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 16:10:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 17 Aug 2001 16:09:50 -0400 Received: from h24-64-71-161.cg.shawcable.net ([24.64.71.161]:59894 "EHLO webber.adilger.int") by vger.kernel.org with ESMTP id ; Fri, 17 Aug 2001 16:09:36 -0400 From: Andreas Dilger Date: Fri, 17 Aug 2001 14:09:43 -0600 To: "Mark H. Wood" Cc: linux-kernel@vger.kernel.org Subject: Re: ext2 not NULLing deleted files? Message-ID: <20010817140831.H17372@turbolinux.com> Mail-Followup-To: "Mark H. Wood" , linux-kernel@vger.kernel.org In-Reply-To: <20010817020241.C32617@turbolinux.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.3.20i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Aug 17, 2001 12:55 -0500, Mark H. Wood wrote: > Regarding the need to do more than just zero unwanted data, I note that > there is a U.S. DOD MIL-SPEC (no, I do not know the number) which defines > a sequence of patterns to be used for erasing magnetic media. In the Usenix paper quoted earlier in this thread (I believe) it was stated that the MIL-SPEC document was actually bogus. REAL secure deletion requirements were much more strict (something like 15 passes of various random and non-random patterns vs. 7 passes of alternating all 0 and all 1 data), but the US government made it think that the MIL-SPEC requirements were enough, so that naive users would follow it, still leaving enough trace data on the disk for the government to retrieve it. Still, even a single pass of zero writes is enough to prevent 99.9% of attackers from getting the data back. Cheers, Andreas -- Andreas Dilger \ "If a man ate a pound of pasta and a pound of antipasto, \ would they cancel out, leaving him still hungry?" http://www-mddsp.enel.ucalgary.ca/People/adilger/ -- Dogbert