From owner-freebsd-questions@FreeBSD.ORG Thu Jan 17 09:02:18 2008 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 3225316A419 for ; Thu, 17 Jan 2008 09:02:18 +0000 (UTC) (envelope-from marcs@draenor.org) Received: from mx.unseen.co.za (mx.unseen.co.za [192.96.96.11]) by mx1.freebsd.org (Postfix) with ESMTP id BF75313C461 for ; Thu, 17 Jan 2008 09:02:17 +0000 (UTC) (envelope-from marcs@draenor.org) Received: from marcs by aztec.co.za with local (Exim 4.34) id 1JFQdW-0005Lo-AQ; Thu, 17 Jan 2008 11:02:10 +0200 Date: Thu, 17 Jan 2008 11:02:10 +0200 From: Marc Silver To: Wojciech Puchar Message-ID: <20080117090210.GD12470@draenor.org> References: <478F0D5A.9090107@highperformance.net> <20080117081414.GB12470@draenor.org> <478F1049.3000706@boosten.org> <20080117083837.GC12470@draenor.org> <20080117094332.K1563@wojtek.tensor.gdynia.pl> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080117094332.K1563@wojtek.tensor.gdynia.pl> User-Agent: Mutt/1.3.28i X-PGP-Key: http://draenor.org/pubkey.asc Cc: "Jason C. Wells" , freebsd general questions , Peter Boosten Subject: Re: Gutman Method on Empty Space X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 17 Jan 2008 09:02:18 -0000 Hi there, On Thu, Jan 17, 2008 at 09:43:46AM +0100, Wojciech Puchar wrote: > how? even single write is enough Not according to the paper that Gutmann wrote: http://www.usenix.org/publications/library/proceedings/sec96/full_papers/gutmann/ In short, he says that if you know how the data itself was overwritten it can be recovered. If I recall, the DoD standard for the deletion of data is to overwrite it 3 times. Obviously it all comes down to how important the data is that you're removing, but a single write is not enough if the data needs to be disposed of 'securely'. Cheers, Marc