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Re: [ntpwg] Antw: Re: Antw: Re: call for adoption (draft-dfranke-ntp-data-minimization)

Daniel Franke <dfoxfranke@gmail.com> Tue, 28 March 2017 14:08 UTC

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From: Daniel Franke <dfoxfranke@gmail.com>
Date: Tue, 28 Mar 2017 10:08:16 -0400
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To: Ulrich Windl <Ulrich.Windl@rz.uni-regensburg.de>
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Subject: Re: [ntpwg] Antw: Re: Antw: Re: call for adoption (draft-dfranke-ntp-data-minimization)
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On 3/28/17, Ulrich Windl <Ulrich.Windl@rz.uni-regensburg.de> wrote:
> IMHO it would be consistent to set precision to 3 (the lowest possible
> precision (0.125s) where NTP will start to work) and use 29 bits of
> randomness then. Still a half billion attack packets might transit without
> being detected, but I doubt that.

2**29 packets is about 541 gigabits including ethernet headers, so on
a 1Gbps link is about a 0.18% chance of attacker success during the 1s
MAXDIST window. On a 10Gbps link this becomes 1.8%. That's a big
improvement over the status quo but still a non-negligible weakness.

What's the benefit of randomizing anything less than the full 64 bits?
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