Subject: Re: insufficient entropy for rnd
To: Peter Hendrickson <>
From: Daniel Carosone <>
List: tech-crypto
Date: 08/21/2003 10:22:47
On Wed, Aug 20, 2003 at 09:23:43PM -0000, Peter Hendrickson wrote:
> I have some code which implements an entropy monitoring daemon.  When
> your entropy pool runs low, it frobs the disk until the level is
> restored:

Without actually having looked at it yet, this is useful. There
are a whole class of things that can be done to improve "entropy"
gathering from userspace, this is one useful idea.

Many other things can help, especially as you (root) can write to
/dev/random to stir more data into the pool from userspace sources.

Other ideas, for anyone interested in taking this further:
 - optical mice and some sort of moving or scattering surface.
 - audio devices (take diff between left & right channels)
 - radio/tv tuner devices, re-tuned with random data
 - webcams pointed at lava lamps, fish tanks, busy streets, etc.
 - various hobby or commercial rng devices (diode noise, etc)

Most of these measures are basically unnecessary if you have one
of the newer i386 motherboards with hardware RNG, and for most
other general-purpose systems after they've been running a while
even without.

The biggest challenge is to find good sources early in the boot