From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751834AbaEAQeO (ORCPT ); Thu, 1 May 2014 12:34:14 -0400 Received: from quartz.orcorp.ca ([184.70.90.242]:35665 "EHLO quartz.orcorp.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751337AbaEAQeN (ORCPT ); Thu, 1 May 2014 12:34:13 -0400 Date: Thu, 1 May 2014 10:34:07 -0600 From: Jason Gunthorpe To: Boris BREZILLON Cc: Brian Norris , David Woodhouse , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mtd@lists.infradead.org, Maxime Ripard , linux-arm-kernel@lists.infradead.org Subject: Re: [RFC PATCH 0/3] mtd: nand: add randomizer support Message-ID: <20140501163407.GB3296@obsidianresearch.com> References: <1398906592-24677-1-git-send-email-b.brezillon.dev@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1398906592-24677-1-git-send-email-b.brezillon.dev@gmail.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Broken-Reverse-DNS: no host name found for IP address 10.0.0.161 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 01, 2014 at 03:09:49AM +0200, Boris BREZILLON wrote: > Hello, > > This series is a proposal to add support for randomizers (either software > or hardware) to NAND flash controller drivers. FWIW, I think the term for reversibly combining a PRBS with data is 'scrambling', it is often used in communication systems for similar reasons - probabilisticly increasing transition density. randomizing is something else entirely :) BTW, there are security concerns here. The scrambler PRBS must not be predictable by the user, otherwise they can write data that undoes the scramble and defeat it, ie deliberately writing the last 2k of a 4k write block as all 0's after scrambling could cause the first 2k to be lost. That feels like something that could be scary .. Jason