Date: Wed, 19 Jul 2000 15:30:37 -0400 (EDT) From: Peter Dufault <dufault@hda.com> To: Warner Losh <imp@village.org> Cc: Peter Dufault <dufault@hda.com>, current@FreeBSD.ORG Subject: Re: randomdev entropy gathering is really weak Message-ID: <200007191930.PAA99620@hda.hda.com> In-Reply-To: <200007191746.LAA82887@harmony.village.org> from Warner Losh at "Jul 19, 2000 11:46:01 am"
next in thread | previous in thread | raw e-mail | index | archive | help
> In message <200007191308.JAA98111@hda.hda.com> Peter Dufault writes: > : > The reason why ntp is interesting is that we compare the received data > : > with our unpredictable local clock. It is the result of this comparison > : > which is good entropy bits. > : > : Is the resolution of thermal sensors on many new motherboards and > : CPU high enough to get thermal randomness? > > Yes. You'll also find that the voltage drifts as well. However, I > doubt you'd be able to get more than 1 bit out of the voltage > readings. The thermal readings, depending on their precision, would > also yield several random bits. But this several may be only 3 or 4. > The temperature varies based on work load and on the climate controls > in place at the site. I actually meant can you get real randomness, measuring the thermal noise in the on-chip temperature diode should be a good source of randomness. Except they are probably "kind" enough to fully filter it out. Peter -- Peter Dufault (dufault@hda.com) Realtime development, Machine control, HD Associates, Inc. Fail-Safe systems, Agency approval To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200007191930.PAA99620>