From: Milan Broz Subject: Re: [dm-devel] Some thoughts about providing data block checksumming for ext4 Date: Wed, 05 Nov 2014 22:37:09 +0100 Message-ID: <545A9885.8070901@gmail.com> References: <20141103233308.GA27842@thunk.org> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Cc: linux-ext4@vger.kernel.org, dm-devel@redhat.com To: Mikulas Patocka , Theodore Ts'o Return-path: Received: from mail-la0-f43.google.com ([209.85.215.43]:56641 "EHLO mail-la0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751311AbaKEVhN (ORCPT ); Wed, 5 Nov 2014 16:37:13 -0500 Received: by mail-la0-f43.google.com with SMTP id ge10so1507138lab.2 for ; Wed, 05 Nov 2014 13:37:12 -0800 (PST) In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: On 11/05/2014 01:27 AM, Mikulas Patocka wrote: > So you really need cryptographic hashes instead of checksums to avoid the > collisions. I am not sure if it was mentioned but also see how integrity is implemented in FreeBSD GELI system by playing with sector sizes http://svnweb.freebsd.org/base/head/sys/geom/eli/g_eli_integrity.c?view=co Also, for encrypted devices (either on file level or block level) I think there are still requests for implementing real crypto authenticated modes (like GCM) which obviously need similar space for auth tag. (I think ZFS uses it this way.) Milan