From: LABBE Corentin Subject: Re: [PATCH] nvmem: sunxi-sid: SID content is not a valid source of randomness Date: Fri, 28 Oct 2016 14:37:20 +0200 Message-ID: <20161028123720.GA10889@Red> References: <1477144408-15896-1-git-send-email-clabbe.montjoie@gmail.com> <20161024201020.h6akyqad2o42xkhq@lukather> <20161025053855.GA901@Red> <20161025090634.3dae9ad52ae8382dde6af4c8@free.fr> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org, wens@csie.org, srinivas.kandagatla@linaro.org, linux-crypto@vger.kernel.org, Maxime Ripard , linux-arm-kernel@lists.infradead.org To: Jean-Francois Moine Return-path: Content-Disposition: inline In-Reply-To: <20161025090634.3dae9ad52ae8382dde6af4c8@free.fr> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org List-Id: linux-crypto.vger.kernel.org On Tue, Oct 25, 2016 at 09:06:34AM +0200, Jean-Francois Moine wrote: > On Tue, 25 Oct 2016 07:38:55 +0200 > LABBE Corentin wrote: > > > > On Sat, Oct 22, 2016 at 03:53:28PM +0200, Corentin Labbe wrote: > > > > Since SID's content is constant over reboot, > > > > > > That's not true, at least not across all the Allwinner SoCs, and > > > especially not on the A10 and A20 that this driver supports. > > > > > > > On my cubieboard2 (A20) > > hexdump -C /sys/devices/platform/soc\@01c00000/1c23800.eeprom/sunxi-sid0/nvmem > > 00000000 16 51 66 83 80 48 50 72 56 54 48 48 03 c2 75 72 |.Qf..HPrVTHH..ur| > > 00000010 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| > > * > > 00000100 16 51 66 83 80 48 50 72 56 54 48 48 03 c2 75 72 |.Qf..HPrVTHH..ur| > > 00000110 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| > > * > > 00000200 > > cubiedev ~ # reboot > > cubiedev ~ # hexdump -C /sys/devices/platform/soc\@01c00000/1c23800.eeprom/sunxi-sid0/nvmem > > 00000000 16 51 66 83 80 48 50 72 56 54 48 48 03 c2 75 72 |.Qf..HPrVTHH..ur| > > 00000010 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| > > * > > 00000100 16 51 66 83 80 48 50 72 56 54 48 48 03 c2 75 72 |.Qf..HPrVTHH..ur| > > 00000110 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| > > * > > 00000200 > > > > So clearly for me its constant. > > Even after power off/power on? Yes, even after remove of any power supply.