From owner-freebsd-stable@FreeBSD.ORG Mon Oct 23 17:27:21 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 DD3FB16A415 for ; Mon, 23 Oct 2006 17:27:21 +0000 (UTC) (envelope-from rsmith@xs4all.nl) Received: from smtp-vbr5.xs4all.nl (smtp-vbr5.xs4all.nl [194.109.24.25]) by mx1.FreeBSD.org (Postfix) with ESMTP id EC31743D62 for ; Mon, 23 Oct 2006 17:27:14 +0000 (GMT) (envelope-from rsmith@xs4all.nl) Received: from slackbox.xs4all.nl (slackbox.xs4all.nl [213.84.242.160]) by smtp-vbr5.xs4all.nl (8.13.8/8.13.8) with ESMTP id k9NHRCLb088861; Mon, 23 Oct 2006 19:27:13 +0200 (CEST) (envelope-from rsmith@xs4all.nl) Received: by slackbox.xs4all.nl (Postfix, from userid 1001) id ACFBAB840; Mon, 23 Oct 2006 19:27:12 +0200 (CEST) Date: Mon, 23 Oct 2006 19:27:12 +0200 From: Roland Smith To: freebsd-stable@freebsd.org, matthieu.michaud@epita.info Message-ID: <20061023172712.GA16379@slackbox.xs4all.nl> Mail-Followup-To: freebsd-stable@freebsd.org, matthieu.michaud@epita.info References: <45393A29.3080100@epita.info> <200610231649.k9NGnLgQ065468@lurza.secnetix.de> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="gBBFr7Ir9EOA20Yy" Content-Disposition: inline In-Reply-To: <200610231649.k9NGnLgQ065468@lurza.secnetix.de> 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 17:27:22 -0000 --gBBFr7Ir9EOA20Yy Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable 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. 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=3D/dev/random of=3Drand.dat bs=3D1k count=3D1k =2E/ent rand.dat=20 Entropy =3D 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 =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). 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. 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) --gBBFr7Ir9EOA20Yy Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.5 (FreeBSD) iD8DBQFFPPtwEnfvsMMhpyURAvgXAJ0X/GasX9YloXL5MZ0jZORrt3hVKgCfdHV2 EW2grILeodlMeLTmDdyQMxs= =yhKw -----END PGP SIGNATURE----- --gBBFr7Ir9EOA20Yy--