From owner-freebsd-current Sun Jul 30 2:19: 2 2000 Delivered-To: freebsd-current@freebsd.org Received: from grimreaper.grondar.za (grimreaper.grondar.za [196.7.18.138]) by hub.freebsd.org (Postfix) with ESMTP id DC88437B61A; Sun, 30 Jul 2000 02:18:43 -0700 (PDT) (envelope-from mark@grondar.za) Received: from grimreaper.grondar.za (localhost [127.0.0.1]) by grimreaper.grondar.za (8.9.3/8.9.3) with ESMTP id LAA07595; Sun, 30 Jul 2000 11:18:48 +0200 (SAST) (envelope-from mark@grimreaper.grondar.za) Message-Id: <200007300918.LAA07595@grimreaper.grondar.za> To: Brian Fundakowski Feldman Cc: current@FreeBSD.org Subject: Re: randomdev entropy gathering is really weak References: In-Reply-To: ; from Brian Fundakowski Feldman "Sun, 30 Jul 2000 00:25:42 -0400." Date: Sun, 30 Jul 2000 11:18:48 +0200 From: Mark Murray Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG > Mark already stated that in *practicality*, Yarrow-BF-cbc-256 1.0 > (I guess that's the proper name for this :-) is complex enough and > generates good enough ouput. If you /really/ want to make the attack > on it much harder, how about this: if you're going to read 1024 bits > of entropy from Yarrow on /dev/random, you will request it all at once > and block just as the old random(4) used to block; the blocking can > occur at 256 bit intervals and sleep until there is a reseed. Waiting > to reseed for each read will ensure a much larger amount of "real" > entropy than it "maybe" happening at random times. This is a reversion to the count-entropy-and-block model which I have been fiercely resisting (and which argument I thought I had sucessfully defended). My solution is to get the entropy gathering at a high enough rate that this is not necessary. I also agreed to _maybe_ look at a re-engineer of the "old" code in a secure way if a decent algorithm could be found (I am reading some papers about this ATM). M -- Mark Murray Join the anti-SPAM movement: http://www.cauce.org To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message