Date: Thu, 13 Sep 2007 22:57:57 +0200 From: Per olof Ljungmark <peo@intersonic.se> To: freebsd-questions@freebsd.org Subject: Re: /dev/random question Message-ID: <46E9A455.4090703@intersonic.se> In-Reply-To: <20070913174537.GA11683@slackbox.xs4all.nl> References: <46E94F9A.6050707@intersonic.se> <20070913153630.GA9448@slackbox.xs4all.nl> <20070913173155.0bad12b2@gumby.homeunix.com.> <20070913174537.GA11683@slackbox.xs4all.nl>
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Roland Smith wrote: > On Thu, Sep 13, 2007 at 05:31:55PM +0100, RW wrote: >> On Thu, 13 Sep 2007 17:36:30 +0200 >> Roland Smith <rsmith@xs4all.nl> wrote: >> >>> On Thu, Sep 13, 2007 at 04:56:26PM +0200, Per olof Ljungmark wrote: >>>> Hi, >>>> >>>> Could someone on the list point me to a document that explains the >>>> functionality of /dev/random in FreeBSD in a little more depth than >>>> the man page? In other OS's I've looked at random and urandom are >>>> different, here it's a symlink (talking about RELENG-6 onwards). >>> >>> FreeBSD uses the yarrow algorithm, as mentioned in random(4). See >>> http://en.wikipedia.org/wiki/Yarrow_algorithm >>> http://www.schneier.com/yarrow.html >> Yarrow is reseeded with interrupt entropy, and is supposedly good >> enough not to require the amount of entropy to be tracked. >> So /dev/random need not block, and there's no need for a separate >> non-blocking device. > > On the website it says that the original yarrow algorithm is no longer > supported. It seems to have been replaced by the fortuna algorithm. > > I can't see from the source if /usr/src/sys/dev/random/yarrow.* use the > original yarrow algorithm, or the improved yarrow-160 aka fortuna. The use of > crypto/rijndael/rijndael-api-fst.h and crypto/sha2/sha2.h seem to > indicate the latter though. Should I conclude then that randomness is sufficient and performance is a non-issue?
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