Date: Mon, 19 Aug 2013 08:40:06 +0100 From: Mark R V Murray <mark@grondar.org> To: Warner Losh <imp@bsdimp.com> Cc: Tim Kientzle <tim@kientzle.com>, FreeBSD-arch Arch <freebsd-arch@freebsd.org>, secteam@freebsd.org, =?iso-8859-1?Q?Dag-Erling_Sm=F8rgrav?= <des@des.no> Subject: Re: random(4) plugin infrastructure for mulitple RNG in a modular fashion Message-ID: <F8CEB750-7C07-42A5-97B0-40D742AD1C90@grondar.org> In-Reply-To: <EE0B6A6A-38CD-4DB9-A811-F4C0BF83109E@bsdimp.com> 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> <3513A465-AD8D-4DDC-9408-2F89F9B86404@grondar.org> <EE0B6A6A-38CD-4DB9-A811-F4C0BF83109E@bsdimp.com>
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--Apple-Mail=_303BAD32-22C2-4AAD-80BF-6DA5FB281728 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=windows-1252 On 19 Aug 2013, at 08:24, Warner Losh <imp@bsdimp.com> wrote: >> How would they get a score, and how would it be decided which is = better? How is the score "calibrated"? >=20 > For timecounters, we make judgements based on how good or bad we think = the timekeeping ability of the underlying device. I'd imagine that we'd = rate the hardware RNGs high, and the fallback means of harvesting = entropy from interrupts medium, and anything that's really really bad as = low. This would allow for the hardware RNGs to override the other = sources of entropy, while still allowing fallback to reasonable entropy = on devices that are known suspect (While still allowing the pig-headed = and/or externally constrained folks to use the bad sources). Aaah - so its a coarse good/average/bad thing, rather than a = fine-grained number giving precise/critical ordering? > For the mixers, the scoring mechanism makes less sense. You'd want = more of an ordered list specified by the user to dictate policy to = choose between nothing, fortuna and yarrow. The mixers won't care, correct. As for the rest, its a bit of a tree of = choices: HW branch - choice of "good" sources only (?). SW branch - = choice of Yarrow/Fortuna and which sources (currently four, but will be = increased) to harvest from. > You'd also want a parameter to deal with failure here: panic or block. Right, and a default for GENERIC. M --=20 Mark R V Murray --Apple-Mail=_303BAD32-22C2-4AAD-80BF-6DA5FB281728 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 iQCVAwUBUhHL1t58vKOKE6LNAQrfxAP/c1hmEoOkG5Ty8aFjBUVm4vmx1nSFvHj1 LTVyMGNsCc6IkunN56msq2ACGmXxVd8is3EK0hIldlrwnL+couWwzNpHikqdbzDu pTSfPUCtMHYAW8Hx+R6T+aFaGjsXMeor94eT+OBMg97+T0eSgt17OB8Kxvq1kW+e iPkAy7TnK1o= =6a86 -----END PGP SIGNATURE----- --Apple-Mail=_303BAD32-22C2-4AAD-80BF-6DA5FB281728--
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