK packet to signal this to the
Client.

New: In MQTT v5.0, the Client signals a new Session (i.e., that the Session
does not continue an existing Session) by setting the Clean Start flag to 1
in the CONNECT packet. In this profile, the Client SHOULD always start with
a new Session. The Broker MAY also signal that it does not support the
continuation of an existing Session by setting the Session Expiry Interval
to 0 in the CONNACK. If the Broker starts a new Session, the Broker MUST
set the Session Present flag to 0 in the CONNACK packet to signal this to
the Client.
--------
Old: The Broker MAY support session continuation, e.g., if the Broker
requires it for QoS reasons. In this case, if a CONNECT packet is received
with Clean Start set to 0 and there is a Session associated with the Client
Identifier, the Broker MUST resume communications with the Client based on
the state from the existing Session. In its response, the Broker MUST set
the Session Present flag to 1 in the CONNACK packet to signal session
continuation to the Client. The session state stored by the Client and the
Broker is described in Section 5.

New: The Broker MAY support continuing an existing Session, e.g., if the
Broker requires it for QoS reasons. In this case, if a CONNECT packet is
received with Clean Start set to 0, and there is a Session associated with
the Client Identifier, the Broker MUST resume communications with the
Client based on the state from the existing Session. In its response, the
Broker MUST set the Session Present flag to 1 in the CONNACK packet to
signal the continuation of an existing Session to the Client. The Session
State stored by the Client and the Broker is described in Section 5.

Old: When reconnecting to a Broker that supports session continuation, the
Client MUST still provide a token in addition to using the same Client
Identifier and setting the Clean Start to 0. The Broker MUST still perform
PoP validation on the provided token. If the token matches the stored
state, the Broker MAY skip introspecting a token-by-reference and use the
stored introspection result. The Broker MUST also verify the Client is
authorized to receive or send MQTT packets that are pending transmission.
When a Client connects with a long Session Expiry Interval, the Broker may
need to maintain the Client's MQTT session state after it disconnects for
an extended period. Brokers SHOULD implement administrative policies to
limit misuse.

New: When reconnecting to a Broker that supports continuing existing
Sessions, the Client MUST still provide a token in addition to using the
same Client Identifier and setting the Clean Start to 0. The Broker MUST
still perform PoP validation on the provided token. If the token matches
the stored state, the Broker MAY skip introspecting a token-by-reference
and use the stored introspection result. The Broker MUST also verify the
Client is authorized to receive or send MQTT packets that are pending
transmission. When a Client connects with a long Session Expiry Interval,
the Broker may need to maintain the Client's MQTT Session State after it
disconnects for an extended period. Brokers SHOULD implement administrative
policies to limit misuse.
------
Old: Note that, according to the MQTT standard, the Broker uses the Client
Identifier to identify the session state. In the case of a Client
Identifier collision, a Client may take over another Client's session.

New: Note that, according to the MQTT standard, the Broker uses the Client
Identifier to identify the Session State. In the case of a Client
Identifier collision, a Client may take over another Client's Session.
---------
Section 2.4.2
Old: If the Broker starts a new session, it MUST also set Session Present
to 0 in the CONNACK packet to signal a clean session to the Client.
Otherwise, it MUST set Session Present to 1.

New: If the Broker starts a new Session, it MUST also set Session Present
to 0 in the CONNACK packet to signal a new Session to the Client.
Otherwise, it MUST set Session Present to 1.

Section 5
Old: In the case of a Client DISCONNECT, if the Session Expiry Interval is
set to 0, the Broker doesn't maintain session state but MUST keep the
retained messages. If the Broker maintains session state, the state MAY
include the token and its introspection result (for reference tokens) in
addition to the MQTT session state. The MQTT session state is identified by
the Client Identifier and includes the following:

the Client subscription state,

New:
In the case of a Client DISCONNECT, if the Session Expiry Interval is set
to 0, the Broker doesn't store the Session State but MUST keep the retained
messages. If the Broker stores the Session State, the state MAY include the
token and its introspection result (for reference tokens) in addition to
the MQTT Session State. The MQTT Session State is identified by the Client
Identifier and includes the following:

the Client Subscriptions,
----
Old:
   * if the Session is currently not connected, the time at which the
Session will end and session state will be discarded.
The token/introspection state is not part of the MQTT session state, and
PoP validation is required for each new connection, regardless of whether
MQTT session continuation is used.

New:
* if the Session is currently not connected, the time at which the Session
will end and the Session State will be discarded.
The token/introspection state is not part of the MQTT Session State, and
PoP validation is required for each new connection, regardless of whether
existing MQTT Sessions are continued.

(Note that Session State is capitalised in MQTT Spec.)

Section 6.1
Old:  The Client SHOULD set the Clean flag to 1 to always start a new
session. If the Clean flag is set to 0, the Broker MUST resume
communications with the Client based on the state from the current Session
(as identified by the Client Identifier). If there is no Session associated
with the Client Identifier, the Broker MUST create a new session. The
Broker MUST set the Session Present flag in the CONNACK packet accordingly,
i.e., 0 to indicate a clean session to the Client and 1 to indicate session
continuation. The Broker MUST still perform PoP validation on the provided
Client token. MQTT v3.1.1 does not use a Session Expiry Interval, and the
Client expects that the Broker maintains the session state after it
disconnects. However, the stored session state can be discarded as a result
of administrator action or policies (e.g., defining an automated response
based on storage capabilities), and Brokers SHOULD implement administrative
policies to limit misuse.

New: The Client SHOULD set the Clean flag to 1 to always start a new
Session. If the Clean flag is set to 0, the Broker MUST resume
communications with the Client based on the state from the current Session
(as identified by the Client Identifier). If there is no Session associated
with the Client Identifier, the Broker MUST create a new Session. The
Broker MUST set the Session Present flag in the CONNACK packet accordingly,
i.e., 0 to indicate a new Session to the Client and 1 to indicate that the
existing Session is continued. The Broker MUST still perform PoP validation
on the provided Client token. MQTT v3.1.1 does not use a Session Expiry
Interval, and the Client expects that the Broker maintains the Session
State after it disconnects. However, the stored Session State can be
discarded as a result of administrator action or policies (e.g., defining
an automated response based on storage capabilities), and Brokers SHOULD
implement administrative policies to limit misuse.

Section 6.2
Old: Therefore, the Broker will disconnect on almost any error and may not
keep the session state, necessitating that clients make a greater effort to
ensure that tokens remain valid and do not attempt to publish to topics
that they do not have permissions for.

New: Therefore, the Broker will disconnect on almost any error and may not
keep the Session State, necessitating that clients make a greater effort to
ensure that tokens remain valid and do not attempt to publish to topics
that they do not have permissions for.

Section 8
Old: After the Broker validates an access token and accepts a connection
from a client, it caches the token to authorize a Client's publish and
subscribe requests in an ongoing session.

New: After the Broker validates an access token and accepts a connection
from a client, it caches the token to authorize a Client's publish and
subscribe requests in an ongoing Session.

Old: For MQTT v5.0, when a Client connects with a long Session Expiry
Interval, the Broker may need to maintain the Client's MQTT session state
after it disconnects for an extended period. For MQTT v3.1.1, the session
state may need to be stored indefinitely, as it does not have a Session
Expiry Interval feature. The Broker SHOULD implement administrative
policies to limit misuse of the session continuation by the Client.

New: For MQTT v5.0, when a Client connects with a long Session Expiry
Interval, the Broker may need to maintain the Client's MQTT Session State
after it disconnects for an extended period. For MQTT v3.1.1, the Session
State may need to be stored indefinitely, as it does not have a Session
Expiry Interval feature. The Broker SHOULD implement administrative
policies to limit misuse by the Client resulting from continuing existing
Sessions.

=====================================
All "subscription" instances are to be capitalised to "Subscription" with
the following exceptions, which suggest additional changes following MQTT
specification:

Section 3.2
Old: To forward PUBLISH packets to the subscribing Clients, the Broker
identifies all the subscribers that have valid matching topic subscriptions
to the Topic Name of the PUBLISH packet (i.e., the tokens are valid, and
token scopes allow a subscription to this particular Topic Name).

New: To forward PUBLISH packets to the subscribing Clients, the Broker
identifies all the subscribers that have valid matching Topic Subscriptions
to the Topic Name of the PUBLISH packet (i.e., the tokens are valid, and
token scopes allow a Subscription to this particular Topic Name).
---------------------
Section 3.3
Old: For example, if the Client sends a subscription request for topic
"a/b/*" and has a token that permits "a/*", this is a valid subscription
request, as "a/b/*" is a subset of "a/*". (The process is similar to a
Broker matching the Topic Name in a PUBLISH packet against the
Subscriptions known to the Server.)

New: For example, if the Client sends a SUBSCRIBE request for topic "a/b/*"
and has a token that permits "a/*", this is a valid SUBSCRIBE request, as
"a/b/*" is a subset of "a/*". (The process is similar to a Broker matching
the Topic Name in a PUBLISH packet against the Subscriptions known to the
Server.)
-------------------------------


>
>
> 18) <!-- [rfced] Please review the "Inclusive Language" portion of the
> online
> Style Guide <
> https://www.rfc-editor.org/styleguide/part2/#inclusive_language>
> and let us know if any changes are needed.
>
> Note that our script did not flag any words in particular, but this should
> still
> be reviewed as a best practice.
> -->
>

This was reviewed earlier, and no issues are expected.

Please let me know if i need to make further clarifications.
Kind regards,
--Cigdem

>
> On Jun 19, 2023, [e-mail] wrote:
>
> *****IMPORTANT*****
>
> Updated 2023/06/19
>
> RFC Author(s):
> --------------
>
> Instructions for Completing AUTH48
>
> Your document has now entered AUTH48.  Once it has been reviewed and
> approved by you and all coauthors, it will be published as an RFC.
> If an author is no longer available, there are several remedies
> available as listed in the FAQ (https://www.rfc-editor.org/faq/).
>
> You and you coauthors are responsible for engaging other parties
> (e.g., Contributors or Working Group) as necessary before providing
> your approval.
>
> Planning your review
> ---------------------
>
> Please review the following aspects of your document:
>
> *  RFC Editor questions
>
>   Please review and resolve any questions raised by the RFC Editor
>   that have been included in the XML file as comments marked as
>   follows:
>
>   <!-- [rfced] ... -->
>
>   These questions will also be sent in a subsequent email.
>
> *  Changes submitted by coauthors
>
>   Please ensure that you review any changes submitted by your
>   coauthors.  We assume that if you do not speak up that you
>   agree to changes submitted by your coauthors.
>
> *  Content
>
>   Please review the full content of the document, as this cannot
>   change once the RFC is published.  Please pay particular attention to:
>   - IANA considerations updates (if applicable)
>   - contact information
>   - references
>
> *  Copyright notices and legends
>
>   Please review the copyright notice and legends as defined in
>   RFC 5378 and the Trust Legal Provisions
>   (TLP – https://trustee.ietf.org/license-info/).
>
> *  Semantic markup
>
>   Please review the markup in the XML file to ensure that elements of
>   content are correctly tagged.  For example, ensure that <sourcecode>
>   and <artwork> are set correctly.  See details at
>   <https://authors.ietf.org/rfcxml-vocabulary>.
>
> *  Formatted output
>
>   Please review the PDF, HTML, and TXT files to ensure that the
>   formatted output, as generated from the markup in the XML file, is
>   reasonable.  Please note that the TXT will have formatting
>   limitations compared to the PDF and HTML.
>
>
> Submitting changes
> ------------------
>
> To submit changes, please reply to this email using ‘REPLY ALL’ as all
> the parties CCed on this message need to see your changes. The parties
> include:
>
>   *  your coauthors
>
>   *  [e-mail] (the RPC team)
>
>   *  other document participants, depending on the stream (e.g.,
>      IETF Stream participants are your working group chairs, the
>      responsible ADs, and the document shepherd).
>
>   *  [e-mail], which is a new archival mailing list
>      to preserve AUTH48 conversations; it is not an active discussion
>      list:
>
>     *  More info:
>
> https://mailarchive.ietf.org/arch/msg/ietf-announce/yb6lpIGh-4Q9l2USxIAe6P8O4Zc
>
>     *  The archive itself:
>        https://mailarchive.ietf.org/arch/browse/auth48archive/
>
>     *  Note: If only absolutely necessary, you may temporarily opt out
>        of the archiving of messages (e.g., to discuss a sensitive matter).
>        If needed, please add a note at the top of the message that you
>        have dropped the address. When the discussion is concluded,
>        [e-mail] will be re-added to the CC list and
>        its addition will be noted at the top of the message.
>
> You may submit your changes in one of two ways:
>
> An update to the provided XML file
> — OR —
> An explicit list of changes in this format
>
> Section # (or indicate Global)
>
> OLD:
> old text
>
> NEW:
> new text
>
> You do not need to reply with both an updated XML file and an explicit
> list of changes, as either form is sufficient.
>
> We will ask a stream manager to review and approve any changes that seem
> beyond editorial in nature, e.g., addition of new text, deletion of text,
> and technical changes.  Information about stream managers can be found in
> the FAQ.  Editorial changes do not require approval from a stream manager.
>
>
> Approving for publication
> --------------------------
>
> To approve your RFC for publication, please reply to this email stating
> that you approve this RFC for publication.  Please use ‘REPLY ALL’,
> as all the parties CCed on this message need to see your approval.
>
>
> Files
> -----
>
> The files are available here:
>   https://www.rfc-editor.org/authors/rfc9431.xml
>   https://www.rfc-editor.org/authors/rfc9431.html
>   https://www.rfc-editor.org/authors/rfc9431.pdf
>   https://www.rfc-editor.org/authors/rfc9431.txt
>
> Diff file of the text:
>   https://www.rfc-editor.org/authors/rfc9431-diff.html
>   https://www.rfc-editor.org/authors/rfc9431-rfcdiff.html (side by side)
>
> Diff of the XML:
>   https://www.rfc-editor.org/authors/rfc9431-xmldiff1.html
>
> The following files are provided to facilitate creation of your own
> diff files of the XML.
>
> Initial XMLv3 created using XMLv2 as input:
>   https://www.rfc-editor.org/authors/rfc9431.original.v2v3.xml
>
> XMLv3 file that is a best effort to capture v3-related format updates
> only:
>   https://www.rfc-editor.org/authors/rfc9431.form.xml
>
>
> Tracking progress
> -----------------
>
> The details of the AUTH48 status of your document are here:
>   https://www.rfc-editor.org/auth48/rfc9431
>
> Please let us know if you have any questions.
>
> Thank you for your cooperation,
>
> RFC Editor
>
> --------------------------------------
> RFC9431 (draft-ietf-ace-mqtt-tls-profile-17)
>
> Title            : Message Queuing Telemetry Transport (MQTT)-TLS profile
> of Authentication and Authorization for Constrained Environments (ACE)
> Framework
> Author(s)        : C. Sengul, A. Kirby
> WG Chair(s)      : Daniel Migault, Loganaden Velvindron
> Area Director(s) : Roman Danyliw, Paul Wouters
>