Subject: Re: [dmarc-ietf] Lenient DKIM (new Internet Draft)

From: Rick van Rein <[email-masked]>
Date: Wed, 04 Oct 2017 08:15:02 +0200

Hello,

Thanks to Scott for his feedback:

> Making DKIM signing MIME aware was specifically rejected during DKIM
> development due to implementation complexity.

I'm afraid I wasn't there, but would like to learn from the past.  Any
references are welcome.

But what exactly do you mean by "implementation complexity"?

 - the need to incorporate MIME-knowledge into an MTA (which one might
argue is not new -- but it is now a requirement for the signing and
verifying MTA, which may have gotten by without until now)

 - the added complexity during signing and verification (I would agree;
but argue that this reflects the complexity of the mail system, and ends
there; it will not grow without bounds)

 - the need for two passes during verification (I am working on that;
recognising an initial bit of text may be better than a rolling checksum
over the entire text)

 - ...?

I think the most important advantage of Lenient DKIM is that it avoids
that a choice made in one place invalidates existing, constructive
things taking place elsewhere.  ARC will not solve that discrepancy; it
imposes one administrator's choice onto others.  To me, that is the most
dire form of complexity (and a reason why people may hold back on
deploying DKIM; look at this email for example, probably being rewritten
to UTF-8 and thereby invalidating my DKIM-Signature made with dkimpy).

Anywhere I repeat things already said, please feel free to point me back
to discussions I've missed.

Thanks,
 -Rick

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From: Scott Kitterman <[email-masked]>
Date: Wed, 04 Oct 2017 10:09:42 +0000

It was the second.  I personally don't have time to hunt through decade old email archives.  That argument was made, but didn't carry the day.

Scott K