From owner-freebsd-current Sat Jul 22 8:31:48 2000 Delivered-To: freebsd-current@freebsd.org Received: from cypherpunks.ai (cypherpunks.ai [209.88.68.47]) by hub.freebsd.org (Postfix) with ESMTP id 770EB37B66C; Sat, 22 Jul 2000 08:31:45 -0700 (PDT) (envelope-from jeroen@vangelderen.org) Received: from vangelderen.org (grolsch.ai [209.88.68.214]) by cypherpunks.ai (Postfix) with ESMTP id 38DFD52; Sat, 22 Jul 2000 11:31:43 -0400 (AST) Message-ID: <3979BE5F.9FADF58A@vangelderen.org> Date: Sat, 22 Jul 2000 11:31:43 -0400 From: "Jeroen C. van Gelderen" X-Mailer: Mozilla 4.73 [en] (X11; I; Linux 2.2.12 i386) X-Accept-Language: en MIME-Version: 1.0 To: Kris Kennaway Cc: Mark Murray , current@FreeBSD.ORG Subject: Re: randomdev entropy gathering is really weak References: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Kris Kennaway wrote: > > On Sat, 22 Jul 2000, Mark Murray wrote: > > > Lots of references: Schneier's "Applied Cryptography" talks about > > using Good Hashes for crypto and Good Crypto for hashes. Schneier's > > site at www.counterpane.com will give you plenty. > > I havent been able to get my hands on Applied Cryptography, but I don't > recall seeing anything like this on the website. I'll check again. > > > The differnce with the old system and Yarrow is yarrow's self-recovery > > property; Yarrow screens its internal state from the ouside world > > very heavily, and provides enough perturbation of it from its > > copious :-) entropy harvesting to keep the state safe from compromise. > > Yeah, I know all this and agree that Yarrow makes a better /dev/urandom, > but it doesn't change the fact that Yarrow-256 is only good for 256 bits > of entropy between reseeding operations. You can pull all you want out of > it but will never get more than 256 bits until it reseeds. You don't care in practice, 256 bits are unguessable. If you do care, you load a different random module :-) Cheers, Jeroen -- Jeroen C. van Gelderen o _ _ _ jeroen@vangelderen.org _o /\_ _ \\o (_)\__/o (_) _< \_ _>(_) (_)/<_ \_| \ _|/' \/ (_)>(_) (_) (_) (_) (_)' _\o_ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message