From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.io/gmane.emacs.gnus.general/88038 Path: news.gmane.org!.POSTED!not-for-mail From: Chris Marusich Newsgroups: gmane.emacs.gnus.general Subject: EFAIL: Never process a PGP message without a valid MDC Date: Thu, 31 May 2018 22:17:53 -0700 Message-ID: <87d0xbaxvi.fsf@gmail.com> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha256; protocol="application/pgp-signature" X-Trace: blaine.gmane.org 1527830228 20219 195.159.176.226 (1 Jun 2018 05:17:08 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Fri, 1 Jun 2018 05:17:08 +0000 (UTC) User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.3 (gnu/linux) To: ding@gnus.org Original-X-From: ding-owner+m36252@lists.math.uh.edu Fri Jun 01 07:17:04 2018 Return-path: Envelope-to: ding-account@gmane.org Original-Received: from mxfilter-048034.atla03.us.yomura.com ([107.189.48.34]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1fOcQx-00057z-HE for ding-account@gmane.org; Fri, 01 Jun 2018 07:17:03 +0200 X-Yomura-MXScrub: 1.0 Original-Received: from lists1.math.uh.edu (unknown [129.7.128.208]) by mxfilter-048034.atla03.us.yomura.com (Halon) with ESMTPS id 45ee3eba-655b-11e8-b9c7-b499baa2b07a; Fri, 01 Jun 2018 05:18:52 +0000 (UTC) Original-Received: from localhost ([127.0.0.1] helo=lists.math.uh.edu) by lists1.math.uh.edu with smtp (Exim 4.90_1) (envelope-from ) id 1fOcS7-00055E-L1; Fri, 01 Jun 2018 00:18:15 -0500 Original-Received: from mx2.math.uh.edu ([129.7.128.33]) by lists1.math.uh.edu with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from ) id 1fOcS2-00054g-JN for ding@lists.math.uh.edu; Fri, 01 Jun 2018 00:18:10 -0500 Original-Received: from quimby.gnus.org ([80.91.231.51]) by mx2.math.uh.edu with esmtps (TLSv1.2:ECDHE-RSA-AES128-GCM-SHA256:128) (Exim 4.90_1) (envelope-from ) id 1fOcS0-0007yB-El for ding@lists.math.uh.edu; Fri, 01 Jun 2018 00:18:10 -0500 Original-Received: from mail-pl0-f68.google.com ([209.85.160.68]) by new-quimby.gnus.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.84_2) (envelope-from ) id 1fOcRy-0006Cq-U8 for ding@gnus.org; Fri, 01 Jun 2018 07:18:07 +0200 Original-Received: by mail-pl0-f68.google.com with SMTP id i5-v6so14617173plt.2 for ; Thu, 31 May 2018 22:18:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:subject:user-agent:date:message-id:mime-version; bh=psceC4fj7WTCxh5QmEXIvzqCryhVvGdoQN0p/Lyn7RU=; b=dnOOUmuMj3pkVN8ZzHGg5d1zgYZ+xL+/mw4/5GfH4EmwK67eY0Vk862e1fMt8KPy2n QBxHzlT+u8wlIBCVIYmloE6RQJQu4ptrD/AFBXtqCPv5NkIZu6XzWHyn3r/8QoGU7q7N 6b38gf1Ua58jr5Db/3nydrVzy8TveS1g6DCo62l4EfmvhnjTOGUKAsO3nIyc/8mbHAfj 3hJAd82QUXsemnvBOaM1u4STFifTppK+1XQOSzzOMrneJzeNjxjHrHJ83HomgzZ1EG/a SUMTLGk8ZFQBDvzM/d/umXEADa9Hlmie4pDbZutzKE9Hmam+YZKHmy6EBsuC5Wm697Jj I6sA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:subject:user-agent:date:message-id :mime-version; bh=psceC4fj7WTCxh5QmEXIvzqCryhVvGdoQN0p/Lyn7RU=; b=VCDIKVGZPnvfktRd1XcNs2VVp3wwsvSyduSbWYjqTz18p9B+X9iTRASnb5ujXuDoPc Eyy3WdH2jCbOoDGSchoox/OEpcY9dBa+FbWAHyugxM0WVBt0I/RcOpsWspDAc9pYfiBH /ZMPNp3WOEwNXjMQgcJ7qT4O2OZXM7tJdWfKvdShUPYrI1bzRrfuS4OFElb/NNcZeuLw aqtQidLQGok22naO4qPIZjSuLFT9zNAy5dXXia0y/4oZF9vUXLmV6iGoe89n+X910rCd d26PEiZMpvBdIQj1DR7EMpcH5he4nGiLMz9Q8oVItGQJRK4m9BbspnWCGjE/r9/b1EDb i4PQ== X-Gm-Message-State: ALKqPwdaE26v9gxtvyumbgIqVAKjvcAFW7oq3UvxHVGOGtzRQdN+km4O Ajdzfpa8gmd3cNyTbkZLeu1mmg== X-Google-Smtp-Source: ADUXVKJLWjSuibm6ThJzjKXuXYjM4prQXRK1Ch7vzO3lkzni8/71dwAfda4g0WmtPwSBvbJnf2z/rw== X-Received: by 2002:a17:902:7244:: with SMTP id c4-v6mr9747481pll.265.1527830279352; Thu, 31 May 2018 22:17:59 -0700 (PDT) Original-Received: from garuda.local (c-24-18-253-84.hsd1.wa.comcast.net. [24.18.253.84]) by smtp.gmail.com with ESMTPSA id q24-v6sm8788045pfh.26.2018.05.31.22.17.57 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 31 May 2018 22:17:57 -0700 (PDT) X-Spam-Score: -2.0 (--) List-ID: Precedence: bulk Xref: news.gmane.org gmane.emacs.gnus.general:88038 Archived-At: --=-=-= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable Hi, I use Gnus for email. In light of EFAIL [1][2], I'm trying to use Gnus more securely. In their official response to EFAIL, the GnuPG team pointed out that the Modification Detection Code (MDC) feature of GnuPG can protect against this kind of attack when used correctly [3]. They recommend that you "check with your email plugin vendor to see if they handle MDC errors correctly". So here I am! I'd like to ensure that, when decrypting email, if the MDC is either (1) missing or (2) invalid, Gnus never processes the data in ways that expose me to the risk of an EFAIL-style attack. I understand that GnuPG emits a warning about the MDC in some cases (e.g., if a non-modern cipher algorithm is used without an MDC) and an error in others (e.g., if a modern cipher is used without an MDC) [4]. The messages apparently look like this: gpg: encrypted with 256-bit ECDH key, ID 7F3B7ED4319BCCA8, created 2017-0= 1-01 "Werner Koch " [GNUPG:] BEGIN_DECRYPTION [GNUPG:] DECRYPTION_INFO 0 7 [GNUPG:] PLAINTEXT 62 1526109594=20 [GNUPG:] PLAINTEXT_LENGTH 69 There is more to life than increasing its speed. -- Mahatma Gandhi gpg: WARNING: message was not integrity protected [GNUPG:] DECRYPTION_FAILED [GNUPG:] END_DECRYPTION In any case, until the MDC has been successfully validated, I don't want Gnus to do anything risky, such as displaying the article to me. What should I do to ensure that Gnus behaves the way I want? Footnotes:=20 [1] https://efail.de/ [2] https://www.eff.org/deeplinks/2018/05/not-so-pretty-what-you-need-know= -about-e-fail-and-pgp-flaw-0 [3] https://lists.gnupg.org/pipermail/gnupg-users/2018-May/060334.html [4] https://lists.gnupg.org/pipermail/gnupg-users/2018-May/060320.html =2D-=20 Chris --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEy/WXVcvn5+/vGD+x3UCaFdgiRp0FAlsQ1wEACgkQ3UCaFdgi Rp13YA/9Gt4no2BVGXv1eXG5Wii4jmGfPngMhq5gXAtUM3HCWI92XTtD4Vj3By3W 8vn4OrGRPyFJWpDTuRKeb6Nnci9xlxktD/1Ky5io+elZOKi9oZUvOyBO7wkL77is 6nF2nOGB7ZGnucyQOA4KfEYmG1PZwtx2ZBfGxV74/emACpNDCAjP1L1RKAN2+XhT kDWLVtYtUOvLsQdeYsGaBfQUlRDAZnIEbMlY8gfZOv1MYuIOqfgivcTM8Ycrz5DN s7b1/UnBL694jWMB4w1tWH4wIIGDJZlhoziCn7obr+GksvkkqAotdBQE7Sgc/mUU HHUz0S9psPh6BYmOgfslQYRAMJ/MN3nI8QKiU+eJfH4ROgqVDuuJ5Db0xJJI4N0+ 1eMr9O7+vneIF90M0APeeK8z5Uc7sDyPDsTbPYHOkcqRQ34nvBTtZ8eT1xSnfsBk 3oHTS2+BbGesgUY/mDBDSnByRuP/V+WaeQ+OhdCKK7GRAY4qnhMoZdRCkgx/0Iyw AzYyt6ddUWq2iJ0DZdGLe3KidsvW30lAiwvC4/1383ao3Un/nygwftNiFlS7pzMf 2sOzmc/f5PB7QKiMtrHkM6H659REPDlxsKNMaWzIPWNGpHpoNahtHz2AYcuzo7iJ zs15sQFMSM3YGQoGsmJ5YEKK3JeqAuIUPySbPpTPh4ENOb3NOW0= =chc7 -----END PGP SIGNATURE----- --=-=-=--