Date: Mon, 19 Aug 2013 16:01:52 -0600 From: Warner Losh <imp@bsdimp.com> To: Mark R V Murray <mark@grondar.org> 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: <629B621F-B166-4D66-A4E6-ED9B966E7A21@bsdimp.com> In-Reply-To: <F8CEB750-7C07-42A5-97B0-40D742AD1C90@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> <3513A465-AD8D-4DDC-9408-2F89F9B86404@grondar.org> <EE0B6A6A-38CD-4DB9-A811-F4C0BF83109E@bsdimp.com> <F8CEB750-7C07-42A5-97B0-40D742AD1C90@grondar.org>
next in thread | previous in thread | raw e-mail | index | archive | help
On Aug 19, 2013, at 1:40 AM, Mark R V Murray wrote: > 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). >=20 > Aaah - so its a coarse good/average/bad thing, rather than a = fine-grained number giving precise/critical ordering? >=20 >> 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. >=20 > 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. >=20 >> You'd also want a parameter to deal with failure here: panic or = block. >=20 > Right, and a default for GENERIC. Exactly... Warner
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?629B621F-B166-4D66-A4E6-ED9B966E7A21>