Date: Fri, 12 Jan 2001 01:05:12 -0600 (CST) From: Nate Dannenberg <natedac@kscable.com> To: <current@freebsd.org> Subject: Re: entropy bikesheds Message-ID: <Pine.BSF.4.31.0101120042000.56776-100000@flute.daconcepts.dyndns.org> In-Reply-To: <200101120619.f0C6JQI12558@gratis.grondar.za>
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Mark Murray <mark@grondar.za> wrote: > Can we decide this, please - do we want secure startup (which will > take some effort to achieve), or can we say "screw it" and start > insecure like the old system? > > I'm happy to accomodate folks, but the constant lack of concensus > combined with extreme positions is wearing a bit thin. Although I'm not a coder on this platform, I do have an idea that we sometimes use on my hobby platform, maybe this might help... Start some kind of hardware-managed timer at the earliest possible opportunity (perhaps start it in the boot loader!), then when you need to pick up your first seed, read the timer's value and seed your random generator from that. The idea is to catch that timer at an unknown condition, and certainly the computer is not going to boot in the exact same amount of time, every time it's restarted. This would be especially true if the boot sequence gets interrupted (to load another kernel perhaps) or the user forces the machine into single-user mode while it's booting. In my hobby platform, it's common to start the timer, then grab a value from it after the user hits a key after viewing some introduction screen. The value grabbed is often used as the actual random number, but it could be just as useful if used to seed a random generator. If you're particularly paranoid, you set both timers for 32-bit mode, start one first thing at startup, and the other when the user hits the key, then read both of them the first time a random number is needed. Seed your random generator from that, along with any other sources you can (such as the video raster counter and the sound device's readable oscillator, set to generate a noise waveform). Just my two cents. -- ___________________________________ _____ _____ | _///@@@| | | natedac@kscable.com /'//ZZ@@|____ | | |'''/ |'/@7 | | http://home.kscable.com/natedac |`'| `~~' | | | `| .--. | | C64/C128 - What's *YOUR* hobby? | `\____|___\ | | \_ | | |___________________________________ \_____| _____| To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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