Subject: Re: [Dcrup] Ben Campbell's Yes on draft-ietf-dcrup-dkim-usage-04: (with COMMENT)

From: "Murray S. Kucherawy" <[email-masked]>
Date: Thu, 19 Oct 2017 00:35:31 -0700

Reducing distribution since this has been approved, but just to close the
issues raised by the IESG Review:

On Wed, Sep 27, 2017 at 7:10 PM, Ben Campbell <[email-masked]> wrote:

>
> ----------------------------------------------------------------------
> COMMENT:
> ----------------------------------------------------------------------
>
> -4: "Verifiers MUST verify using rsa-sha256."
>
> Should this say "...MUST be able to..."? That is, am I correct in assuming
> that
> a verifier will use the scheme specified by the signer if it is capable of
> doing so, and that it doesn't make sense to try to verify with rsa-sha256
> if
> the signer used something else?
>

I see Ben's point, and "MUST be able to..." sounds reasonable to me.  I
think this also addresses Jari's GEN-ART point (to which Mirja alluded),
and his "MUST implement" suggestion also seems reasonable to me.

What does the WG prefer?

-MSK

---

From: Martin Thomson <[email-masked]>
Date: Thu, 19 Oct 2017 19:40:18 +1100

On Thu, Oct 19, 2017 at 6:35 PM, Murray S. Kucherawy
<[email-masked]> wrote:
> think this also addresses Jari's GEN-ART point (to which Mirja alluded), and
> his "MUST implement" suggestion also seems reasonable to me.
>
> What does the WG prefer?

I saw the original requirement as stipulating a policy requirement in
addition to an implementation requirement.  That is, verifiers need to
insist on a valid rsa-sha256 signature or the message is considered
unverified.

---

From: Scott Kitterman <[email-masked]>
Date: Thu, 19 Oct 2017 10:49:26 +0000

>insist on a valid rsa-sha256 signature or the message is considered

That's what I was trying to communicate when I wrote it that way.

Scott K

---

From: "Salz, Rich" <[email-masked]>
Date: Thu, 19 Oct 2017 11:59:53 +0000

*   I see Ben's point, and "MUST be able to..." sounds reasonable to me

As an individual, I agree.

---

From: Kurt Andersen <[email-masked]>
Date: Thu, 19 Oct 2017 08:44:07 -0700

> and his "MUST implement" suggestion also seems reasonable to me.

"MUST be able to" seems to capture the intent.

--Kurt

---

From: Hector Santos <[email-masked]>
Date: Mon, 23 Oct 2017 22:54:25 -0400

> insist on a valid rsa-sha256 signature or the message is considered

+1, but I believe the policy requirement is the DKIM signer domain 
insisting via the public key record using a "h=sha256" tag.  The 
verifier should be ready to invalidate a DKIM sha1 signed message with 
a hash policy mismatch result/error. An SMTP Verifier spawning a 
dynamic DKIM-related protocol check at the DATA state can return a 
permanent negative response code, i.e. 55z.

-- 
HLS

---

From: "Murray S. Kucherawy" <[email-masked]>
Date: Tue, 24 Oct 2017 12:55:48 -0700

On Thu, Oct 19, 2017 at 8:44 AM, Kurt Andersen <[email-masked]> wrote:

> On Thu, Oct 19, 2017 at 12:35 AM, Murray S. Kucherawy <[email-masked]
> > wrote:
>
>>

I concur (as an individual).

And as chair, I'd say this small issue probably has consensus, so Scott,
please make this tweak and resubmit (modulo the other post-IESG thread) and
then Alexey can send it on its way.

-MSK

---

From: Scott Kitterman <[email-masked]>
Date: Wed, 25 Oct 2017 00:11:53 +0000

>then Alexey can send it on its way.

Will do once I know what to put in for the other thread.

Scott K