From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.devel Subject: Re: Can watermarking Unicode text using invisible differences sneak through Emacs, or can Emacs detect it? Date: Wed, 19 Jan 2022 13:43:19 +0200 Message-ID: <837dawt0h4.fsf@gnu.org> References: <87sftk49ih.fsf@yahoo.com> Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="28432"; mail-complaints-to="usenet@ciao.gmane.io" Cc: luangruo@yahoo.com, rms@gnu.org, emacs-devel@gnu.org To: Phil Sainty Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Wed Jan 19 12:55:04 2022 Return-path: Envelope-to: ged-emacs-devel@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 1nA9YN-00078h-Te for ged-emacs-devel@m.gmane-mx.org; Wed, 19 Jan 2022 12:55:04 +0100 Original-Received: from localhost ([::1]:50980 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nA9YM-00005b-Ig for ged-emacs-devel@m.gmane-mx.org; Wed, 19 Jan 2022 06:55:02 -0500 Original-Received: from eggs.gnu.org ([209.51.188.92]:59834) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nA9NL-00071b-JL for emacs-devel@gnu.org; Wed, 19 Jan 2022 06:43:42 -0500 Original-Received: from [2001:470:142:3::e] (port=34070 helo=fencepost.gnu.org) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nA9NK-0003B4-Tu; Wed, 19 Jan 2022 06:43:38 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=gnu.org; s=fencepost-gnu-org; h=References:Subject:In-Reply-To:To:From:Date: mime-version; bh=9IWiYYQS/oyzMXk+ODhJ6xG/LdQQHlxpYzKJOVJp6aU=; b=IUI2tTuZKNgy 4/zA7w1uVmEN5VHRltqhwXmbR1sJsf6l388pxqFmEXHx57tAUoi4rUBqv71g+ZLxKPBSB9/Frjt1r snzbD6g94HaG6nAnvJC5US9k5okjK2rm8+kiZ67xHd2d10zdlzTl8PKtyEjghOoxFCNrV4qs7W5eH axxXIqgztevRWt38k5788w/Dp1SZ1J2d/zNm5ipspZK1+yf8tgnYhKzPYgwtaAN7sUej4hcFOtDLZ jQcdg5Bp28Ng25HHyKkHAzy9W5rb2wUeckJ2RRk53Go+DYI797oQHZc6Jy+Lem1COrXDBea6LAWgH gA39kzI+QN2LuZlOULAeQA==; Original-Received: from [87.69.77.57] (port=4423 helo=home-c4e4a596f7) by fencepost.gnu.org with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nA9N5-0004yQ-LE; Wed, 19 Jan 2022 06:43:25 -0500 In-Reply-To: (message from Phil Sainty on Wed, 19 Jan 2022 23:05:51 +1300) X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.io gmane.emacs.devel:284971 Archived-At: > Date: Wed, 19 Jan 2022 23:05:51 +1300 > From: Phil Sainty > Cc: Richard Stallman , emacs-devel@gnu.org > > On 2022-01-19 17:47, Po Lu wrote: > > I think the "zero width characters" alluded to are displayed > > by Emacs as 1 pixel wide spaces > > You can highlight them like so: > > (set-face-background 'glyphless-char "red") > > I've had that configured ever since > https://debbugs.gnu.org/cgi/bugreport.cgi?bug=31194#40 > > If you're not expecting zero-width characters in text in general, > I think it's a good setting. Users and readers of certain scripts cannot use such a simplistic solution, which is basically only suitable for plain ASCII text. (And even there it is slowly becoming inappropriate, what with the growing popularity of ligatures, let alone Emoji.) Emacs should be able to do better.