From owner-freebsd-arch@FreeBSD.ORG Mon Aug 19 07:14:09 2013 Return-Path: Delivered-To: freebsd-arch@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTP id 3650DCE5; Mon, 19 Aug 2013 07:14:09 +0000 (UTC) (envelope-from mark@grondar.org) Received: from gromit.grondar.org (grandfather.grondar.org [IPv6:2a01:348:0:15:5d59:5c20:0:2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id EB82A276C; Mon, 19 Aug 2013 07:14:08 +0000 (UTC) Received: from graveyard.grondar.org ([88.96.155.33] helo=gronkulator.grondar.org) by gromit.grondar.org with esmtpsa (TLSv1:AES128-SHA:128) (Exim 4.80.1 (FreeBSD)) (envelope-from ) id 1VBJf7-000LfL-RN; Mon, 19 Aug 2013 08:14:04 +0100 Subject: Re: random(4) plugin infrastructure for mulitple RNG in a modular fashion Mime-Version: 1.0 (Mac OS X Mail 6.5 \(1508\)) Content-Type: multipart/signed; boundary="Apple-Mail=_FB4B5D4A-A92B-46C9-B973-2C04BF738D45"; protocol="application/pgp-signature"; micalg=pgp-sha512 From: Mark R V Murray In-Reply-To: <12B58C72-CFE3-4AD4-AD03-462A10E431D9@bsdimp.com> Date: Mon, 19 Aug 2013 08:13:53 +0100 Message-Id: <3513A465-AD8D-4DDC-9408-2F89F9B86404@grondar.org> References: <20130807183112.GA79319@dragon.NUXI.org> <86pptfnu33.fsf@nine.des.no> <20130815231713.GD76666@x96.org> <20130816002625.GE76666@x96.org> <9B274F48-0C88-4117-BEAC-1A555772A3C5@grondar.org> <86a9kf733d.fsf@nine.des.no> <0C97B866-A169-4141-8368-AA7F5B5382F4@grondar.org> <861u5r71zi.fsf@nine.des.no> <892B11BD-396D-4F82-B97C-753F72CA494D@grondar.org> <86r4dr5j3p.fsf@nine.des.no> <4C1BD77C-8C6B-4044-9285-5978A3BC4B70@kientzle.com> <12B58C72-CFE3-4AD4-AD03-462A10E431D9@bsdimp.com> To: Warner Losh X-Mailer: Apple Mail (2.1508) X-SA-Score: -2.2 Cc: Tim Kientzle , FreeBSD-arch Arch , secteam@freebsd.org, =?iso-8859-1?Q?Dag-Erling_Sm=F8rgrav?= X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 19 Aug 2013 07:14:09 -0000 --Apple-Mail=_FB4B5D4A-A92B-46C9-B973-2C04BF738D45 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=windows-1252 On 19 Aug 2013, at 08:09, Warner Losh wrote: >> Besides Yarrow and Fortuna mixers, we could then >> offer a "null mixer" option that selected the single >> "best" entropy source and passed it directly through. >=20 > I'm still wondering why timecounters aren't the right model to follow = here, where you can have several compiled into the kernel and the one = with the best score wins. How would they get a score, and how would it be decided which is better? = How is the score "calibrated"? >> Users could compile the null mixer into the kernel >> and load a single HW RNG driver to have precise >> control over /dev/random. Interrupt harvesting would >> be the lowest-quality source as a fall back. >>=20 >> In particular, this has a reasonable failure mode if >> someone built a kernel with only a single HW entropy >> source and the null mixer: >> * On hardware with that source, they would get >> full-speed HW entropy. >> * On hardware without that source, they would get >> the old blocking /dev/random that we had before >> Yarrow, the one that used only interrupt harvesting. >=20 > Assuming there was enough interrupt entropy to generate bits=85 See Ferguson & Schneier on this (qv my follow-up). M --=20 Mark R V Murray --Apple-Mail=_FB4B5D4A-A92B-46C9-B973-2C04BF738D45 Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=signature.asc Content-Type: application/pgp-signature; name=signature.asc Content-Description: Message signed with OpenPGP using GPGMail -----BEGIN PGP SIGNATURE----- Version: GnuPG/MacGPG2 v2.0.20 (Darwin) Comment: GPGTools - http://gpgtools.org iQCVAwUBUhHFt958vKOKE6LNAQpttwP8DqaLAcLTQEWdfQCdrZkv+hdk/Rt5dPXT FIYqkknkPoLX6Ly6dyUmlOLtFAsyAkG428Y8gpN28pi/WkTIc5WHq/B2XMJsmDWN Zl2P0HeGH1IqrmwioKGBE92hASJ6x8hosmICFN7mkf5DVTUDs7NVkChHPPl31DG7 J9+w81Re2Xo= =zMFZ -----END PGP SIGNATURE----- --Apple-Mail=_FB4B5D4A-A92B-46C9-B973-2C04BF738D45--