NTS keys as I understand them

[Gary E. Miller]

Yo Hal!

On Mon, 14 Jan 2019 12:58:00 -0800
Hal Murray via devel <devel at ntpsec.org> wrote:

> > Why would a client waste all is cookies at once?  Since they can be
> > reused until the NTPD returns a NACK this seems to ddefeat the
> > benefit of keeping spare cookies around.   
> 
> To avoid bad-guys tracking you when you change IP Addresses.

How does using all your cookies at once, at startup, prevent this?

> The NTP client gets a new cookie with each response.  If things are
> working normally, you will never get a NACK or need to run NTS-KE
> again.  "normally" means fewer than 8 lost packets in a row.

Yes, but then you have no spare cookies for when you DO lose 8 packets
in a row.  It is pretty common to lose 8 packets in a row on today's
internet.

> It might make sense to use the same cookie on all packets in a burst,
> but then we have to think about switching IP Addresses in the middle
> of a burst and I don't want to go there.

How does a client even know that its IP changed?  What with NAT, CGNAT,
4in6, and other schemes in common use that is no longer possible.

RGDS
GARY
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Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
	gem at rellim.com  Tel:+1 541 382 8588

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