Re: [MLS] John Scudder's No Objection on charter-ietf-mls-01-00: (with COMMENT)

[Sean Turner <[e-mail]>]

I took a stab at removing the intro.  We can review tomorrow:
https://github.com/mlswg/wg-materials/pull/16

spt

> On Jan 24, 2024, at 11:36, Sean Turner <[e-mail]> wrote:
> 
> HI! I will take a stab at addressing these changes in the GH repo and we can discuss tomorrow.
> 
> spt
> 
>> On Jan 4, 2024, at 11:23, John Scudder via Datatracker <[e-mail]> wrote:
>> 
>> John Scudder has entered the following ballot position for
>> charter-ietf-mls-01-00: No Objection
>> 
>> When responding, please keep the subject line intact and reply to all
>> email addresses included in the To and CC lines. (Feel free to cut this
>> introductory paragraph, however.)
>> 
>> 
>> 
>> The document, along with other ballot positions, can be found here:
>> https://datatracker.ietf.org/doc/charter-ietf-mls/
>> 
>> 
>> 
>> ----------------------------------------------------------------------
>> COMMENT:
>> ----------------------------------------------------------------------
>> 
>> My comments can be summed up as agreement with Éric’s "May I also suggest
>> to reduce the leading part of the charter about the history and achievements
>> of the MLS WG?”. If the history is to be kept (which I don't prefer,
>> even after reading Sean's reply, but wouldn't block on) then there are
>> a bunch of errors that need to be fixed, noted below. The easiest fix though,
>> would be to just remove the historical parts.
>> 
>>> The Messaging Layer Security (MLS) protocol, RFC 9420, specifies a key
>>> establishment protocol that provides efficient asynchronous group key
>>> establishment with forward secrecy (FS) and post-compromise security (PCS)
>>> for groups in size ranging from two to thousands.
>> 
>> Fine. But I think you could remove the bullet list of properties. Anyone
>> curious can go read the RFC, can't they?
>> 
>> But if the bullet list is retained, it needs a fix, noted below.
>> 
>>> 
>>> MLS has the following properties:
>>> 
>>> o Message Confidentiality - Messages can only be read
>>> by members of the group
>>> o Message Integrity and Authentication - Each message
>>> has been sent by an authenticated sender, and has
>>> not been tampered with
>>> o Membership Authentication - Each participant can verify
>>> the set of members in the group
>>> o Asynchronicity - Keys can be established without any
>>> two participants being online at the same time
>>> o Forward secrecy - Full compromise of a node at a point
>>> in time does not reveal past messages sent within the group
>>> o Post-compromise security - Full compromise of a node at a
>>> point in time does not reveal future messages sent within the group
>>> o Scalability - Resource requirements have good scaling in the
>>> size of the group (preferably sub-linear)
>> 
>> The parenthetical comment "(preferably sub-linear)" made sense in the
>> previous charter, but doesn't make any sense in describing the properties
>> of an approved protocol specification. Either delete the parenthetical,
>> or fix it.
>> 
>>> 
>>> It is not a goal of this group to enable interoperability/federation
>>> between messaging applications beyond the key establishment,
>>> authentication, and confidentiality services. Full interoperability
>>> would require alignment at many different layers beyond security,
>>> e.g., standard message transport and application semantics. The
>>> focus of this work is to develop a messaging security layer that
>>> different applications can adapt to their own needs.
>>> 
>>> While authentication is a key goal of this working group, it is not
>>> the objective of this working group to develop new authentication
>>> technologies. Rather, the MLS protocol provides a way to leverage
>>> existing authentication technologies to associate identities with
>>> keys used in the protocol, just as TLS does with X.509.
>> 
>> Again, I think the history lesson below seems surplus to requirements:
>> 
>>> 
>>> While developing the MLS protocol, the group drew on lessons learned
>>> from several prior message-oriented security protocols, in addition
>>> to the proprietary messaging security protocols deployed within
>>> existing applications:
>>> 
>>> o S/MIME - https://tools.ietf.org/html/rfc5751
>>> o OpenPGP - https://tools.ietf.org/html/rfc4880
>>> o Off the Record - https://otr.cypherpunks.ca/Protocol-v3-4.1.1.html
>>> o Double Ratchet - https://en.wikipedia.org/wiki/Double_Ratchet_Algorithm
>>> 
>>> The working group followed the pattern of TLS 1.3, with specification,
>>> implementation, and verification proceeding in parallel. When we arrived
>>> at RFC, we had several interoperable implementations as well as a thorough
>>> security analysis.
>> 
>> If you think it's important to say "this is how the WG wants to work" then
>> I suggest re-wording it in terms like that instead of "this is what we did
>> before" which doesn't say anything about expectations going forward.
>> 
>> The next paragraph doesn't make any sense because its context is material
>> from the old charter, that was deleted for this one:
>> 
>>> 
>>> Note that consensus is required both for changes to the protocol mechanisms
>>> from these documents and retention of the mechanisms from them. In particular,
>>> because something is in the initial document set does not imply that there is
>>> consensus around the feature or around how it is specified.
>> 
>> I think the above paragraph can be deleted, or if you think it has
>> a nugget in it that needs to be retained, it needs a rewrite.
>> 
>>> 
>>> Now that MLS has been published, the group will work on the following MLS
>>> protocol extensions:
>> 
>> You could drop "Now that MLS has been published" but whatever.
>> 
>>> 
>>> Support for use of MLS in protocols developed by the MIMI working group
>>> Support for new credential types
>>> Support for common operational patterns in messaging applications
>>> Support for quantum resistance
>>> Framework for safe extensibility
>>> Detection of lost application messages
>>> Support for sending messages to individual members of a group
>>> Many of extensions to support these features will be included in
>>> draft-ietf-mls-extensions, but some of the extensions will be published in
>>> seperate Internet-Drafts.
>>> 
>> 
>> The sentence above, parsed closely, seems to indicate you don't intend to
>> publish RFCs, just Internet Drafts. Probably s/Internet-Drafts/specifications/
>> I guess.
>> 
>> 
>> 
>