Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754928AbaBRR4p (ORCPT ); Tue, 18 Feb 2014 12:56:45 -0500 Received: from mho-02-ewr.mailhop.org ([204.13.248.72]:41738 "EHLO mho-02-ewr.mailhop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754072AbaBRR4l (ORCPT ); Tue, 18 Feb 2014 12:56:41 -0500 X-Mail-Handler: Dyn Standard SMTP by Dyn X-Originating-IP: 108.39.110.144 X-Report-Abuse-To: abuse@dyndns.com (see http://www.dyndns.com/services/sendlabs/outbound_abuse.html for abuse reporting information) X-MHO-User: U2FsdGVkX19XcwPSynIpj4ZgrMezApwKnFpyzTtSacc= X-DKIM: OpenDKIM Filter v2.0.1 titan 19FB752BD4A Date: Tue, 18 Feb 2014 12:56:24 -0500 From: Jason Cooper To: Geert Uytterhoeven Cc: Arnd Bergmann , "linux-arm-kernel@lists.infradead.org" , Grant Likely , Jason Gunthorpe , "devicetree@vger.kernel.org" , Laura Abbott , Kees Cook , "linux-kernel@vger.kernel.org" , Rob Herring , Kumar Gala Subject: Re: [RFC/PATCH 0/3] Add devicetree scanning for randomness Message-ID: <20140218175624.GY7862@titan.lakedaemon.net> References: <1392168805-14200-1-git-send-email-lauraa@codeaurora.org> <201402121251.06280.arnd@arndb.de> <20140217155419.682F7C401D4@trevor.secretlab.ca> <1418981.0py7JxXCp8@wuerfel> <20140217182312.GV7862@titan.lakedaemon.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 17, 2014 at 10:07:50PM +0100, Geert Uytterhoeven wrote: > On Mon, Feb 17, 2014 at 7:23 PM, Jason Cooper wrote: > >> Could we use a faster hash function that scans the entire device tree and > >> then just feed the output of that into add_device_randomness? We probably > >> can't expect that there is a lot of entropy in the DT blob, so the > >> result wouldn't be all that different in terms of quality of the random > >> seed. > > > > I think it would be easier to identify the few attributes that differ > > from board to board (mac address, serial number, etc), and differ from > > boot to boot (random-seed, timestamp) and just extract and feed those > > in. > > Isn't identifying those (mostly) a manual process? > Calculating a fast hash is fully automatic. The list would be pretty short, and once created wouldn't likely change too often. But it really depends on the 'fast hash'. if the two methods have comparable speed, I'd definitely prefer the hash. Easier to maintain. thx, Jason. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/