Re: [TLS] [POSSIBLE SPAM] Re: Asking the browser for a different certificate

Marsh Ray <marsh@extendedsubset.com> Tue, 30 March 2010 14:51 UTC

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Date: Tue, 30 Mar 2010 09:50:35 -0500
From: Marsh Ray <marsh@extendedsubset.com>
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To: "Kemp, David P." <DPKemp@missi.ncsc.mil>
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Subject: Re: [TLS] [POSSIBLE SPAM] Re: Asking the browser for a different certificate
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On 3/30/2010 9:24 AM, Kemp, David P. wrote:
> ADH is a pretty standard way of
> reducing ID exposure from an infinite number of attackers down to 1
> active party

It doesn't reduce it to one active party because Malloy can't know any
better than Alice or Bob if one of his connections is itself being MITM'd.

One could imagine amusing scenarios where AT&T and China bump into each
other on the wire and begin to argue "hey, buddy, go get your own
Facebook connection".

http://mashable.com/2010/01/16/att-facebook-error/
https://lists.dns-oarc.net/pipermail/dns-operations/2010-March/005260.html

> and 0 passive parties.  That's a fairly significant
> reduction.

Defeating passive eavesdropping is important, but it's sufficient in
general.

In the past, people were on shared Ethernet and would naturally be in a
position to quietly observe every packet going by.

For several common types of attacks today it's no harder to modify the
packets than it is to observe them. Think of China and Pakistan DNS- and
BGP-jacking YouTube for recent examples.

- Marsh