From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from tansi.org (ns.km10532-04.keymachine.de [87.118.102.195]) by mail.saout.de (Postfix) with ESMTP for ; Thu, 19 Nov 2009 08:41:06 +0100 (CET) Received: from gatewagner.dyndns.org (84-74-164-239.dclient.hispeed.ch [84.74.164.239]) by tansi.org (Postfix) with ESMTP id D11884250002 for ; Thu, 19 Nov 2009 08:41:05 +0100 (CET) Date: Thu, 19 Nov 2009 08:41:05 +0100 From: Arno Wagner Message-ID: <20091119074104.GC8694@tansi.org> References: <4B032794.6090104@gmx.net> <20091118054555.GB28949@tansi.org> <4B03C5EE.7010702@gmx.net> <20091118102515.GB30910@tansi.org> <4B03D865.8070905@redhat.com> <4B03F5F2.9080609@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4B03F5F2.9080609@redhat.com> Subject: Re: [dm-crypt] different default key sizes for CREATE and LUKSFORMAT List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: dm-crypt@saout.de On Wed, Nov 18, 2009 at 02:26:10PM +0100, Milan Broz wrote: > On 11/18/2009 12:20 PM, Milan Broz wrote: > > For default LUKS header hash: > > > > - default is SHA1 > > > > switching to another (probably SHA-256?) means complete incompatibility > > with all cryptsetup <1.1.x, this need some time when all most distros > > use new cryptsetup. > > No need to hurry, there is no problem with SHA1 in this application > > of hash function. > > Also I think we can increase MK digest iterations > (default is now 10, increasing it to 1000 should not cause any performance > problems. Just make the possible attack to MK digest more complicated > if some hash is completely broken in future.) > > Does this make sense of it is not needed? If I understand this correctly, this is the "iteration-count" parameter to PBKDF2. If so, then RFC 2898 recommends a minimum count of 1000 anyways. This is hovever not protection against a broken hash, as even a very weak hash should be extremely hard to break when iterated 10 times. The main purpose of this parameter is to make exhaustive search more expensive. I think this should definitely go up to 1000. Arno -- Arno Wagner, Dr. sc. techn., Dipl. Inform., CISSP -- Email: arno@wagner.name GnuPG: ID: 1E25338F FP: 0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F ---- Cuddly UI's are the manifestation of wishful thinking. -- Dylan Evans If it's in the news, don't worry about it. The very definition of "news" is "something that hardly ever happens." -- Bruce Schneier