Date: Fri, 16 Apr 2004 19:30:39 +1000 From: Peter Jeremy <PeterJeremy@optushome.com.au> To: Mark Murray <mark@grondar.org> Cc: freebsd-current@freebsd.org Subject: Re: dev/random Message-ID: <20040416093039.GE53327@cirb503493.alcatel.com.au> In-Reply-To: <200404151448.i3FEm9In021190@grimreaper.grondar.org> References: <20040414090506.GA25565@server.vk2pj.dyndns.org> <200404151448.i3FEm9In021190@grimreaper.grondar.org>
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On Thu, Apr 15, 2004 at 03:48:09PM +0100, Mark Murray wrote: >Peter Jeremy writes: >> If you don't need a great deal of entropy, you might be able to get >> away with stirring in the time of day, CPU cycle counter[1], and maybe >> time a couple of arbitrary disk seeks. If you had a _really_ cheap >> stirring function, maybe stir in all of KVM (this should vary slightly >> from boot to boot). This should be enough entropy to get to the >> point where you can start loading or acquiring reasonable entropy. > >Check /etc/rc.d/*random* - we've been doing this for years. :-) I meant that the kernel should seed /dev/random before it even starts init(8). I understood that one of the problems with /etc/rc.d/random was that you may need to have some entropy available to mount root so you can get to /etc/rc.d/random. (And /etc/rc.d/random doesn't help when you boot into single user mode and can't run ed or vi because there's no entropy). >> Of course, the default behaviour of automatically building ssh host >> keys as part of the boot sequence (when there's virtually no entropy >> available) is probably undesirable. > >We understand the problem all too well. > >There are two conflicting parts; 1) Starting the device early enough >and 2) making it secure (enough). One option (which may have already been implemented, I haven't done a 5-CURRENT install for a long time) would be to generate the host keys as part of sysinstall before rebooting. There's potentially a fair amount of entropy available by the end of the system installation. (In any case, it's unlikely to be less than what is available early during the boot process). -- Peter Jeremy
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