Re: [auth48] [IANA #1275931] [IANA] Re: AUTH48: RFC-to-be 9431 <draft-ietf-ace-mqtt-tls-profile-17> for your review

[Alanna Paloma <[e-mail]>]

Hi Amanda,

Thank you for completing those actions. The changes look good.

We have taken note of your comments regarding the “Profile registration” line and references for future documents.

Thank you, 
RFC Editor/ap 

> On Jul 3, 2023, at 6:11 PM, Amanda Baber via RT <[e-mail]> wrote:
> 
> Hi all,
> 
> We've completed what we could. See notes about references under item #3:
> 
>> 1) Please update the "application/ace+json" media type in the “Media
>> Types” registry <https://www.iana.org/assignments/media-types/> as
>> follows.
>> 
>> Old:
>> Applications that use this media type: This media type is intended
>> for authorization server-client and authorization server-resource
>> server communication as part of the ACE framework using JSON
>> encoding as specified in [RFC-ietf-ace-mqtt-tls-profile-17].
>> 
>> New:
>> Applications that use this media type:  This media type is intended
>> for Authorization-Server-Client and Authorization-Server-Resource-
>> Server communication as part of the ACE framework using JSON
>> encoding, as specified in RFC 9431.
> 
> This is done:
> 
> https://www.iana.org/assignments/media-types/application/ace+json
> 
>> Additionally, please add the following line:
>> Provisional registration? (standards tree only):  no
> 
> We were advised not to do this by the designated media type expert and author of RFC 6838 (see previous message). We discussed this before, and I believe it was decided that IANA would ask authors to remove the line.
> 
>> 2) Please remove the comma in the Description column of “mqtt_tls” in
>> the “ACE Profiles” registry
>> <https://www.iana.org/assignments/ace/ace.xhtml#ace-profiles> as
>> follows.
>> 
>> Old:
>> Description: Profile for delegating Client authentication and
>> authorization using MQTT for the Client and Broker (RS) interactions,
>> and HTTP for the AS interactions. TLS is used for confidentiality and
>> integrity protection and server authentication. Client authentication
>> can be provided either via TLS or using in-band PoP validation at the
>> MQTT application layer.
>> 
>> New:
>> Description: Profile for delegating Client authentication and
>> authorization using MQTT for the Client and Broker (RS) interactions
>> and HTTP for the AS interactions.  TLS is used for confidentiality and
>> integrity protection and server authentication.  Client authentication
>> can be provided either via TLS or using in-band PoP validation at the
>> MQTT application layer.
> 
> Done:
> https://www.iana.org/assignments/ace
> 
>> 3) In "Sub-Parameter Registry for application/aif+cbor and
>> application/aif+json” <https://www.iana.org/assignments/media-type-
>> sub-parameters/media-type-sub-parameters.xhtml>, please add a comma in
>> the Description/Specification column of "mqtt-topic-filter” and add
>> Section 2.3 to the Reference column as follows.
>> 
>> Old:
>> Description/Specification: Topic Filter as defined in [RFC-ietf-ace-
>> mqtt-tls-profile-17, Section 2.3].
>> Reference: [RFC-ietf-ace-mqtt-tls-profile-17]
>> 
>> New:
>> Description/Specification: Topic Filter, as defined in Section 2.3 of
>> RFC 9431.
>> Reference:  RFC 9431 (Section 2.3)
>> 
>> Additionally, please add “the” and capitalize “client” in the
>> Description/Specification column of "mqtt-permissions” and add Section
>> 2.3 to the Reference column as follows.
>> 
>> Old:
>> Description/Specification: Permissions for MQTT client as defined in
>> [RFC-ietf-ace-mqtt-tls-profile-17, Section 2.3]. Tperm is an array of
>> one or more text strings that each have a value of either "pub" or
>> "sub”.
>> Reference: [RFC-ietf-ace-mqtt-tls-profile-17]
>> 
>> New:
>> Description/Specification:  Permissions for the MQTT Client, as
>> defined in Section 2.3 of RFC 9431.  Tperm is an array of one or more
>> text strings that each have a value of either "pub" or "sub".
>> Reference:  RFC 9431 (Section 2.3)
> 
> The text changes are complete (https://www.iana.org/assignments/media-type-sub-parameters), and we've added the section numbers, but there are two issues with the requested reference changes:
> 
> 1) The draft strings need to remain in place until we can link to the published document
> 
> 2) Using the "RFC 9431 (Section 2.3)" format rather than our standard format is problematic. If you were to look at the XML, you'd see reference tags that look like this:
> 
> <xref type="rfc" data="rfc6533"/> - renders as "[RFC6533]"
> 
> <xref type="rfc" data="rfc6533">RFC6533, Section 6</xref> - renders as "[RFC6533, Section 6]"
> 
> <xref type="draft" data="RFC-ietf-ace-mqtt-tls-profile-17"/> - renders as "[RFC-ietf-ace-mqtt-tls-profile-17]"
> 
> <xref type="draft" data="RFC-ietf-ace-mqtt-tls-profile-17">RFC-ietf-ace-mqtt-tls-profile-17, Section 2.3</xref> - renders as "[RFC-ietf-ace-mqtt-tls-profile-17, Section 2.3]"
> 
> So any link will appear in brackets. We can present freeform text within it, like "[RFC 9431 (Section 2.3)]", but we have a strong preference for maintaining uniformity (in the "Reference" field) across the website, especially as we move from XML to database, and as we look at (programmatically) making references to sections actually link to those sections.
> 
> In general, reference fields in RFCs typically won't match the format used in the registries' "Reference" field. 
> 
> thanks,
> Amanda
> 
>> Best regards,
>> RFC Editor/ap
>> 
>>> On Jul 3, 2023, at 8:33 AM, Anthony Kirby <[e-mail]>
>>> wrote:
>>> 
>>> I approve this RFC for publication.  Many thanks, Anthony
>>> 
>>> On Mon, 3 Jul 2023, 11:16 Cigdem Sengul, <[e-mail]>
>>> wrote:
>>> Hello,
>>> Thank you for the revisions. I only have the following change:
>>> 2.2.5.  Broker Token Validation
>>> OLD: i.e., a CWT token uses COSE, while a JWT token uses JOSE.
>>> 
>>> NEW: i.e., a CWT  uses COSE, while a JWT uses JOSE.
>>> 
>>> The rest looks great, and after this minor edit, I approve this RFC
>>> for publication.
>>> Thank you very much for all your work.
>>> Kind regards,
>>> --Cigdem
>>> 
>>> 
>>> On Tue, 20 Jun 2023 at 22:56, Alanna Paloma <[e-mail]> wrote:
>>> Hi Cigdem,
>>> 
>>> Thank you for your reply.  We have updated as requested.
>>> 
>>> The files have been posted here (please refresh):
>>> https://www.rfc-editor.org/authors/rfc9431.xml
>>> https://www.rfc-editor.org/authors/rfc9431.txt
>>> https://www.rfc-editor.org/authors/rfc9431.html
>>> https://www.rfc-editor.org/authors/rfc9431.pdf
>>> 
>>> The relevant diff files have been posted here:
>>> https://www.rfc-editor.org/authors/rfc9431-diff.html (comprehensive
>>> diff)
>>> https://www.rfc-editor.org/authors/rfc9431-auth48diff.html (AUTH48
>>> changes)
>>> 
>>> Please review the document carefully and contact us with any further
>>> updates you may have.  Note that we do not make changes once a
>>> document is published as an RFC.
>>> 
>>> We will await approvals from each party listed on the AUTH48 status
>>> page below prior to moving this document forward in the publication
>>> process.
>>> 
>>> For the AUTH48 status of this document, please see:
>>> https://www.rfc-editor.org/auth48/rfc9431
>>> 
>>> Thank you,
>>> RFC Editor/ap
>>> 
>>> 
>>>> On Jun 20, 2023, at 8:34 AM, Cigdem Sengul
>>>> <[e-mail]> wrote:
>>>> 
>>>> 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
>>>> 
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>>>> 
>>>> 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
>>> 
> 
>