Subject: [ntpwg] NTS: DTLS and symmetric mode

From: Harlan Stenn <[email-masked]>
Date: Mon, 31 Jul 2017 10:47:25 -0700

A topic that came up on our NTS implementation call has to do with DTLS.

I hope I communicate the following well enough.

Dave Mills recalls seeing a message where it was stated that DTLS is
great for client/server associations, but DTLS was not an
efficient/effective/whatever way to establish a symmetric association.

Thoughts or comments?
-- 
Harlan Stenn <[email-masked]>
http://networktimefoundation.org - be a member!
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From: Daniel Franke <[email-masked]>
Date: Mon, 31 Jul 2017 14:26:57 -0400

On Jul 31, 2017 1:47 PM, "Harlan Stenn" <[email-masked]> wrote:

I recall you asserting this in Prague but I haven't seen said message or
anything else which would substantiate this claim. Do you have details?
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From: Harlan Stenn <[email-masked]>
Date: Mon, 31 Jul 2017 11:30:56 -0700

> anything else which would substantiate this claim. Do you have details?

No, which is why I'm asking the question.

Is DTLS well-suited for symmetric associations, which require mutual
authentication?

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From: Job Snijders <[email-masked]>
Date: Mon, 31 Jul 2017 20:36:36 +0200

On Mon, Jul 31, 2017 at 02:26:57PM -0400, Daniel Franke wrote:
> I recall you asserting this in Prague but I haven't seen said message
> or > anything else which would substantiate this claim. Do you have
> details?

And how would it compare to QUIC?

If QUIC has been discussed before, I'd appreciate pointers to the
appropiate archive URLs.

Kind regards,

Job

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From: Aanchal Malhotra <[email-masked]>
Date: Mon, 31 Jul 2017 20:50:56 +0200

> If QUIC has been discussed before, I'd appreciate pointers to the

We never discussed NTP over QUIC, partly because it is still a draft and
not an IETF standard. But also because it does not have any implementation
yet except for the one by google which is specifically for HTTP. Standard
crypto libraries of course do not support it yet. So there will be
deployment issues for NTP.

Having said that, I still feel it is worth having a discussion on if we can
do NTP over QUIC, given that it is specifically designed to provide low
latency for connection establishment and transport (which is exactly what
we need.) But there may be other caveats?

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From: Daniel Franke <[email-masked]>
Date: Mon, 31 Jul 2017 14:59:30 -0400

> Is DTLS well-suited for symmetric associations, which require mutual

Yes. DTLS supports mutual authentication through the use of client
certificates or pre-shared keys.
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