Re: Why does reading from /dev/urandom deplete entropy so much?

From: Jeff Garzik <jeff@garzik.org>
To: Theodore Tso <tytso@mit.edu>, Mike McGrath <mmcgrath@redhat.com>,
	Jon Masters <jonathan@jonmasters.org>,
	Matt Mackall <mpm@selenic.com>,
	Alan Cox <alan@lxorguk.ukuu.org.uk>, Ray Lee <ray@madrabbit.org>,
	Adrian Bunk <bunk@kernel.org>,
	Marc Haber <mh+linux-kernel@zugschlus.de>,
	linux-kernel@vger.kernel.org
Subject: Re: Why does reading from /dev/urandom deplete entropy so much?
Date: Sat, 08 Dec 2007 13:31:09 -0500	[thread overview]
Message-ID: <475AE2ED.3050700@garzik.org> (raw)
In-Reply-To: <20071208174908.GJ17037@thunk.org>

Theodore Tso wrote:
> On Sat, Dec 08, 2007 at 11:33:57AM -0600, Mike McGrath wrote:
>>> Huh?  What's the concern?  All you are submitting is a list of
>>> hardware devices in your system.  That's hardly anything sensitive....
>> We actually had a very vocal minority about all of that which ended up 
>> putting us in the unfortunate position of generating a random UUID instead 
>> of using a hardware UUID from hal :-/
> 
> Tinfoil hat responses indeed!  Ok, if those folks are really that
> crazy, my suggestion then would be to do a "ifconfig -a > /dev/random"

heh, along those lines you could also do

	dmesg > /dev/random

<grin>

dmesg often has machine-unique identifiers of all sorts (including the 
MAC address, if you have an ethernet driver loaded)

	Jeff