From owner-cvs-src@FreeBSD.ORG Mon Apr 12 15:35:08 2004 Return-Path: Delivered-To: cvs-src@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id B5E9016A4CE for ; Mon, 12 Apr 2004 15:35:08 -0700 (PDT) Received: from root.org (root.org [67.118.192.226]) by mx1.FreeBSD.org (Postfix) with SMTP id 6EF8343D3F for ; Mon, 12 Apr 2004 15:35:08 -0700 (PDT) (envelope-from nate@root.org) Received: (qmail 71072 invoked by uid 1000); 12 Apr 2004 22:35:09 -0000 Date: Mon, 12 Apr 2004 15:35:09 -0700 (PDT) From: Nate Lawson To: Mark Murray In-Reply-To: <200404110746.i3B7kiIn075106@grimreaper.grondar.org> Message-ID: <20040412153153.I70759@root.org> References: <200404110746.i3B7kiIn075106@grimreaper.grondar.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII cc: cvs-src@FreeBSD.ORG cc: src-committers@FreeBSD.ORG cc: cvs-all@FreeBSD.ORG Subject: Re: cvs commit: src/sys/modules/random Makefile src/sys/dev/random randomdev.h randomdev_soft.c randomdev_soft.h yar X-BeenThere: cvs-src@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: CVS commit messages for the src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 12 Apr 2004 22:35:08 -0000 On Sun, 11 Apr 2004, Mark Murray wrote: > Nate Lawson writes: > > > Still, opinion seems to be in favour of further postprocessing, so I'll > > > do it. > > I haven't looked at the FreeBSD PRNG yet but why not seed Yarrow? > > Yarrow's entropy accumulation and PRNG generator parts are disconnected > (that is part of its point), so there is no connection between the > number of bytes harvested and the number of bytes supplied. This > makes a very long armoured pipeline between accumulation and issue, > which seems like overkill when the suppied entropy is 99% OK (far > better than Yarrow currently ever gets, BTW). > > [...] > > Yarrow is unsuitable for this purpose; it is a great generator when > you have a low-entropy environment and you need to protect against > attackers having potential knowledge of the inputs. * XSTORE is an unprivileged operation, users can call it all they want. * If your hardware fails undetectably somehow (101010101...), a single-source PRNG also fails. If we seed our existing PRNG which accepts multiple sources, it doesn't. I think Jacques said it best. All I'm asking is that we use a well-reviewed PRNG and as many entropy sources as possible, including this nice VIA part. -Nate