I believe that Richard has done a fair job at responding in a way that I’d like 
to append a “+1” to it so that (absent voting) it can be counted as some sort 
of nod that “yes, there’s someone who agrees with the general sentiment.”

- Trent


From: Richard Clayton <rich...@highwayman.com>
Date: Saturday, January 25, 2025 at 11:12 AM
To: Ietf-dkim@ietf.org <Ietf-dkim@ietf.org>
Subject: [Ietf-dkim] Re: Charter #4?
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<09ee9385-c706-42b8-945f-360148d3bf88@ dcrocker. net>, Dave Crocker <dhc@ 
dcrocker. net> writes >A basic problem, throughout this entire discussion, has 
been the effort to treat


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In message <09ee9385-c706-42b8-945f-360148d3b...@dcrocker.net>, Dave

Crocker <d...@dcrocker.net> writes



>A basic problem, throughout this entire discussion, has been the effort to 
>treat

>simple relaying through MTAs, and a multiple-posting/delivering forwarding

>sequence such as with mailing lists, as the same thing.

>

>They aren't and never have been.

>

>Treating them the same is a fundamental architectural change, at best  The 
>above

>language hides this reality.

>

>Mailing lists managers are not MTAs. Not architecturally, not as software, and

>not operationally.



The proposed DKIM2 design does not treat them the same ... but it

recognises that there are two issues that arise when email is handled by

an intermediary ... the first is that one incoming email may result in

<N> outgoing emails which may or may not be the same as each other, and

secondly that the intermediary may alter the email in such a way that an

existing DKIM1 signature no longer validates.



Note that mailing lists generally explode and alter and relayers

generally do not explode and do not alter. Nevertheless some relayers

will explode (to "distribution lists") and some relayers may alter

(changing the Subject header field to contain [EXTERNAL] for example).

Equally some mailing lists have a single subscriber and some don't break

DKIM1 signatures.



I don't think how a mailing list manager is implemented affects this

(you could make a simple one by a suitable Exim config) so it might be

an MTA after all.



>> or evaluation of the content for any sort of validity or safety.

>

>I have no idea what providing for evaluation of the content for validity or

>safety means.  Nor, I believe, is there any widespread history of discussion of

>that, in those terms.

>

>I suggest breaking this point out and writing something very different, to set

>up the concern.  (I don't understand the am not sufficiently clear about what 
>is

>intended here to be able to draft possible wording.)



This part of the charter is I assume meant to put assessing the safety

of an intermediaries change out of scope -- the proposed DKIM2 design

merely records what the change was and provides a robust way of knowing

which entity made it (so that one might hang some reputation on that

entity in an out-of-scope manner).



>> Still, there exist known shortcomings in the email model that DKIM

>> alone is not designed to address, including the following:

>

>There are additional needs.  They are new.  Or, at least, they were not

>previously a priority.  Since they were not needs when DKIM was developed, they

>are not 'shortcomings'.



they may not have been perceived to be shortcomings then -- they are

now, which is why a number of people wish to improve things for the

people whose email they handle



>> The working group will observe the success of current technologies,

>> primarily DKIM, reusing its techniques where applicable, to develop a

>> new technology suite that seeks to address these concerns.  Early

>> experience from the deployment of ARC [RFC 8617] will also be

>> considered.  In particular, this technology will:

>

>Rather:

>

>   The working group will pursue incremental enhancements to DKIM

>   and/or DKIM use, where possible.  It will pursue parallel or

>   replacement mechanisms only where incremental change is not feasible.



this is recipe for spending a considerable amount of time arguing about

exotic changes to existing fields and will result in complex and hard to

maintain code that has to handle two (or more) interpretations of header

fields in parallel. This heats up the planet to no purpose (let alone

heating up the tempers of WG participants)



if the engineers (including myself) who have been debating these issues

(for most of a year now) thought that simple mods to DKIM1 were a good

way forward that is what we would have proposed.



>> * Provide stronger assurances against unauthorized use of the

>> (envelope) sender, reducing the success of direct domain name misuse

>> and improving the value of delivery status notifications;

>

>The concept of authorized use of the Mail From exists in SPF and nowhere else.

>As such, the premise of this objective is problematic.



I think the text in the charter is meant to nod towards the DKIM2 notion

that DSNs should not be sent to the envelope sender but "back along the

chain" and hence various mangling of MAIL FROM that is used to direct

DSNs to an appropriate entity will no longer be required



>> * Identify message mutations made by any handling agent; and

>

>I suspect this means identification of common mutations, rather than all

>mutations, since there is no limit to the latter. This text needs elaboration,

>for clarity and precision.



I didn't think "clarity and precision" were required for a charter,

merely an indication of what was or was not in scope. Identifying all

mutations is clearly in scope ... being able to "undo" them may be too

complicated to consider (and self-defeating --- an intermediary that

redacts sensitive information or removes malicious attachments will not

wish a recipient to be able to undo their changes)



>> The working group will strongly prefer output that, when deployed,

>> does not disturb the deployed ecosystem.

>

>Given the presumption of DKIM replacement, this sentence is surprising.  With

>the incremental approach I'm advocating, it might be reasonable to retain.

>

>> It may, however, through the normal course of evolution, replace

>> technologies such as DKIM and ARC.

>

>The draft specification this work is currently based on requires replacement.



you can DKIM1 and DKIM2 sign in parallel if you wish  (and SPF will

continue to be "a thing" whilst there is continued toleration of dumb

devices such as security cameras sending direct to a destination

mailbox).



In the fullness of time, I doubt that larger mailbox providers will care

much about the DKIM1 signature and it may be that security cameras

cannot be configured as they are today.



- --

richard                                                   Richard Clayton



Those who would give up essential Liberty, to purchase a little temporary

Safety, deserve neither Liberty nor Safety. Benjamin Franklin 11 Nov 1755



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