emacs: Add support for PGP/MIME verification/decryption

A new emacs configuration variable "notmuch-crypto-process-mime"
controls the processing of PGP/MIME signatures and encrypted parts.
When this is set true, notmuch-query will use the notmuch show
--decrypt flag to decrypt encrypted messages and/or calculate the
sigstatus of signed messages.  If sigstatus is available, notmuch-show
will place a specially color-coded header at the begining of the
signed message.

Also included is the ability to switch decryption/verification on/off
on the fly, which is bound to M-RET in notmuch-search-mode.

1 files changed, 104 insertions, 0 deletions

diff --git a/emacs/notmuch-crypto.el b/emacs/notmuch-crypto.el
new file mode 100644
index 00000000..944452b9
--- /dev/null
+++ b/emacs/notmuch-crypto.el
@@ -0,0 +1,104 @@
+;; notmuch-crypto.el --- functions for handling display of cryptographic metadata.
+;;
+;; Copyright © Jameson Rollins
+;;
+;; This file is part of Notmuch.
+;;
+;; Notmuch is free software: you can redistribute it and/or modify it
+;; under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+;;
+;; Notmuch is distributed in the hope that it will be useful, but
+;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;; General Public License for more details.
+;;
+;; You should have received a copy of the GNU General Public License
+;; along with Notmuch.  If not, see <http://www.gnu.org/licenses/>.
+;;
+;; Authors: Jameson Rollins <jrollins@finestructure.net>
+
+(defcustom notmuch-crypto-process-mime nil
+  "Should cryptographic MIME parts be processed?
+
+If this variable is non-nil signatures in multipart/signed
+messages will be verified and multipart/encrypted parts will be
+decrypted.  The result of the crypto operation will be displayed
+in a specially colored header button at the top of the processed
+part.  Signed parts will have variously colored headers depending
+on the success or failure of the verification process and on the
+validity of user ID of the signer.
+
+The effect of setting this variable can be seen temporarily by
+viewing a signed or encrypted message with M-RET in notmuch
+search."
+  :group 'notmuch
+  :type 'boolean)
+
+(define-button-type 'notmuch-crypto-status-button-type
+  'action '(lambda (button) (message (button-get button 'help-echo)))
+  'follow-link t
+  'help-echo "Set notmuch-crypto-process-mime to process cryptographic mime parts."
+  'face '(:foreground "blue")
+  'mouse-face '(:foreground "blue"))
+
+(defun notmuch-crypto-insert-sigstatus-button (sigstatus from)
+  (let* ((status (plist-get sigstatus :status))
+	 (help-msg nil)
+	 (label "multipart/signed: signature not processed")
+	 (face '(:background "red" :foreground "black")))
+    (cond
+     ((string= status "good")
+      ; if userid present, userid has full or greater validity
+      (if (plist-member sigstatus :userid)
+	  (let ((userid (plist-get sigstatus :userid)))
+	    (setq label (concat "Good signature by: " userid))
+	    (setq face '(:background "green" :foreground "black")))
+	(let ((fingerprint (concat "0x" (plist-get sigstatus :fingerprint))))
+	  (setq label (concat "Good signature by key: " fingerprint))
+	  (setq face '(:background "orange" :foreground "black")))))
+     ((string= status "error")
+      (let ((keyid (concat "0x" (plist-get sigstatus :keyid))))
+	(setq label (concat "Unknown key ID " keyid " or unsupported algorithm"))
+	(setq face '(:background "red" :foreground "black"))))
+     ((string= status "bad")
+      (let ((keyid (concat "0x" (plist-get sigstatus :keyid))))
+	(setq label (concat "Bad signature (claimed key ID " keyid ")"))
+	(setq face '(:background "red" :foreground "black"))))
+     (t
+      (setq label "Unknown signature status")
+      (if status (setq label (concat label " \"" status "\"")))))
+    (insert-button
+     (concat "[ " label " ]")
+     :type 'notmuch-crypto-status-button-type
+     'help-echo help-msg
+     'face face
+     'mouse-face face
+     :notmuch-sigstatus sigstatus
+     :notmuch-from from)
+    (insert "\n")))
+
+(defun notmuch-crypto-insert-encstatus-button (encstatus)
+  (let* ((status (plist-get encstatus :status))
+	 (help-msg nil)
+	 (label "multipart/encrypted: decryption not attempted")
+	 (face '(:background "purple" :foreground "black")))
+    (cond
+     ((string= status "good")
+      (setq label "decryption successful"))
+     ((string= status "bad")
+      (setq label "decryption error"))
+     (t
+      (setq label (concat "unknown encstatus \"" status "\""))))
+    (insert-button
+     (concat "[ multipart/encrypted: " label " ]")
+     :type 'notmuch-crypto-status-button-type
+     'help-echo help-msg
+     'face face
+     'mouse-face face)
+    (insert "\n")))
+
+;;
+
+(provide 'notmuch-crypto)