[13692] in bugtraq
Re: Tempfile vulnerabilities
daemon@ATHENA.MIT.EDU (Werner Koch)
Thu Feb 3 15:49:36 2000
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Date: Wed, 2 Feb 2000 23:01:10 +0100
Reply-To: Werner Koch <wk@GNUPG.ORG>
From: Werner Koch <wk@GNUPG.ORG>
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In-Reply-To: <200002022136.OAA09251@cvs.openbsd.org>; from
deraadt@cvs.openbsd.org on Wed, Feb 02, 2000 at 02:36:20PM -0700
On Wed, 2 Feb 2000, Theo de Raadt wrote:
> I suppose then that anyone who attacks a machine which relies on
> /dev/random -- a world readable device -- should do the following:
>
> cat /dev/random > /dev/null &
Yep.
> Crypto software which uses those devices should be doing some kind of
> checking to make sure that they are getting at least good entropy. I
The good thing is that /dev/random blocks until there is enough entropy
available. /dev/urandom does not block but continues to return random
bytes by using a PRNG.
> suppose I could even argue that the random devices should make it easy
> for customer software to determine that entropy is low.
There is also an ioctl() to query some statistics. OpenBSD has some
more kinds of random devices but I don't know much about them.
I have not checked the latest Linux kernels but rumors are that this
device has been enhanced.
--
Werner Koch at guug.de www.gnupg.org keyid 621CC013
