From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C732CC352AA for ; Wed, 2 Oct 2019 12:01:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A127821783 for ; Wed, 2 Oct 2019 12:01:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728172AbfJBMBr (ORCPT ); Wed, 2 Oct 2019 08:01:47 -0400 Received: from outgoing-auth-1.mit.edu ([18.9.28.11]:46876 "EHLO outgoing.mit.edu" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725875AbfJBMBr (ORCPT ); Wed, 2 Oct 2019 08:01:47 -0400 Received: from callcc.thunk.org (guestnat-104-133-0-98.corp.google.com [104.133.0.98] (may be forged)) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id x92C1GcC011091 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 2 Oct 2019 08:01:17 -0400 Received: by callcc.thunk.org (Postfix, from userid 15806) id 0215B42088C; Wed, 2 Oct 2019 08:01:15 -0400 (EDT) Date: Wed, 2 Oct 2019 08:01:15 -0400 From: "Theodore Y. Ts'o" To: "Ahmed S. Darwish" Cc: Linus Torvalds , Thomas Gleixner , a.darwish@linutronix.de, LKML , Nicholas Mc Guire , the arch/x86 maintainers , Andy Lutomirski , Kees Cook Subject: Re: x86/random: Speculation to the rescue Message-ID: <20191002120115.GA13880@mit.edu> References: <20191001161448.GA1918@darwi-home-pc> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20191001161448.GA1918@darwi-home-pc> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 01, 2019 at 06:15:02PM +0200, Ahmed S. Darwish wrote: > > Using the "ent" tool, [2] also used to test randomness in the Stephen > Müller LRNG paper, on a 500000-byte file, produced the following > results: The "ent" tool is really, really useless. If you take any CRNG, even intialized with a known seed, "ent" will say that it's *GREAT*! If you don't believe me, disable all entropy inputs into the CRNG, initialize it with "THE NSA IS OUR LORD AND MASTER", and then run it. You'll get substantially the same results. (And if we didn't the Cha Cha 20 encryption algorithm would be totally broken). - Ted