Re: Emacs: Crypto: How to get automatic encryption?

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+From: Antoine =?utf-8?Q?Beaupr=C3=A9?= <anarcat@anarcat.ath.cx>\r
+To: Gregor Zattler <telegraph@gmx.net>, David Edmondson <dme@dme.org>,\r
+       Jameson Graef Rollins <jrollins@finestructure.net>,\r
+       Gregor Zattler <telegraph@gmx.net>, Notmuch Mail <notmuch@notmuchmail.org>\r
+Subject: Re: Emacs: Crypto: How to get automatic encryption?\r
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+Date: Tue, 17 Jan 2012 04:48:36 -0000\r
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+\r
+Jumping in here, I have modified the previously posted code here to\r
+provide me with a more complete solution.\r
+\r
+With the attach code, I can:\r
+\r
+ * automatically encrypt mails if all recipients have a *valid* public\r
+   key. The previous patch allowed encryption if a key existed but was\r
+   revoked, which cause a weird UX issue where the user would be\r
+   bothered with "No public key for..."\r
+\r
+ * not have specify if i want to encrypt the mail or not: it is\r
+   encrypted if possible\r
+\r
+ * try to autodetect (by running the function directly) if the mail will\r
+   be crypted and signed or just signed before sending\r
+\r
+ * explicitely request the mail to be encrypted or just signed, if I\r
+   want to, using the usual keybindings (ie. the existing #secure tags\r
+   are respected)\r
+\r
+So basically, this replaces the common hook:\r
+\r
+(add-hook 'message-setup-hook 'mml-secure-sign-pgpmime)\r
+\r
+with this:\r
+\r
+(add-hook 'message-send-hook 'anarcat/message-set-encryption)\r
+\r
+The rationale behind this technique is that the setup-hook runs when\r
+recipients are not yet defined so it will always set the mail to be only\r
+signed, even though your final recipients should be crypted.=20\r
+\r
+An alternative would be for notmuch to prompt the To: header before\r
+setting up the buffer ("=C3=A0 la" Mutt), but I didn't feel like going that\r
+way.\r
+\r
+Code is attached. Obviously, those function names would change if they\r
+would be to integrate into notmuch. ;)\r
+\r
+\r
+--=-=-=\r
+Content-Type: application/emacs-lisp\r
+Content-Disposition: inline; filename=notmuch-opportunistic.el\r
+Content-Transfer-Encoding: quoted-printable\r
+\r
+;; -*- mode: emacs-lisp; -*-\r
+\r
+(require 'notmuch)\r
+\r
+(add-hook 'message-send-hook 'anarcat/message-set-encryption)\r
+\r
+(defun anarcat/message-set-encryption (&optional force)\r
+  "Automatically set the encryption depending on the recipients.\r
+\r
+If ran interactively, will overwrite settings, otherwise it will\r
+not touch existing settings, so that this can safely be ran in\r
+`message-send-hook'."\r
+  (interactive "p")\r
+  (message-goto-body)\r
+  ;; clear existing settings\r
+  (if (and force (re-search-forward "<#secure [^>]*>\n" nil t))\r
+      (replace-match "" nil nil))\r
+  ;; If we can encrypt, do so, else just sign.\r
+  (if (or force (not (re-search-forward "<#secure [^>]*>\n" nil t)))\r
+      (if (anarcat/message-guess-encryption)\r
+          (insert "<#secure method=3Dpgpmime mode=3Dsignencrypt>\n")\r
+        (insert "<#secure method=3Dpgpmime mode=3Dsign>\n"))\r
+    )\r
+)\r
+\r
+;; http://notmuchmail.org/pipermail/notmuch/2012/007340.html\r
+(defun anarcat/message-guess-encryption ()\r
+  "Return `t' if we have gpg public keys for all recipients of this message=\r
+."\r
+  (require 'epa-mail)\r
+  (if (and (not (message-news-p))  ; No encryption for news,=20\r
+           (or (message-fetch-field "to") (message-fetch-field "cc"))) ; we=\r
+ have to have one address at least\r
+      (catch :exit\r
+        (mapc\r
+         (lambda (addr)\r
+           ;; check for a usable key - taken from epa-mail.el\r
+           (if (not (epa-mail--find-usable-key\r
+                     (epg-list-keys\r
+                      (epg-make-context epa-protocol)\r
+                      (downcase (mail-strip-quoted-names addr)))\r
+                     'encrypt))\r
+               (throw :exit nil)))\r
+         (message-tokenize-header (concat\r
+                                   (message-fetch-field "to")\r
+                                   ","\r
+                                   (message-fetch-field "cc"))))\r
+        t)\r
+    nil))\r
+\r
+--=-=-=\r
+Content-Transfer-Encoding: quoted-printable\r
+\r
+\r
+Opportunistic encryption, here we go.\r
+\r
+a.\r
+\r
+=2D-=20\r
+Evil exists to glorify the good. Evil is negative good.\r
+It is a relative term. Evil can be transmuted into good.\r
+What is evil to one at one time,\r
+becomes good at another time to somebody else.\r
+                        - Sivananda\r
+\r
+--=-=-=--\r
+\r
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