From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from v1.tansi.org (mail.tansi.org [84.19.178.47]) by mail.server123.net (Postfix) with ESMTP for ; Thu, 14 Nov 2019 00:16:28 +0100 (CET) Received: from gatewagner.dyndns.org (81-6-44-245.init7.net [81.6.44.245]) by v1.tansi.org (Postfix) with ESMTPA id DF0C11401E7 for ; Thu, 14 Nov 2019 00:16:18 +0100 (CET) Date: Thu, 14 Nov 2019 00:16:26 +0100 From: Arno Wagner Message-ID: <20191113231626.GA10948@tansi.org> References: <14224469d70c38f8c34baf4e2f750d4089993ab6@webmail> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Disposition: inline Content-Transfer-Encoding: quoted-printable In-Reply-To: <14224469d70c38f8c34baf4e2f750d4089993ab6@webmail> Subject: Re: [dm-crypt] Two questions List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: dm-crypt@saout.de On Wed, Nov 13, 2019 at 19:42:55 CET, mgreger@cinci.rr.com wrote: > From Michael Kj=F6rling: >=20 > > Yes; it implies that the two volumes are encrypted using the same > master key (as well as being accessible using the same set of > passphrases), _and_ it makes it obvious that this is the case. >=20 > (Assume any detached header is absent) >=20 > Obvious by inspecting the raw encrypted drives? My concern is salt/iv > reuse for same sector #'s on multiple drives leading to information > leakage. >=20 > For example let's say two encrypted drives were mirrored. Using the > same master key would make it obvious they are mirrored, but no > additional information is leaked (other than that they are in fact > copies of each other). But more complex scenarios exist: RAID, LVM2 > headers, etc. Those other scenarios are the ones I am curious about. You may also have sectors in filesystems that are generally the same=20 and that would be obvious.=20 The simple answer is: If you care, then do not do this. Otherwise you do not care and it is not a problem. No amount of analysis will make this go away. Regards, Arno --=20 Arno Wagner, Dr. sc. techn., Dipl. Inform., Email: arno@wagner.name GnuPG: ID: CB5D9718 FP: 12D6 C03B 1B30 33BB 13CF B774 E35C 5FA1 CB5D 9718 ---- A good decision is based on knowledge and not on numbers. -- Plato If it's in the news, don't worry about it. The very definition of=20 "news" is "something that hardly ever happens." -- Bruce Schneier