From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 17 Aug 2001 17:19:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 17 Aug 2001 17:19:13 -0400 Received: from SNAP.THUNK.ORG ([216.175.175.173]:48132 "EHLO snap.thunk.org") by vger.kernel.org with ESMTP id ; Fri, 17 Aug 2001 17:19:04 -0400 Date: Fri, 17 Aug 2001 17:18:35 -0400 From: Theodore Tso To: Andreas Dilger Cc: Steve Hill , "Richard B. Johnson" , linux-kernel@vger.kernel.org Subject: Re: /dev/random in 2.4.6 Message-ID: <20010817171834.A24850@thunk.org> Mail-Followup-To: Theodore Tso , Andreas Dilger , Steve Hill , "Richard B. Johnson" , linux-kernel@vger.kernel.org In-Reply-To: <200108151713.f7FHDg0n013420@webber.adilger.int> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.3.15i In-Reply-To: <200108151713.f7FHDg0n013420@webber.adilger.int>; from adilger@turbolinux.com on Wed, Aug 15, 2001 at 11:13:41AM -0600 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 15, 2001 at 11:13:41AM -0600, Andreas Dilger wrote: > Note that network interrupts do NOT normally contribute to the entropy > pool. This is because of the _very_theoretical_ possibility that an > attacker can "control" the network traffic to such a precise extent as > to flush or otherwise contaminate the entropy from the pool by sending > packets with very precise intervals and generating interrupts so exactly > as to fill the entropy pool with known data. IMVHO, this is basically > impossible, as the attacker could not possibly control ALL of the network > traffic, and you could optionally define "safe" and "unsafe" interfaces > for terms of entropy. That's not the only attack, actually. The much simpler attack pathis for an attack to **observe** the network traffic to such a precise extent as to be able to guess what the entropy numbers are that are going into the pool. (Think: FBI's Carnivore). The one saving grace here is that in order to really do this well, the attacker would need to be sitting on the local area network to get the best and most precise timing numbers. You can argue that this is still a theoretical attack; but it's not quite so difficult as saying that the attacker has to "control" the network traffic. - Ted