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[23.128.96.18]) by mx.google.com with ESMTP id r26si1381179edq.99.2020.05.20.05.12.33; Wed, 20 May 2020 05:12:58 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-crypto-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=fail header.i=@chronox.de header.s=strato-dkim-0002 header.b=loekasaQ; spf=pass (google.com: domain of linux-crypto-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-crypto-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726546AbgETML6 (ORCPT + 99 others); Wed, 20 May 2020 08:11:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34674 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726452AbgETMLt (ORCPT ); Wed, 20 May 2020 08:11:49 -0400 Received: from mo6-p02-ob.smtp.rzone.de (mo6-p02-ob.smtp.rzone.de [IPv6:2a01:238:20a:202:5302::6]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B0B27C061A0E; Wed, 20 May 2020 05:11:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; t=1589976702; s=strato-dkim-0002; d=chronox.de; h=References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: X-RZG-CLASS-ID:X-RZG-AUTH:From:Subject:Sender; bh=dxK4Z+9yHO4jSPBzrsgC+jQ7JJM6/ROZjhK04+QSi/s=; b=loekasaQ58kKtS65SiEgMbCExdrlarRrN2LXfhbvpn916/r1eY32+fzUCo//cbUcVp PUjksE3TEAorh4s8NRDzCaM6bh2Hb9RQx2D1mse4PLSNVsHwQkIwvGYLpurfvQ/cvxnl 0qhRBSJFGf26sj81y95Mgz6JnpgbesXgZ+ufVjDpkltvmBPocQAkqGNTQL8hA95QGa2C 62CsSCriKHIcp0YW/0WoYwI45TsH6KRUU6f+tGOcdXdk1FgKo1C0jn7ie5v4OcjTZRBd YKZPp9/PY7YBytHFXTP9+gcA0+ggPx3aREDNYCqzIXUhiTz8NSKVYMgzk4S6Tbt02+2z BpLg== X-RZG-AUTH: ":P2ERcEykfu11Y98lp/T7+hdri+uKZK8TKWEqNyiHySGSa9k9xmwdNnzGHXPbI/Sc5g==" X-RZG-CLASS-ID: mo00 Received: from tauon.chronox.de by smtp.strato.de (RZmta 46.7.0 DYNA|AUTH) with ESMTPSA id k09005w4KCBZ5LX (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256 bits)) (Client did not present a certificate); Wed, 20 May 2020 14:11:35 +0200 (CEST) From: Stephan Mueller To: Krzysztof Kozlowski Cc: Lukasz Stelmach , Matt Mackall , Herbert Xu , Arnd Bergmann , Greg Kroah-Hartman , Ray Jui , Scott Branden , bcm-kernel-feedback-list@broadcom.com, Kukjin Kim , Florian Fainelli , Markus Elfring , Matthias Brugger , Stefan Wahren , linux-crypto@vger.kernel.org, linux-arm-kernel@lists.infradead.org, "linux-kernel@vger.kernel.org" , "linux-samsung-soc@vger.kernel.org" , Bartlomiej Zolnierkiewicz Subject: Re: [PATCH v2 1/2] hwrng: iproc-rng200 - Set the quality value Date: Wed, 20 May 2020 14:11:34 +0200 Message-ID: <3322411.JsYv2Y6bm7@tauon.chronox.de> In-Reply-To: References: <15745285.MnsZKaK4VV@tauon.chronox.de> <2041475.ybOAuNAZB8@tauon.chronox.de> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-crypto-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org Am Mittwoch, 20. Mai 2020, 14:00:01 CEST schrieb Krzysztof Kozlowski: Hi Krzysztof, > On Wed, 20 May 2020 at 13:53, Stephan Mueller wrote: > > > > That said, the illustrated example is typical for hardware RNGs. Yet > > > > it is never guaranteed to work that way. Thus, if you can point to > > > > architecture documentation of your specific hardware RNGs showing that > > > > the data read from the hardware is pure unconditioned noise data, then > > > > I have no objections to the patch. > > > > > > I can tell for sure that this is the case for exynos-trng[1]. > > > > So you are saying that the output for the exynos-trng is straight from a > > ring oscillator without any post-processing of any kind? > > Hi, > > I think we will never be able to state this because the manual is > quite limited in sharing internals. What the driver does and probably > Lukasz wanted to say is that there is "post processing" block and > feature which can be disabled. The manual is saying the TRNG block > generates random data from thermal noise but not how much in a direct > way. There could be some simple post-processing or not (except the one > able to on/off). Also manual says this post processing block is there > to remove statistical weakness from the TRNG block. To me it does not > prove enough that raw data is really raw... Unterstood, but can't that statement be added to the commit message? > > Best regards, > Krzysztof Ciao Stephan