From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mps1.wohnheimg.uni-frankfurt.de (mps1.wohnheimg.uni-frankfurt.de [141.2.118.239]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.server123.net (Postfix) with ESMTPS for ; Mon, 14 Mar 2016 22:24:26 +0100 (CET) Received: from p4fe842d6.dip0.t-ipconnect.de ([79.232.66.214] helo=[192.168.0.11]) (Authed sender Sven 'DarKRaveR' Eschenberg) by mps1.wohnheimg.uni-frankfurt.de via ESMTPSA (TLSv1.2:ECDHE-RSA-AES128-GCM-SHA256:128) (Exim) (envelope-from ) id 1afZyT-0004na-VA for dm-crypt@saout.de; Mon, 14 Mar 2016 22:24:26 +0100 References: <20160314152130.GF21198@redhat.com> <56E709E2.4010004@whgl.uni-frankfurt.de> <56E716EF.2080709@gmail.com> From: Sven Eschenberg Message-ID: <56E72C09.9000903@whgl.uni-frankfurt.de> Date: Mon, 14 Mar 2016 22:24:25 +0100 MIME-Version: 1.0 In-Reply-To: <56E716EF.2080709@gmail.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [dm-crypt] Some questions/clarifications around the LUKS spec List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: dm-crypt@saout.de Am 14.03.2016 um 20:54 schrieb Milan Broz: > On 03/14/2016 07:58 PM, Sven Eschenberg wrote: > > ... >> On a sidenote: When cryptsetup switched it's defaults to aes-xts it >> stopped being compliant to the (original) LUKS specs. No doubt. > ... >> Again cryptsetup gave up on the specs, as there was a severe need for >> these changes. It really had been wise to ditch the original on disk >> format at that time and create a new revised (sub)version of the on disk >> format. It did not happen though and currently the reference >> implementation is the 'de facto' specification, while the original spec >> is only the 'de jure' specification. But then again, 'industry' and >> 'practice' define standards, don't they? *SCNR* > > Sorry? Spec is updated, it mentions XTS mode, and disk format remains still the same, > despite I did last update in 2011. (Simply because there was no need to update > it.) I'll mention more in another reply. Updating a spec needs more than just mentioning something. Esp. changes may not be incompatible to previous revisions. If changes are incompatible, a new version is needed (instead of a simple revision). A change to the list of valid values as well as the change in offset calculation to meet alignment requirements are indeed incompatible to the original specification for the v1 header, like it or not. Thus, by introducing these changes, a new version of the on disk format was introduced and this should have been reflected by reversioning the header as well. Having multiple possible specs for the same magic+version is something one really should not go for. > > Cryptsetup never gave up specs, it is still compatible to the document. > > Milan Interesting *raising eyebrow* -Sven