From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Yuri Khan Newsgroups: gmane.emacs.help Subject: Re: Noob dumb question (extending emacs) Date: Sat, 23 Oct 2021 17:46:18 +0700 Message-ID: References: <86k0i6uoxd.fsf@duenenhof-wilhelm.de> <871r4ernmt.fsf@zoho.eu> <87o87hnrpt.fsf@zoho.eu> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="16258"; mail-complaints-to="usenet@ciao.gmane.io" To: Yuri Khan , Emanuel Berg , help-gnu-emacs Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Sat Oct 23 12:46:58 2021 Return-path: Envelope-to: geh-help-gnu-emacs@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1meEYE-0003zd-5f for geh-help-gnu-emacs@m.gmane-mx.org; Sat, 23 Oct 2021 12:46:58 +0200 Original-Received: from localhost ([::1]:58958 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1meEYC-0007Qv-SR for geh-help-gnu-emacs@m.gmane-mx.org; Sat, 23 Oct 2021 06:46:56 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:39410) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1meEXq-0007QT-7v for help-gnu-emacs@gnu.org; Sat, 23 Oct 2021 06:46:34 -0400 Original-Received: from mail-ua1-x930.google.com ([2607:f8b0:4864:20::930]:34624) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1meEXo-00058e-Bd for help-gnu-emacs@gnu.org; Sat, 23 Oct 2021 06:46:33 -0400 Original-Received: by mail-ua1-x930.google.com with SMTP id h4so12492570uaw.1 for ; Sat, 23 Oct 2021 03:46:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :content-transfer-encoding; bh=L1VaduAXj1ttdc/MFK0E5SEOuhD+ees1tDynuyTYttw=; b=fmZ1TRYuzrqYN4FjDiZNIZHW0XIMkuYJYTkSRhYoX/t/FbH4R6JeTEpqKa9xgJXB/m sx0NmkQdHU1dWE2jYFz4Ym9u/lFAiSd5drOdCUqK8V1mSrCUxN9xpZP0r7PEIET7GUB9 sXpIBuRPMG+MJPd7+n1uuN0/SZU1ke21RmiOp44XG0L8gsDrZ43j0KMDzzCHO5q9mxVe S+E4SQZfEUn3Gk7oVie7kY6OVXpLAtlLnQM7RIShG/iBxB4g9wrjUdSoVBI/MjWGOT6Y lyW32igAXkX2zrrrnMRz2cdir6utU0cCTP+x1SlRLmp9mfKz5zUIYRlWpW7tWJKVXB0I D47w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:content-transfer-encoding; bh=L1VaduAXj1ttdc/MFK0E5SEOuhD+ees1tDynuyTYttw=; b=PO9FEfBlS2g3llihWDGNiOBqbm9LtnxZYCoIPLOGRiGndzrLoZ4D7XtMpWILo2a8jb 1vzLGo3Tl6Qe2Ht+n4CfV17JOVyprmRJKsGTvvZ1frW4Kr3+1M3A1N8dAhB6XICq7wkd UGt8g1y5na5/Qlv+ETEa2eDvTEMAFJKviA6aiqNXnjcUKEJVkdhRzXu6uzepw+eEuV2L OX9tBUgk/SbNY+mvlVPiGNnwObcTlOjvYL0dAbzPzaV4ZryfbI+9TjO4ZiAmHl7w5QzJ mcOY1ur6Sdp9CbmZQiBSlrVI7VK0fZjkCS2DOk48c8VcMkfC2gQ9DMc7gpsCQO/48NLw QZDw== X-Gm-Message-State: AOAM5305c2Y5cA9SxKnK9Mfc6v4vqYaAnjbfWKQQeG2SLtoTTl6IzoDG RhnaHSjTFfMcDoQ8/qk9bfyyjaNDh70lDYsAaJo= X-Google-Smtp-Source: ABdhPJxMZYZJZ79ktjHONUFMWBhF6vsCFpeDjLwrlWogUOMqKzCYY02kwqPuombm5AUVPIb7B5IZscX6Xi6ukGentjw= X-Received: by 2002:ab0:5b03:: with SMTP id u3mr5529106uae.41.1634985990306; Sat, 23 Oct 2021 03:46:30 -0700 (PDT) In-Reply-To: Received-SPF: pass client-ip=2607:f8b0:4864:20::930; envelope-from=yurivkhan@gmail.com; helo=mail-ua1-x930.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Users list for the GNU Emacs text editor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Original-Sender: "help-gnu-emacs" Xref: news.gmane.io gmane.emacs.help:134045 Archived-At: On Sat, 23 Oct 2021 at 04:35, Jean Louis wrote: > - I have noticed that file "/proc/pressure/io" is constantly > changing, could not find temperature stuff now, thus: =E2=80=9CConstantly changing=E2=80=9D does not mean it is a reliable source= of randomness (entropy). Also, the word =E2=80=9Cpressure=E2=80=9D there does not refer to any physi= cal processes. In context, it is a metaphor, referring to the concurrent processes in your computer competing for a resource, in this case, the input/output system. Anyway: $ cat /proc/pressure/io some avg10=3D0.00 avg60=3D0.00 avg300=3D0.05 total=3D313213969 full avg10=3D0.00 avg60=3D0.00 avg300=3D0.04 total=3D238002455 $ cat /proc/pressure/io some avg10=3D0.13 avg60=3D1.09 avg300=3D1.08 total=3D318142202 full avg10=3D0.13 avg60=3D0.98 avg300=3D0.97 total=3D242407828 What we have here is some constant text that does not contribute to randomness in any way, and a few decimal numbers. A single sampling gives you 36 digits. 3 decimal digits =E2=89=88 10 bits, so you could estim= ate 120 bits which would be considered a fair amount of entropy. However, if you sample it repeatedly, as you would when generating a number of passwords, you can observe they are not completely independent. The moving averages over 10/60/300 seconds are continuous functions, i.e. the next sample is a value reasonably close to the previous; and the total is a monotonically and not very rapidly rising function, so the next sample is equal to the previous plus a small value. So the added entropy for each next sample is much smaller than the original 120 bits. (Of course you could just replicate what pwgen does, and read from /dev/urandom or /dev/random, and directly convert that into characters usable in passwords.)