To: linux-kernel@vger.kernel.org
From: Gunter Ohrner <G.Ohrner@post.rwth-aachen.de>
Subject: Re: Entropy Pool Contents
Date: Thu, 23 Nov 2006 22:40:36 +0100
Message-ID: <ek54hf$icj$2@sea.gmane.org>
References: <ek2nva$vgk$1@sea.gmane.org> <Pine.LNX.4.61.0611230107240.26845@yvahk01.tjqt.qr>
Reply-To: G.Ohrner@post.rwth-aachen.de
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Jan Engelhardt wrote:
>>Hornburg:~# cat /proc/sys/kernel/random/entropy_avail
>>0
> You really must have bad luck with your entropy...

IMHO something really fishy's going on there. If I explicitely write data
into the pool, it shouldd not stay at "zero", from wwhat I understood about
how /dev/*random work.

> Disk activities are "somewhat predictable", like network traffic, and
> hence are not (or should not - have not checked it) contribute to the
> pool.

Well, they do, block device operations do, using the function
add_blkdev_randomness, as far as I know.

> Note that urandom is the device which _always_ gives you data, and 
> when the pool is exhausted, returns pseudorandom data.

I know, and running on deterministically computed random values only for
days in a row is no situation I'm paticularily happy about...

I'm mainly wondering why writing stuff to /dev/*random does not change the
entropy from zero to at least any low non-zero value...

Greetings,

  Gunter

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