From owner-freebsd-fs@FreeBSD.ORG Fri Jul 15 09:24:22 2005 Return-Path: X-Original-To: freebsd-fs@freebsd.org Delivered-To: freebsd-fs@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 2EAF416A41C; Fri, 15 Jul 2005 09:24:22 +0000 (GMT) (envelope-from phk@phk.freebsd.dk) Received: from haven.freebsd.dk (haven.freebsd.dk [130.225.244.222]) by mx1.FreeBSD.org (Postfix) with ESMTP id C9F1B43D48; Fri, 15 Jul 2005 09:24:21 +0000 (GMT) (envelope-from phk@phk.freebsd.dk) Received: from phk.freebsd.dk (unknown [192.168.48.2]) by haven.freebsd.dk (Postfix) with ESMTP id 7371EBC83; Fri, 15 Jul 2005 09:24:19 +0000 (UTC) To: David Kreil From: "Poul-Henning Kamp" In-Reply-To: Your message of "Thu, 14 Jul 2005 21:37:36 BST." <200507142037.j6EKbaf12941@parrot.ebi.ac.uk> Date: Fri, 15 Jul 2005 11:24:18 +0200 Message-ID: <9297.1121419458@phk.freebsd.dk> Sender: phk@phk.freebsd.dk Cc: freebsd-fs@freebsd.org, Poul-Henning Kamp , freebsd-questions@freebsd.org Subject: Re: gbde blackening feature - how can on disk keys be "destroyed" thoroughly? X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 15 Jul 2005 09:24:22 -0000 In message <200507142037.j6EKbaf12941@parrot.ebi.ac.uk>, David Kreil writes: > >Dear Poul-Henning, > >After a job induced pause in my strong interest in encryption solutions, >I have on my return tried to learn what has since changed with gbde. I must > be missing the obvious because I cannot locate a "changelog" or "release > notes" document. Not much has happened :-) In FreeBSD you need to study the cvs logs to see what happened. http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/geom/bde/?hideattic=0 >You have been most helpful in our discussion last year. I have now, in >particular, been wondering whether you have since at all had a chance of >revisiting the issue of blackening keys with multiple physical random >overwrite before resetting them to zero to avoid key recovery by methods >as available from companies like www.dataclinic.co.uk. I have talked with some people from various disk manufactureres who know what they talk about and their unanimous advice is: "forget it". The geometry of modern disk R/W heads does not allow you to do anything which will be really efficient. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.