Date: Mon, 07 Mar 2005 20:00:25 +0000 From: Mark Murray <markm@FreeBSD.ORG> To: Garrett Wollman <wollman@khavrinen.lcs.mit.edu> Cc: Mark Murray <markm@FreeBSD.ORG> Subject: Re: New entropy source proposal. Message-ID: <200503072000.j27K0Phv035052@grovel.grondar.org> In-Reply-To: Your message of "Mon, 07 Mar 2005 14:44:49 EST." <200503071944.j27JiniV006061@khavrinen.lcs.mit.edu>
next in thread | previous in thread | raw e-mail | index | archive | help
Garrett Wollman writes: > The usual noise source is thermal noise in the machine itself. The > process that I've heard described involves: > > 0) Disconnecting any input sources. > 1) Turning the input gain all the way up. > 2) Taking only the least-significant bit of each sample. The random_harvest(9) call would do this by reading (say) 16 bits out of the DSP, and handing it over as harvested entropy while claiming it had 1 bit of useful randomness. Any other gratuitous randomness in the sample would provide "free" perturbation of the entropy pool. > In order to use this in FreeBSD, we would probably want a compile > option in the sound drivers to disable their use for other purposes > (e.g., generating sound). I can think of a way to do this with sysctls. M -- Mark Murray iumop ap!sdn w,I idlaH
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200503072000.j27K0Phv035052>