Date: Mon, 17 Jul 2000 19:43:06 +0200 From: Mark Murray <mark@grondar.za> To: "Jeroen C. van Gelderen" <jeroen@vangelderen.org> Cc: cvs-committers@FreeBSD.ORG, cvs-all@FreeBSD.ORG Subject: Re: cvs commit: src/sys/sys random.h src/sys/dev/randomdev randomdev.cyarrow.c Message-ID: <200007171743.TAA00707@grimreaper.grondar.za> In-Reply-To: <39732F7F.2E5BAEC0@vangelderen.org> ; from "Jeroen C. van Gelderen" <jeroen@vangelderen.org> "Mon, 17 Jul 2000 12:08:31 -0400." References: <39732F7F.2E5BAEC0@vangelderen.org>
next in thread | previous in thread | raw e-mail | index | archive | help
> Arbitrarily reseeding is bad in the case of Yarrow as it > allows for iterative guessing attacks. This is precisely why > this functionality is not described in the paper. Yarrow was > designed to manage the reseeding itself just to prevent this > kind of attack. Eh? Paragraph 5.4 of the paper begins: "The reseed control module determines when a reseed is to be performed. An explicit reseed occurs when some application explicitly asks for a reseed operation. This is intended to be used only rarely, and only by applications that generate very high-valued random secrets. Access to to the explicit reseed function should be restricted in many cases." The /dev/random device is mode 644; that should cover it. > You should definately run this kind of input trough the entropy > estimation routines and have Yarrow decide to reseed. You are > writing 4096 bytes anyway (on bootup) so this will (barring > serious bugs) trigger a reseed. If not, you just caught a bug > and the randomness device appears to not work. That's a good > thing. I disagree; this is the "explicit reseed" function, and as such, I reckon its design is OK. > If your entropy pool is compromised your attacker has root or > there is a serious bug in Yarrow. In both cases you will want > to take steps to prevent this from happening again... True. M -- Mark Murray Join the anti-SPAM movement: http://www.cauce.org To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200007171743.TAA00707>