From owner-freebsd-stable@FreeBSD.ORG Mon Oct 23 17:37:31 2006 Return-Path: X-Original-To: freebsd-stable@freebsd.org Delivered-To: freebsd-stable@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 4CF2A16A407 for ; Mon, 23 Oct 2006 17:37:31 +0000 (UTC) (envelope-from rsmith@xs4all.nl) Received: from smtp-vbr8.xs4all.nl (smtp-vbr8.xs4all.nl [194.109.24.28]) by mx1.FreeBSD.org (Postfix) with ESMTP id 651C443D76 for ; Mon, 23 Oct 2006 17:37:14 +0000 (GMT) (envelope-from rsmith@xs4all.nl) Received: from slackbox.xs4all.nl (slackbox.xs4all.nl [213.84.242.160]) by smtp-vbr8.xs4all.nl (8.13.8/8.13.8) with ESMTP id k9NHbDhu026467; Mon, 23 Oct 2006 19:37:13 +0200 (CEST) (envelope-from rsmith@xs4all.nl) Received: by slackbox.xs4all.nl (Postfix, from userid 1001) id EADD0B840; Mon, 23 Oct 2006 19:37:12 +0200 (CEST) Date: Mon, 23 Oct 2006 19:37:12 +0200 From: Roland Smith To: freebsd-stable@freebsd.org, matthieu.michaud@epita.info Message-ID: <20061023173712.GA17079@slackbox.xs4all.nl> Mail-Followup-To: freebsd-stable@freebsd.org, matthieu.michaud@epita.info References: <45393A29.3080100@epita.info> <200610231649.k9NGnLgQ065468@lurza.secnetix.de> <20061023172712.GA16379@slackbox.xs4all.nl> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="k+w/mQv8wyuph6w0" Content-Disposition: inline In-Reply-To: <20061023172712.GA16379@slackbox.xs4all.nl> X-GPG-Fingerprint: 1A2B 477F 9970 BA3C 2914 B7CE 1277 EFB0 C321 A725 X-GPG-Key: http://www.xs4all.nl/~rsmith/pubkey.txt X-GPG-Notice: If this message is not signed, don't assume I sent it! User-Agent: Mutt/1.5.11 X-Virus-Scanned: by XS4ALL Virus Scanner Cc: Subject: Re: VIA C7 support X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 23 Oct 2006 17:37:31 -0000 --k+w/mQv8wyuph6w0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Oct 23, 2006 at 07:27:12PM +0200, Roland Smith wrote: > 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. > > >=20 > > > you are right. do you know an easy way to evaluate this quality ? > >=20 > > There is no easy way, I'm afraid. >=20 > Start reading here: http://www.random.org/essay.html > And follow the links. >=20 > A test of 1 MB random data with "ent" [http://www.fourmilab.ch/random/]: >=20 > dd if=3D/dev/random of=3Drand.dat bs=3D1k count=3D1k > ./ent rand.dat=20 > Entropy =3D 7.999843 bits per byte. >=20 > Optimum compression would reduce the size > of this 1048576 byte file by 0 percent. >=20 > Chi square distribution for 1048576 samples is 227.43, and randomly > would exceed this value 75.00 percent of the times. >=20 > Arithmetic mean value of data bytes is 127.6223 (127.5 =3D random). > Monte Carlo value for Pi is 3.133839164 (error 0.25 percent). > Serial correlation coefficient is -0.000504 (totally uncorrelated =3D 0.0= ). >=20 >=20 > According to the same fourmilab page this is quite decent. There is > about 1 bit of entropy in approx. ~6000 bytes!=20 That should be 1 bit of _non_ entropy. Oops. > The chi square value is > of the same order as one generated by timing radioactive decay events. Repeating the cycle of dd/ent commands gives varying values for the chi square test. It probably depends on the ratio of random bytes that you need versus the number of really random bytes harvested by the system. =20 Roland --=20 R.F.Smith http://www.xs4all.nl/~rsmith/ [plain text _non-HTML_ PGP/GnuPG encrypted/signed email much appreciated] pgp: 1A2B 477F 9970 BA3C 2914 B7CE 1277 EFB0 C321 A725 (KeyID: C321A725) --k+w/mQv8wyuph6w0 Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.5 (FreeBSD) iD8DBQFFPP3IEnfvsMMhpyURAozvAJ41esEmw6HNtj5NgfI6S9b2tp4X7wCcDSgF YtYknOJF28fpE6NLBqeSEoY= =PNwy -----END PGP SIGNATURE----- --k+w/mQv8wyuph6w0--