On Tue, Jul 23, 2013 at 10:04 AM, KPJ <kpj@sics.se> wrote:
A sound card in your box then can deliver random numbers.

You may wish to look into this:

http://www.guyrutenberg.com/2010/05/14/audio-based-true-random-number-generator-poc/

This may also interest you;

http://www.volkerschatz.com/science/audiorng.html

For Debian-based Linux distros, e.g. Ubuntu, this is automated by the "randomsound" package:

  http://packages.debian.org/wheezy/randomsound

  sudo apt-get install  randomsound

There's also audio-entropyd, but I haven't used that:

  http://www.vanheusden.com/aed/

He has links to other entropy generators.