[Freedombox-discuss] Entropy from the soundcard

Frank frank at debian-nas.org
Mon Sep 19 14:55:28 UTC 2011

On Mon, Sep 19, 2011 at 1:06 AM, Sandy Harris
<sandyinchina at gmail.com> wrote:

>On Fri, Sep 16, 2011 at 9:25 PM, Daniel Kahn Gillmor
><dkg at fifthhorseman.net> wrote:
>> Frank from debian-nas.org wrote me off-list about entropy daemons,
>> and agreed i could share his notes publicly.
>> He wrote:
>>> haveged runs just fine on both my QNAP TS-109 (Marvell Kirkwood) and
>>> Linksys NSLU2 (ixp4xx) ARM computers running Debian Squeeze.
>I'm confused. You are saying Haveged runs fine on ARM, but it is
>inherently hardware-dependent and the authors do not seem to
>know of an ARM port.
>The Havege web site says on the overview page:
>" low-power superscalar processors (e.g. StrongARM, Intel Xscale) ...
>" HAVEGE can also be implemented on these platforms. A demo ...
>" for ... a Xscale processor is available.
>Not that this has been implemented, just that it could be, and
>there's a demo for one CPU.
>Looking at their downloads page:
>I find prebuilt binaries for a few architectures, but nothing at
>all for ARM, and for Debian, only x86 and Power PC.

Hi Sandy,

if you do a search on the Debian repositories (i.e. package.debian.org ),
you'll notice that haveged (
http://packages.debian.org/squeeze-backports/haveged ) is in the
squeeze-backports repository. I installed the armel build from there onto
my Squeeze installation on my Linksys NSLU2 and QNAP TS-109 machines.

As I reported, haveged produces plenty of entropy on these machines, which
when tested with ENT ( http://packages.debian.org/squeeze/ent ), the
entropy appears to be of sufficient quality. In fact, the amount of entropy
generated is so much that I don't think timer entropy daemon or random
sound are interesting projects to go after. 

I haven't tested turbid, but it needs to generate an order of magnitude of
entropy more than randomsound before it'll be a contender for entropy
generation in my opinion. And I'm personally not very fond of having an
active microphone hooked up in the room where my server is.


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