From owner-freebsd-security Mon Sep 4 14:36:38 2000 Delivered-To: freebsd-security@freebsd.org Received: from freefall.freebsd.org (freefall.FreeBSD.org [216.136.204.21]) by hub.freebsd.org (Postfix) with ESMTP id DB34737B42C; Mon, 4 Sep 2000 14:36:30 -0700 (PDT) Received: from localhost (kris@localhost) by freefall.freebsd.org (8.9.3/8.9.2) with ESMTP id OAA66872; Mon, 4 Sep 2000 14:36:30 -0700 (PDT) (envelope-from kris@FreeBSD.org) X-Authentication-Warning: freefall.freebsd.org: kris owned process doing -bs Date: Mon, 4 Sep 2000 14:36:30 -0700 (PDT) From: Kris Kennaway To: Adam Laurie Cc: James Wyatt , Garrett Wollman , Adam Back , security@FreeBSD.org Subject: Re: yarrow & /dev/random In-Reply-To: <39B3992B.7B823DEE@algroup.co.uk> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-security@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org On Mon, 4 Sep 2000, Adam Laurie wrote: > Kris Kennaway wrote: > > > > On Sun, 27 Aug 2000, James Wyatt wrote: > > > > > On servers with no regular keyboard or mouse use, there is usually enough > > > entropy in the disk and network IO to serve the purpose. Small servers > > > with low net and disk entropy often get used as consoles for busier > > > servers. Your mileage may vary, of course. What other sources of entropy > > > might one consider? Maybe an AM radio tuned to static hooked into > > > /dev/audio to get random samples? - Jy@ > > > > My observations suggest that a sound card tuned to maximum input gain with > > no microphone input (i.e. sampling noise in the card) is a very good > > source of randomness, with at least 6 bits of entropy per 16 bit sample > > for most cards, which can be sampled at 44Khz (i.e. about 32 kilobytes of > > randomness per second, far in excess of what Yarrow needs). > > > > More than enough for even heavy server needs. > > This is only safe to do if you can guarantee that your sound card is > protected from outside influence - e.g. radio transmissions putting > known noise into your data. TEMPEST shielding would be a good start. If interference from men in black is part of your threat model ;-) Kris -- In God we Trust -- all others must submit an X.509 certificate. -- Charles Forsythe To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-security" in the body of the message