VIA C7 support
rsmith at xs4all.nl
Mon Oct 23 17:27:22 UTC 2006
On Mon, Oct 23, 2006 at 06:49:21PM +0200, Oliver Fromme wrote:
> Matthieu Michaud wrote:
> > Oliver Fromme wrote:
> > > Also take into account that you usually don't read that
> > > much data from /dev/random. Quality is much more important
> > > than speed.
> > you are right. do you know an easy way to evaluate this quality ?
> There is no easy way, I'm afraid.
Start reading here: http://www.random.org/essay.html
And follow the links.
A test of 1 MB random data with "ent" [http://www.fourmilab.ch/random/]:
dd if=/dev/random of=rand.dat bs=1k count=1k
Entropy = 7.999843 bits per byte.
Optimum compression would reduce the size
of this 1048576 byte file by 0 percent.
Chi square distribution for 1048576 samples is 227.43, and randomly
would exceed this value 75.00 percent of the times.
Arithmetic mean value of data bytes is 127.6223 (127.5 = random).
Monte Carlo value for Pi is 3.133839164 (error 0.25 percent).
Serial correlation coefficient is -0.000504 (totally uncorrelated = 0.0).
According to the same fourmilab page this is quite decent. There is
about 1 bit of entropy in approx. ~6000 bytes! The chi square value is
of the same order as one generated by timing radioactive decay events.
[plain text _non-HTML_ PGP/GnuPG encrypted/signed email much appreciated]
pgp: 1A2B 477F 9970 BA3C 2914 B7CE 1277 EFB0 C321 A725 (KeyID: C321A725)
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