From: Milan Broz Subject: Re: [PATCH 0/1] dm-integrity: integrity protection device-mapper target Date: Mon, 24 Sep 2012 15:47:02 +0200 Message-ID: <50606456.7020607@redhat.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, dm-devel@redhat.com, linux-crypto@vger.kernel.org To: Dmitry Kasatkin Return-path: Received: from mx1.redhat.com ([209.132.183.28]:32216 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754136Ab2IXNrL (ORCPT ); Mon, 24 Sep 2012 09:47:11 -0400 In-Reply-To: Sender: linux-crypto-owner@vger.kernel.org List-ID: On 09/24/2012 11:55 AM, Dmitry Kasatkin wrote: > Both dm-verity and dm-crypt provide block level integrity protection. This is not correct. dm-crypt is transparent block encryption target, where always size of plaintext == size of ciphertext. So it can provide confidentiality but it CANNOT provide integrity protection. We need extra space to store auth tag which dmcrypt cannot provide currently. > dm-integrity provides a lighter weight read-write block level integrity > protection for file systems not requiring full disk encryption, but > which do require writability. Obvious question: can be dm-verity extended to provide read-write integrity? I would prefer to use standard mode like GCM to provide both encryption and integrity protection than inventing something new. Milan