Date: Sat, 10 Nov 2001 21:34:52 -0800 (PST) From: John Kozubik <john@kozubik.com> To: Mike Silbersack <silby@silby.com> Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: CPU Temp and Fan speed as entropy? Message-ID: <Pine.BSF.4.21.0111102126430.68269-100000@www.kozubik.com> In-Reply-To: <20011109095347.R46119-100000@achilles.silby.com>
next in thread | previous in thread | raw e-mail | index | archive | help
CPU temp and fan speed may or may not be truly random - regardless, I would be wary of using them as random seeds. First, I suspect that the range of values is quite small - how much does your temp and fan speed actually fluctuate over time ? Second, I don't have a bios like this in front of me to examine, but I doubt the granularity is greater than one decimal place. Comments ? Due to the small range that these numbers will fall in, I would think the effectiveness of these values as a random seed are directly related to the number of places to the right of the decimal these values are measured in. ----- John Kozubik - john@kozubik.com - http://www.kozubik.com On Fri, 9 Nov 2001, Mike Silbersack wrote: > > Out of curiousity, has anyone looked into using cpu temperature and fan > speed as an entropy source? The thought came to last time I was in bios, > looking at the temperature stats; to my untrained eye, it sure looks like > those numbers bounce around a lot. I think most motherboards are coming > with such sensors onboard these days, and I also believe that we have > userland support for reading the values. > > I think we're doing just fine wrt entropy in -current, but it would still > be rather neat to harvest hardware-derived entropy on a wide variety of > machines. > > Just curious, > > Mike "Silby" Silbersack > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-hackers" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?Pine.BSF.4.21.0111102126430.68269-100000>