From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joe Korty Subject: Re: [PATCH] Re: [PATCH] drivers/net: remove network drivers' last few uses of IRQF_SAMPLE_RANDOM Date: Sun, 18 May 2008 08:57:59 -0400 Message-ID: <20080518125759.GA18812@tsunami.ccur.com> References: <20080516105635.6cb1f505@core> <482D5FC5.2070103@firstfloor.org> <20080516121239.GA9627@gondor.apana.org.au> <482DB568.1040704@firstfloor.org> <20080517010136.GA15102@gondor.apana.org.au> <482EBAA8.3040506@firstfloor.org> <20080517130535.02d45372@infradead.org> <4830014F.9040800@firstfloor.org> <20080518112657.GK16496@mit.edu> Reply-To: Joe Korty Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii To: Theodore Tso , Andi Kleen , Arjan van de Ven , Chris Peterson , Herbert Xu Received: from flusers.ccur.com ([12.192.68.2]:40837 "EHLO gamx.iccur.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753337AbYERNGp (ORCPT ); Sun, 18 May 2008 09:06:45 -0400 Content-Disposition: inline In-Reply-To: <20080518112657.GK16496@mit.edu> Sender: netdev-owner@vger.kernel.org List-ID: On Sun, May 18, 2008 at 07:26:57AM -0400, Theodore Tso wrote: > On Sun, May 18, 2008 at 12:13:35PM +0200, Andi Kleen wrote: > > We don't use it for most long term keys, e.g. ssh host keys. That is > > because even on high entropy systems /dev/random usually doesn't work > > during distribution installation because the system has not run long > > enough to collect significant entropy yet. > ... > Hence, if you don't think the system hasn't run long enough to collect > significant entropy, you need to distinguish between "has run long > enough to collect entropy which is causes the entropy credits using a > somewhat estimation system where we try to be conservative such that > /dev/random will let you extract the number of bits you need", and > "has run long enough to collect entropy which is unpredictable by an > outside attacker such that host keys generated by /dev/urandom really > are secure". > ... > If distributions really cared, they could very well introduce keyboard > banging as part of the install process; but no, being able to do an > unmanned, "turnkey" install is considered more important. That says > something about how much they care about security right there. If the World really cared about security, every cpu chip would supply a true source of random bits based on the sampling some easily accessable quantum on-chip state, such as the tiny fluctuations in current flow across a resistance. I suspect supplying this would be about as expensive as supplying a true TSC driven directly by the external clock -- that is, so close to zero as to not matter. Joe