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To: Ben Laurie <benl@freebsd.org>
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From: Mark Murray <mark@grondar.org>
From: Mark Murray <markm@FreeBSD.org>
Date: Fri, 14 Sep 2012 20:06:02 +0100
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Cc: Arthur Mesh <arthurmesh@gmail.com>,
	Ian Lepore <freebsd@damnhippie.dyndns.org>,
	Doug Barton <dougb@freebsd.org>, freebsd-security@freebsd.org,
	RW <rwmaillists@googlemail.com>, "Bjoern A. Zeeb" <bz@freebsd.org>
Subject: Re: svn commit: r239569 - head/etc/rc.d
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Ben Laurie writes:
> > I'll send patches (untested) in a couple of hours for discussion.
> 
> I used to like this idea, but it can break pretty badly if you repeat
> input, so in the end I decided hashes were the only safe way.

What??! Have you seen how Yarrow does its harvesting??

Presupposing there is no other source of randomness to get swamped out of the way,

$ cat /dev/zero > /dev/random  # pretend that /dev/zero is finite length.

... is harmless, and actually adds a small bit of perturbation to the entropy.

Please explain how repeating input can "break" things here?

M
--
Mark R V Murray
Pi: 132511160