Re: [tcpinc] Adam Roach's Yes on draft-ietf-tcpinc-tcpcrypt-09: (with COMMENT)

Kyle Rose <krose@krose.org> Thu, 09 November 2017 14:16 UTC

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From: Kyle Rose <krose@krose.org>
Date: Thu, 9 Nov 2017 22:16:00 +0800
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To: Adam Roach <adam@nostrum.com>
Cc: "Mirja Kuehlewind (IETF)" <ietf@kuehlewind.net>, The IESG <iesg@ietf.org>, tcpinc <tcpinc@ietf.org>, tcpinc-chairs@ietf.org, draft-ietf-tcpinc-tcpcrypt@ietf.org
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Subject: Re: [tcpinc] Adam Roach's Yes on draft-ietf-tcpinc-tcpcrypt-09: (with COMMENT)
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On Thu, Nov 9, 2017 at 10:11 AM, Adam Roach <adam@nostrum.com> wrote:
> On 11/8/17 19:45, Mirja Kuehlewind (IETF) wrote:
> > That’s not true. This is to cover the case where the packet got corrupted on
> > the path, thus hopefully the retransmission will decrypt correctly.
>
> So, to be clear, you're talking about packet corruption that happens to
> produce a valid checksum, right? If that's the reasoning here, the authors
> probably want to include that rationale in the document.

Mirja's is my interpretation, as well.

Off-path attackers wouldn't be able to sent segments with the right
sequence number with high probability, so it's unlikely that this is a
DoS vector; but giving implementations the option of simply dropping
segments for which the authenticity check fails is not likely to cause
recurring timeout problems for correct implementations.

Kyle