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

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Date:	Sat, 08 Dec 2007 13:31:09 -0500
From:	Jeff Garzik <jeff@...zik.org>
To:	Theodore Tso <tytso@....edu>, Mike McGrath <mmcgrath@...hat.com>,
	Jon Masters <jonathan@...masters.org>,
	Matt Mackall <mpm@...enic.com>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Ray Lee <ray@...rabbit.org>, Adrian Bunk <bunk@...nel.org>,
	Marc Haber <mh+linux-kernel@...schlus.de>,
	linux-kernel@...r.kernel.org
Subject: Re: Why does reading from /dev/urandom deplete entropy so much?

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



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