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Re: [Ntp] Post NTS, Is shared key authentication interesting?

Watson Ladd <watsonbladd@gmail.com> Tue, 26 May 2020 14:55 UTC

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From: Watson Ladd <watsonbladd@gmail.com>
Date: Tue, 26 May 2020 10:55:41 -0400
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To: Daniel Franke <dfoxfranke@gmail.com>
Cc: Miroslav Lichvar <mlichvar@redhat.com>, NTP WG <ntp@ietf.org>
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Subject: Re: [Ntp] Post NTS, Is shared key authentication interesting?
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On Mon, May 25, 2020 at 9:29 AM Daniel Franke <dfoxfranke@gmail.com> wrote:
>
> Yes, shared-key authentication is still interesting.
>
> Putting the MAC in an extension field is clearly how NTPv4 should have done things from the start, but I don't see any benefit in changing until the legacy MAC field can be killed off entirely. So I would rather just pursue this as part of NTPv5 than adopt a MAC EF draft for NTPv4.
>
> I would like NTPv5's shared key authentication to be a little more closely integrated with NTS. Either accomplish it by doing a PSK TLS handshake for NTS-KE, or skip NTS-KE and have pre-shared S2C/C2S keys and a shorter cookie giving just a key ID.

I think PSK TLS is a better idea: all the complexity gets dumped on
the TLS stack, while the NTP specific parts don't change.


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