Subject: Re: DS Algorithm selection and SHA1 deprecation

From: Wes Hardaker <[email-masked]>
Date: Tue, 06 Dec 2005 15:00:01 -0800

>>>>> On Wed, 07 Dec 2005 08:44:51 +1100, Mark Andrews <[email-masked]> said:

Mark> For what it is worth, in implementing this draft, I found the
Mark> word "prefer" to be very poorly defined.  So much so the code
Mark> needed to be commented to make the intent clear.

How about changing:

   Validator implementations MUST be able to prefer DS records
   containing SHA-256 digests over those containing SHA-1 digests.

to:

   Validator implementations MUST be able to ignore DS RRs containing
   SHA-1 digests when a DS RR record exists with a SHA-256 digest and
   covers the same name.

??

Mark> At this stage I have no intention of implementing the MAY.

Such is the beauty or ugliness of a MAY depending on your
prospective.

-- 
Wes Hardaker
Sparta, Inc.

--
to unsubscribe send a message to [email-masked] with
the word 'unsubscribe' in a single line as the message text body.
archive: <http://ops.ietf.org/lists/namedroppers/>

---

From: Mark Andrews <[email-masked]>
Date: Wed, 07 Dec 2005 10:25:41 +1100

>    SHA-1 digests when a DS RR record exists with a SHA-256 digest and

	Validator implementations MUST, by default, ignore DS RRs containing
	SHA-1 digests if DS RRs with SHA-256 digests are present in the
	DS RRset.

--
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: [email-masked]

---

From: Mark Andrews <[email-masked]>
Date: Wed, 07 Dec 2005 12:09:28 +1100

Because zone administrators can not control the deployment support of
   SHA-256 in deployed validators that may referencing any given zone,
   deployments should consider publishing both SHA-1 and SHA-256 based
   DS records for a while.  Whether to publish both digest types
   together and for how long is a policy decision that extends beyond
   the scope of this document.

	I think this needs to be strengthend.  This currently allows
	you to use SHA-1 for one algorithm and SHA-256 for a different
	algorithm.  This really needs to be made pair-wise.  If you
	choose to publish both then you need to do this for every
	DNSKEY you are generating a DS for.

---

From: "william(at)elan.net" <[email-masked]>
Date: Tue, 6 Dec 2005 18:00:31 -0800 (PST)

>   SHA-1 digests when a DS RR record exists with a SHA-256 digest and

Is this glass-half-full<=>glass-half-empty kind of changes?

I really don't see a difference between these two paragraphs as far
as how implimentation would work...

Also is "MUST be able to" intentional (i.e. instead of just "MUST")?

-- 
William Leibzon
Elan Networks
[email-masked]

---

From: Wes Hardaker <[email-masked]>
Date: Tue, 06 Dec 2005 20:26:35 -0800

>>>>> On Tue, 6 Dec 2005 18:00:31 -0800 (PST), "william(at)elan.net" <[email-masked]> said:

>> SHA-1 digests when a DS RR record exists with a SHA-256 digest and

william> Is this glass-half-full<=>glass-half-empty kind of changes?

Yes.  It's almost entirely wording nits that people have been talking
about, not about the concepts underneath.

william> I really don't see a difference between these two paragraphs as far
william> as how implimentation would work...

There isn't any.  Mark was stating that the wording wasn't clear in
his mind.  It obviously was in yours if you read it the same way both
times.  :-)

william> Also is "MUST be able to" intentional (i.e. instead of just "MUST")?

Yes.  Because it doesn't mandate policy, it only mandates that it must
be possible to ignore SHA-1 in the presence of SHA-256 but allows for
implementations to accept operator configuration that requires other policy.

-- 
Wes Hardaker
Sparta, Inc.