From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752891AbdLENsm convert rfc822-to-8bit (ORCPT ); Tue, 5 Dec 2017 08:48:42 -0500 Received: from mail.eperm.de ([89.247.134.16]:42766 "EHLO mail.eperm.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751255AbdLENsi (ORCPT ); Tue, 5 Dec 2017 08:48:38 -0500 From: Stephan Mueller To: =?utf-8?B?xYF1a2Fzeg==?= Stelmach Cc: Krzysztof Kozlowski , robh+dt@kernel.org, Herbert Xu , "David S. Miller" , Kukjin Kim , linux-crypto@vger.kernel.org, linux-samsung-soc@vger.kernel.org, linux-kernel@vger.kernel.org, m.szyprowski@samsung.com, b.zolnierkie@samsung.com Subject: Re: [RFC] crypto: exynos - Icrease the priority of the driver Date: Tue, 05 Dec 2017 14:48:35 +0100 Message-ID: <2500626.C7ppcC6VU6@tauon.chronox.de> In-Reply-To: <20171205124214.31263-1-l.stelmach@samsung.com> References: <20171205124214.31263-1-l.stelmach@samsung.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am Dienstag, 5. Dezember 2017, 13:42:14 CET schrieb Łukasz Stelmach: Hi Łukasz, > exynos-rng is one of many implementations of stdrng. With priority as > low as 100 it isn't selected, if software implementations (DRBG) are > available. What about using 300? The reason is the following: in the normal case, the software PRNGs have 100 (X9.31) and 200 (SP800-90A DRBG). Thus, in normal case, the hardware takes precedence. In FIPS mode, the DRBG prio is increased by 200. As in FIPS mode you must have a DRBG and assuming that the hardware does not implement a DRBG, the software DRBG should be used as otherwise you have a FIPS-problem. Ciao Stephan