From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Jimmy Yuen Ho Wong Newsgroups: gmane.emacs.devel Subject: Re: A couple of questions and concerns about Emacs network security Date: Sun, 8 Jul 2018 15:54:24 +0100 Message-ID: References: <83o9g2uhju.fsf@gnu.org> <20180705115826.73c1d95e@jabberwock.cb.piermont.com> <878t6lom8g.fsf@mouse.gnus.org> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" X-Trace: blaine.gmane.org 1531061562 17790 195.159.176.226 (8 Jul 2018 14:52:42 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sun, 8 Jul 2018 14:52:42 +0000 (UTC) Cc: Emacs-Devel devel To: Lars Ingebrigtsen Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Sun Jul 08 16:52:38 2018 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1fcB3E-0004XL-RO for ged-emacs-devel@m.gmane.org; Sun, 08 Jul 2018 16:52:36 +0200 Original-Received: from localhost ([::1]:37255 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fcB5M-0007Kj-14 for ged-emacs-devel@m.gmane.org; Sun, 08 Jul 2018 10:54:48 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:46935) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fcB5D-0007J1-8h for emacs-devel@gnu.org; Sun, 08 Jul 2018 10:54:40 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fcB5C-0001HU-8M for emacs-devel@gnu.org; Sun, 08 Jul 2018 10:54:39 -0400 Original-Received: from mail-io0-x230.google.com ([2607:f8b0:4001:c06::230]:33915) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1fcB5C-0001H7-2F for emacs-devel@gnu.org; Sun, 08 Jul 2018 10:54:38 -0400 Original-Received: by mail-io0-x230.google.com with SMTP id l7-v6so14877189ioj.1 for ; Sun, 08 Jul 2018 07:54:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=cP8HKv1YcYivNmqaubVAJH4oT1E8TqkeBeDuTIBkc7A=; b=G5Hqd1cImuyO/b+7C28H1q1M5qJ5TTCW23mQCkyL1K74GDMx/LMKNn1BSUGCMOPyfo VP9VPoWDUjiLMBGGjMNTrbPOeVVE5Rrfu93N4GgvRuAh/ufQeaTV9nU2iTKwdDRgRto6 w01Puw0+txbz77/vBIv2qc2RWZjxmxBC6l60HWH9zadzJpfTzDRJLZ1Qn1ZA5vXMOLT2 RzAaT+U+NoS/Nk1Hr9uY7gDX4S98yGmQTZPtpQLhBHZsdnDpB4Vmus5bYeTt8b6MffJk 9O6zUx9hjafEExdDZkHu/UyYHDcoI36654Mb6dXsV/d+fmbRNyjFjrIV3aIbhniZyoBB 5HJQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=cP8HKv1YcYivNmqaubVAJH4oT1E8TqkeBeDuTIBkc7A=; b=pxUsgPTY87xRL8SIH75eUcK2U/UYS5NgIU4XGlxiHVOhdHBk66KDEZ1NlcpJYSfI6m s5WDWgxOiKIwK840JjsgaW7BHlUIe+DJzkPmefFjGb6ljCWwDb6AEiam2XLlaN1So/dB EPzio5ea6CwUe4hJpLe/1dT4PkoxpmszABLQtpo4JMPgyo53xG2Hn8JpWBCEM6YP9Rbi eVJ5FOZ4aks3Amn62+HrXvOaGBdlcWGu9rGNjzIZ9DiyzJjCD7n5t7T0gNZLmPcPr+v5 o5Rjsz0vfiLMi2W7MIACCTn900fI5wZVhq2AxJdgfzlJWe6Mjyn8ojKoC3fc+RLJcDAr JP+g== X-Gm-Message-State: APt69E2cTdNWH27GlOXOWmRO3/66Fs+Fuu5UjfFPs5M2bnXUr6h16wrF vpopSQB8nhwb/L3PYLOw5GJMFnrpMpWSEuyFS1LQxQ== X-Google-Smtp-Source: AAOMgpeoMyc/v9RsFDpVd0aQVdJG6WXFqN55q3YD707e0CDlWVNtCz0y8Uu/XKdQTy7Lc9c1Y86lkzEZSA6t7Q2pa24= X-Received: by 2002:a6b:2092:: with SMTP id g140-v6mr14009205iog.167.1531061677269; Sun, 08 Jul 2018 07:54:37 -0700 (PDT) In-Reply-To: <878t6lom8g.fsf@mouse.gnus.org> X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2607:f8b0:4001:c06::230 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.21 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.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.org gmane.emacs.devel:227103 Archived-At: > > 1) I don't think the `paranoid' setting is security theatre. It's not a > useful setting for general browsing, but if your use case is that you > only use Emacs for, say, talking with your IMAP server, and that's it, > and you're worried that you may somehow end up talking with the wrong > server, and you're, er, paranoid (perhaps with good reason), then > that's the setting for you. > I still haven't heard of a "good reason" yet. If the checks are complete on the 'high level (i.e. checks for all known problems, including checking your cert for revocations with OCSP+CT+CRL, use of interceptable static RSA key exchange...), it would require some sort of zero-day to forge a cert. Honestly if you are in that kind of hostile environment, using Emacs to check your email directly without connecting to a VPN first is an absolutely horrible idea. If you are in that kind of environment, you would know it. > But, yes, as Eli says, `paranoid' should perhaps do more for non-TLS > connections. The question is "what", though, because there's no > fingerprint (beyond the host/port number) that we can use to verify > that a non-TLS connection is to a previously seen host. > Exactly. NSM can only warn you if you are establishing a cleartext connection, nothing else can be done. > > I thought that it set the minimum number of bits (like it says in the > last sentence), but it would use however many bits the server allows. > The first sentence seems to contradict this, and that this sets an > upper as well as lower bound on the number of bits, which is pretty > horrific, if that's the case... But I don't think it is, because > I get ":diffie-hellman-prime-bits 2047" when connecting to a DH host. > That's true, but there's still no reason to default `gnutls-min-prime-bits` to 256. If that's the default, presumably checking for DH prime bits > 1024 is a bug as NSM should let 256-bit DH prime go through. BTW, this bahavior pretty much we can default `gnutls-min-prime-bits` to nil with no problem at all as we haven't seen any bug complaining about NSM checking for DH prime bits > 1024 being too strict. I would suggest we move the defcustom groups of all GnuTLS options to NSM again to avoid further confusion.