From owner-cvs-src@FreeBSD.ORG Sun Apr 11 01:40:12 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 588EE16A4CE; Sun, 11 Apr 2004 01:40:12 -0700 (PDT) Received: from storm.FreeBSD.org.uk (storm.FreeBSD.org.uk [194.242.157.42]) by mx1.FreeBSD.org (Postfix) with ESMTP id C030643D53; Sun, 11 Apr 2004 01:40:11 -0700 (PDT) (envelope-from mark@grondar.org) Received: from storm.FreeBSD.org.uk (Ugrondar@localhost [127.0.0.1]) i3B8e9V4054137; Sun, 11 Apr 2004 09:40:09 +0100 (BST) (envelope-from mark@grondar.org) Received: (from Ugrondar@localhost)i3B8e9I1054136; Sun, 11 Apr 2004 09:40:09 +0100 (BST) (envelope-from mark@grondar.org) X-Authentication-Warning: storm.FreeBSD.org.uk: Ugrondar set sender to mark@grondar.org using -f Received: from grondar.org (localhost [127.0.0.1])i3B8cRIn075336; Sun, 11 Apr 2004 09:38:28 +0100 (BST) (envelope-from mark@grondar.org) From: Mark Murray Message-Id: <200404110838.i3B8cRIn075336@grimreaper.grondar.org> To: Nate Lawson In-Reply-To: Your message of "Sat, 10 Apr 2004 15:55:42 PDT." <20040410155306.W58852@root.org> Date: Sun, 11 Apr 2004 09:38:27 +0100 Sender: mark@grondar.org X-Spam-Score: 4 (****) FROM_NO_LOWER,MSGID_FROM_MTA_SHORT X-Scanned-By: MIMEDefang 2.39 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 harvest.c hash.c hash.h nehemiah.c nehemiah.h probe.c randomdev.c 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: Sun, 11 Apr 2004 08:40:12 -0000 Nate Lawson writes: > > Cryptographic strength is of lesser importance here, as the key > > input is Very Nicely Random(tm), however AES's speed and spectral > > qualities make it a good choice. It is important to remember that > > the hash is purely there to destroy any trends/tendencies that the > > hardware generator may have, and for that purpose an LFSR may work > > just fine. The hash is a "Whitener", and its requirements here are > > that its output spectrum is flat. > > An LFSR is not a cryptographic hash function. Do not use one to implement > a PRNG. The input is 99% random. It follows that if the hash/whitener is done properly the output should be 99% random. LFSR was an illustration; the intent is to use AES. M -- Mark Murray iumop ap!sdn w,I idlaH