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Re: /dev/random is probably not
From: ChayoteMu <chayotemu () gmail com>
Date: Tue, 5 Jul 2005 16:25:11 -0700

It's not necessarily the traffic itself, but aspects of the traffic.
Someone had mentioned that the timing between recieving the packets
was what's used, even if you see that it may change over the rest of
the wire and there's nothing to say that the system is using all the
traffic as the attacker sees it. Drop every 5th packet and hash the
result with the time and the attack doesn't have anything to work
with. Just because you can observe or control one aspect doesn't mean
you can observe/control the entire thing.

On 7/5/05, Glynn Clements <glynn () gclements plus com> wrote:

"Zow" Terry Brugger wrote:

It's been a while since I looked at the /dev/random design on Linux
(probably the early 2.4 days), however one thing that was quite
clear was that they did not use any network I/O as entropy sources
because an attacker, particularly one that already had control of
other machines on the same LAN segment, could have a high degree of
control over that source.

They don't need to have any control; simply being able to observe
network traffic means that it is no longer random (in the sense of
"unpredictable", which is what counts from a security perspective).

Glynn Clements <glynn () gclements plus com>

"To catch a thief, think like a thief. To catch a master thief, be a
master thief."

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