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Re: [tsvwg] design assumptions - draft-ietf-udp-options

Derek Fawcus <dfawcus+lists-tsvwg@employees.org> Wed, 17 July 2019 21:22 UTC

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Date: Wed, 17 Jul 2019 22:22:20 +0100
From: Derek Fawcus <dfawcus+lists-tsvwg@employees.org>
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Subject: Re: [tsvwg] design assumptions - draft-ietf-udp-options
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On Wed, Jul 17, 2019 at 02:04:49PM -0700, C. M. Heard wrote:
> On Wed, Jul 17, 2019 at 12:16 PM Joe Touch <touch@strayalpha.com> wrote:
> 
> > And no, doing security, integrity checks, etc., on fragments is not the
> > same as doing it over the reassembled whole.
> >
> 
> But that's EXACTLY how TCP works -- both TCP checksums and TCP-AO
> cover *individual segments*.

It is also a lesson which has been hard learnt in the various crypto
protocols.  We should authenticate (and encrypt) individual packets.

Which I suggest in this case means authenticate the UDP fragments.

As to ACS, I'm not sure.  I belive to date it has been defined to be
over the reassembled fragment.

DF

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