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Re: Binary packet protocol rethink

nisse@lysator.liu.se (Niels Möller ) Mon, 30 November 2015 08:02 UTC

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From: nisse@lysator.liu.se
To: Peter Gutmann <pgut001@cs.auckland.ac.nz>
Cc: Damien Miller <djm@mindrot.org>, Simon Tatham <anakin@pobox.com>, Simon Josefsson <simon@josefsson.org>, "ietf-ssh@netbsd.org" <ietf-ssh@netbsd.org>
Subject: Re: Binary packet protocol rethink
References: <87egfdxebo.fsf@latte.josefsson.org> <87egfdxebo.fsf@latte.josefsson.org> <nny4dksr3i.fsf@armitage.lysator.liu.se> <1448554180-sup-7145@atreus.tartarus.org> <9A043F3CF02CD34C8E74AC1594475C73F4B857C7@uxcn10-5.UoA.auckland.ac.nz> <alpine.BSO.2.20.1511292228450.12629@natsu.mindrot.org> <9A043F3CF02CD34C8E74AC1594475C73F4B92EF0@uxcn10-5.UoA.auckland.ac.nz>
Date: Mon, 30 Nov 2015 09:01:49 +0100
In-Reply-To: <9A043F3CF02CD34C8E74AC1594475C73F4B92EF0@uxcn10-5.UoA.auckland.ac.nz> (Peter Gutmann's message of "Mon, 30 Nov 2015 01:57:28 +0000")
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Peter Gutmann <pgut001@cs.auckland.ac.nz> writes:

>   You get traffic analysis resistance by, for example, breaking data into 
>   fixed-length packets, using cover traffic, and messing with packet 
>   timings, not by encrypting TLS headers.

One can do all of these with the current ssh wire protocol. It's even
straight-forward to do. But if we switch to clear text lengths (with no
other, deeper, changes to the protocol), it gets a lot more difficult.

So encrypted packet lengths aren't a solution, but they're a
*prerequisite* for the more serious counter measures.

Regards,
/Niels

-- 
Niels Möller. PGP-encrypted email is preferred. Keyid C0B98E26.
Internet email is subject to wholesale government surveillance.

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