From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932837Ab2GFANJ (ORCPT ); Thu, 5 Jul 2012 20:13:09 -0400 Received: from moutng.kundenserver.de ([212.227.126.171]:50305 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932264Ab2GFANH (ORCPT ); Thu, 5 Jul 2012 20:13:07 -0400 Date: Fri, 6 Jul 2012 02:13:00 +0200 From: Johannes Goetzfried To: Henrique de Moraes Holschuh Cc: Herbert Xu , linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org Subject: Re: [PATCH] crypto: twofish-avx - remove useless instruction Message-ID: <20120706001300.GF2091@kronos.redsun> References: <20120705184358.GE2091@kronos.redsun> <20120705234612.GD29301@khazad-dum.debian.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120705234612.GD29301@khazad-dum.debian.net> User-Agent: Mutt/1.5.20 (2009-06-14) X-Provags-ID: V02:K0:vMFI2fcU+trjcwJ2FhpgiTPIk8ZdfYOFIjfrawgW4vQ DuDiTWe2subHH3ONLScJrb7W1OlncHQXx8G95No16gMoQqU7d1 +qTDq7nipafig9xa9fftQtL/ZHVTK/xUuvi8b1EuM7UsfFEVHZ SQ8D9ngdYJT2VBExlPr/RDosPx+gTzbYcw8/BaMF+iT/hVyi50 Z18hCoxrc+UHzlt3DrBEkt4cA6qxj5I0HBN8deWH0govgFbhUZ w2TFj7+Q2zNfvEafm2rBkUsSacFCAwOFYYddLGslYWnFXCD9tE VZVyPDI8Fro2qhvhLvU/8nIy4Ar8Lar8RuK1VWJEPqQj+UTG/X 9B4UE/VJgLSgzYYmtKes= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 05, 2012 at 08:46:12PM -0300, Henrique de Moraes Holschuh wrote: > Is it useless, or is it there to harden against some side-channel > attack? When writing this implementation, I first had a different approach with more data getting read in and I just forgot to delete this instruction in the end. The instruction didn't have any purpose regarding side-channel attacks. In the decryption routine the instruction has been correctly deleted in the same place.