Date: Wed, 19 Jul 2000 20:09:48 +0200 From: Poul-Henning Kamp <phk@critter.freebsd.dk> To: Warner Losh <imp@village.org> Cc: Mark Murray <mark@grondar.za>, current@FreeBSD.ORG Subject: Re: randomdev entropy gathering is really weak Message-ID: <946.964030188@critter.freebsd.dk> In-Reply-To: Your message of "Wed, 19 Jul 2000 11:33:55 MDT." <200007191733.LAA82735@harmony.village.org>
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In message <200007191733.LAA82735@harmony.village.org>, Warner Losh writes: >Another good source would be if you had a Cesium clock and a GPS >receiver. The delay due to atmospherics is another good source of >random data. This varies +- 25ns and is highly locale dependent. One >can measure this variance down to the nanosecond easily (giving about >5 bits of randomness) and with a lot of effort down to the pico second >level, which would give you about 15 bits of randomness. A geiger counter and a smoke-detector would be *so much* cheaper and give more bits per second :-) >It certainly would be better than nothing and would be a decent source >of randomness. It would be my expectation that if tests were run to >measure this randomness and the crypto random tests were applied, >we'd find a fairly good source. The trick here is to actually measure the quality of our entropy. I have asked Markm to provide us with some kernel option which can be used to get a copy of the entropy so we can study the quality off it. BTW: You have *no* idea how much I envy your access to high quality timing hardware :-) -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD coreteam member | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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