From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Andreas Schwab Newsgroups: gmane.emacs.bugs Subject: bug#13949: Aw: Re: bug#13949: fill-paragraph is buggy, but using MD5 is even more buggy Date: Mon, 28 Mar 2016 16:31:32 +0200 Message-ID: <87d1qehdx7.fsf@linux-m68k.org> References: <87r3euhozp.fsf@linux-m68k.org> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: ger.gmane.org 1459175545 16695 80.91.229.3 (28 Mar 2016 14:32:25 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Mon, 28 Mar 2016 14:32:25 +0000 (UTC) Cc: 13949@debbugs.gnu.org To: "Petros Travioli" Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Mon Mar 28 16:32:14 2016 Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1akYDG-0005kL-4H for geb-bug-gnu-emacs@m.gmane.org; Mon, 28 Mar 2016 16:32:14 +0200 Original-Received: from localhost ([::1]:41137 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1akYDF-0006gi-Ah for geb-bug-gnu-emacs@m.gmane.org; Mon, 28 Mar 2016 10:32:13 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:33102) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1akYD8-0006fP-F2 for bug-gnu-emacs@gnu.org; Mon, 28 Mar 2016 10:32:10 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1akYD4-0000W9-Ev for bug-gnu-emacs@gnu.org; Mon, 28 Mar 2016 10:32:06 -0400 Original-Received: from debbugs.gnu.org ([208.118.235.43]:45021) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1akYD4-0000W5-B5 for bug-gnu-emacs@gnu.org; Mon, 28 Mar 2016 10:32:02 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1akYD4-0001ue-6j for bug-gnu-emacs@gnu.org; Mon, 28 Mar 2016 10:32:02 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Andreas Schwab Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Mon, 28 Mar 2016 14:32:02 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 13949 X-GNU-PR-Package: emacs X-GNU-PR-Keywords: Original-Received: via spool by 13949-submit@debbugs.gnu.org id=B13949.14591754957319 (code B ref 13949); Mon, 28 Mar 2016 14:32:02 +0000 Original-Received: (at 13949) by debbugs.gnu.org; 28 Mar 2016 14:31:35 +0000 Original-Received: from localhost ([127.0.0.1]:42148 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1akYCd-0001tz-Db for submit@debbugs.gnu.org; Mon, 28 Mar 2016 10:31:35 -0400 Original-Received: from mail-out.m-online.net ([212.18.0.9]:34596) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1akYCc-0001tr-DJ for 13949@debbugs.gnu.org; Mon, 28 Mar 2016 10:31:34 -0400 Original-Received: from frontend01.mail.m-online.net (unknown [192.168.8.182]) by mail-out.m-online.net (Postfix) with ESMTP id 3qYbv96YxZz3hjQq; Mon, 28 Mar 2016 16:31:33 +0200 (CEST) Original-Received: from localhost (dynscan1.mnet-online.de [192.168.6.68]) by mail.m-online.net (Postfix) with ESMTP id 3qYbv9666jzvPt1; Mon, 28 Mar 2016 16:31:33 +0200 (CEST) X-Virus-Scanned: amavisd-new at mnet-online.de Original-Received: from mail.mnet-online.de ([192.168.8.182]) by localhost (dynscan1.mail.m-online.net [192.168.6.68]) (amavisd-new, port 10024) with ESMTP id 7Ecf-6PqAnFo; Mon, 28 Mar 2016 16:31:32 +0200 (CEST) X-Auth-Info: DEnvpO0oHq0gIKJV8XhD1If5OQFt+pQXuteoEaEc8/G0J7DF2AVlBcHJNWY7XSdX Original-Received: from igel.home (ppp-88-217-16-153.dynamic.mnet-online.de [88.217.16.153]) by mail.mnet-online.de (Postfix) with ESMTPA; Mon, 28 Mar 2016 16:31:32 +0200 (CEST) Original-Received: by igel.home (Postfix, from userid 1000) id 7F93E2C38EB; Mon, 28 Mar 2016 16:31:32 +0200 (CEST) X-Yow: But was he mature enough last night at the lesbian masquerade? In-Reply-To: (Petros Travioli's message of "Mon, 28 Mar 2016 15:29:19 +0200") User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.0.92 (gnu/linux) X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 208.118.235.43 X-BeenThere: bug-gnu-emacs@gnu.org List-Id: "Bug reports for GNU Emacs, the Swiss army knife of text editors" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Original-Sender: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.bugs:115642 Archived-At: "Petros Travioli" writes: >> > But that's exactly what happens when you are using hash functions to >> > verify buffer equality, just with a more complicated mathematical >> > formulation and at a slightly different scale. >> > >> > So don't use hash functions to a two-sided correct answer to test buffer >> > equality. For a one-sided answer (if hash(x) != hash(y) then x != y), you >> > are fine. >> >> There is a difference between a hash function and a cryptographic hash >> function. An inportant property of a cryptographic hash function is the >> avalanche effect, that means a small change in the plaintext will result >> in a big change in the hash value. That makes such a hash function >> suitable for the reverse condition x != y => hash(x) != hash(y), with a >> very high probability of being true. >> > So far most old crypto functions have been broken. There is no doubt this will happen to any newer one sooner or later. If any single person would lose his work because of a random collision, this is an argument agains crypto hash functions. This is irrelevant. See avalanche effect. Andreas. -- Andreas Schwab, schwab@linux-m68k.org GPG Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5 "And now for something completely different."