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

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Message-ID: <20071205144934.GL7259@thunk.org>
Date:	Wed, 5 Dec 2007 09:49:34 -0500
From:	Theodore Tso <tytso@....edu>
To:	Mike McGrath <mmcgrath@...hat.com>
Cc:	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?

On Wed, Dec 05, 2007 at 08:26:19AM -0600, Mike McGrath wrote:
>
> Ok, whats going on here is an issue with how the smolt RPM installs the 
> UUID and how Fedora's Live CD does an install.  It's a complete false alarm 
> on the kernel side, sorry for the confusion.

BTW, You may be better off using "uuidgen -t" to generate the UUID in
the smolt RPM, since that will use 12 bits of randomness from
/dev/random, plus the MAC, address and timestamp.  So even if there is
zero randomness in /dev/random, and the time is January 1, 1970, at
least the MAC will contribute some uniqueness to the UUID.

      	      	   	      	   	      	 - Ted
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