Re: [Ntp] The trick to timestamp with authentication

Doug Arnold <doug.arnold@meinberg-usa.com> Fri, 04 December 2020 01:03 UTC

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From: Doug Arnold <doug.arnold@meinberg-usa.com>
To: Hal Murray <hmurray@megapathdsl.net>
CC: NTP WG <ntp@ietf.org>
Thread-Topic: [Ntp] The trick to timestamp with authentication
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Date: Fri, 04 Dec 2020 01:03:16 +0000
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Subject: Re: [Ntp] The trick to timestamp with authentication
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I think that the enterprise networks of financial institutions, broadcast companies and power grids all want security and on path support.  Maybe large data centers as well. Broadcast and power have already adopted ptp and will probably stick with that, but my interactions with people in finance and data centers suggest that some of them would prefer a more precise version of ntp.  Some companies in finance are already doing nonstandard sub microsecond "ntp."  That is hardware timestamped ntp packets, but with higher than normal message rates and different client algorithms.  

The ntp working group could decide ntpv5 can support on path corrections or security, but not both.  However, I suspect a lot of people would be disappointed. 

Doug

On 12/3/20, 6:36 PM, "Hal Murray" <hmurray@megapathdsl.net> wrote:


    doug.arnold@meinberg-usa.com said:
    > This could be handled using a symmetric group key that authorized nodes get
    > periodically from a key exchange server.  See, for example GDOI.  I believe
    > that NTS could be adapted to group key operation as well. 

    The whole idea of patching an authenticated packet seems wrong.

    How much effort has gone into investigating alternatives?


    > I see you were paying attention. Accuracy and security are a trade-off.  If
    > you want on path timing support and security, then you either have to have a
    > lot of secrets or a secret that a lot of nodes are in on.  Either way it is
    > less secure than just NTS between a client and a server.  However, in a
    > private network where someone wants microsecond level time transfer accuracy
    > that might be a sensible trade-off. 

    That seems like a narrow market.  It's a private network.  They want 
    authentication so they don't trust their network yet they do trust it enough 
    to patch their authenticated packets.


    -- 
    These are my opinions.  I hate spam.