Return-path: Received: from mail.eperm.de ([89.247.134.16]:48037 "EHLO mail.eperm.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752952AbbG2Gda (ORCPT ); Wed, 29 Jul 2015 02:33:30 -0400 From: Stephan Mueller To: Sandy Harris Cc: Oleksij Rempel , "Pan, Miaoqing" , "linville@tuxdriver.com" , "linux-wireless@vger.kernel.org" , Theodore Ts'o , linux-crypto@vger.kernel.org, nhorman@tuxdriver.com Subject: Re: [PATCH 2/2] ath9k: export HW random number generator Date: Wed, 29 Jul 2015 08:33:24 +0200 Message-ID: <2021681.UA65q8VJfQ@tauon.atsec.com> (sfid-20150729_083334_328216_78A57DE7) In-Reply-To: References: <1436946847-10909-1-git-send-email-miaoqing@qca.qualcomm.com> <3945775.m5HblJPgiO@tauon.atsec.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Sender: linux-wireless-owner@vger.kernel.org List-ID: Am Dienstag, 28. Juli 2015, 13:41:57 schrieb Sandy Harris: Hi Sandy, > >> However, the hwrandom framework does not provide any conditioning logic. > >At first sight, this sounds like a blunder to me, but I have not >looked at hwrandom at all. Is there a rationale? I think hwrandom is solely a framework to hook up RNG devices to user space. There is no massaging of data coming from the HW RNGs. Usually those HW RNGs all have their own conditioner and there is no need to do a conditioning again. > >For example, not building conditioning into that driver would make >perfect sense if the output were just being fed into the random(4) >which does plenty of mixing. The only problem then would be to make >sure of giving random(4) reasonable entropy estimates. hwrandom *may* be used to feed into the entropy pools. But there is no technical guarantee for that. Furthermore, I have seen use cases where the output of hwrandom is used for other purposes. Ciao Stephan