From mboxrd@z Thu Jan 1 00:00:00 1970 From: Milan Broz Subject: Re: [PATCH] dm-crypt: disable block encryption with arc4 Date: Mon, 25 Jan 2010 19:39:11 +0100 Message-ID: <4B5DE54F.7050206@redhat.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-crypto-owner@vger.kernel.org To: Mikulas Patocka Cc: dm-devel@redhat.com, Alasdair G Kergon , linux-crypto@vger.kernel.org List-Id: dm-devel.ids On 01/25/2010 07:29 PM, Mikulas Patocka wrote: > Hi > > When using arc4 to encrypt a block device, the resulting device is > unreliable. It reads garbage. That's because arc4 is a stream cipher, if > you write something, it advances its state and if you attempt to decrypt > the same sector, it uses new state that is different. > > This patch disables the use of arc4 on block devices. arc4 again. it is simply not a block cipher:-) This should be solved inside cryptoAPI and not blacklist it in dm-crypt, see that thread http://article.gmane.org/gmane.linux.kernel.cryptoapi/3441 Milan