[Emacs-diffs] /srv/bzr/emacs/trunk r111432: lisp/gnus/mml-smime.el: Support signing by sender.

[Daiki Ueno]

------------------------------------------------------------
revno: 111432
committer: Daiki Ueno <address@hidden>
branch nick: trunk
timestamp: Mon 2013-01-07 12:59:02 +0900
message:
  lisp/gnus/mml-smime.el: Support signing by sender.
modified:
  lisp/gnus/ChangeLog
  lisp/gnus/mml-smime.el

=== modified file 'lisp/gnus/ChangeLog'
--- a/lisp/gnus/ChangeLog       2013-01-02 16:13:04 +0000
+++ b/lisp/gnus/ChangeLog       2013-01-07 03:59:02 +0000
@@ -1,3 +1,13 @@
+2013-01-07  Daiki Ueno  <address@hidden>
+
+       * mml-smime.el: Support signing by sender.
+       Requested by Uwe Brauer.
+       (mml-smime-sign-with-sender): New user option analogous
+       to mml2015-sign-with-sender.
+       (mml-smime-epg-sign): Respect mml-smime-sign-with-sender.
+       (mml-smime-epg-find-usable-secret-key): New helper function copied from
+       mml2015.el.
+
 2012-12-31  Lars Magne Ingebrigtsen  <address@hidden>
 
        * gnus-msg.el (gnus-inews-insert-gcc): Don't insert Gcc headers if Gnus

=== modified file 'lisp/gnus/mml-smime.el'
--- a/lisp/gnus/mml-smime.el    2013-01-01 09:11:05 +0000
+++ b/lisp/gnus/mml-smime.el    2013-01-07 03:59:02 +0000
@@ -74,6 +74,11 @@
   :group 'mime-security
   :type '(repeat (string :tag "Key ID")))
 
+(defcustom mml-smime-sign-with-sender nil
+  "If t, use message sender so find a key to sign with."
+  :group 'mime-security
+  :type 'boolean)
+
 (defun mml-smime-sign (cont)
   (let ((func (nth 1 (assq mml-smime-use mml-smime-function-alist))))
     (if func
@@ -366,6 +371,24 @@
          (setq pointer (cdr pointer))))
       (setq keys (cdr keys)))))
 
+;; XXX: since gpg --list-secret-keys does not return validity of each
+;; key, `mml-smime-epg-find-usable-key' defined above is not enough for
+;; secret keys.  The function `mml-smime-epg-find-usable-secret-key'
+;; below looks at appropriate public keys to check usability.
+(defun mml-smime-epg-find-usable-secret-key (context name usage)
+  (let ((secret-keys (epg-list-keys context name t))
+       secret-key)
+    (while (and (not secret-key) secret-keys)
+      (if (mml-smime-epg-find-usable-key
+          (epg-list-keys context (epg-sub-key-fingerprint
+                                  (car (epg-key-sub-key-list
+                                        (car secret-keys)))))
+          usage)
+         (setq secret-key (car secret-keys)
+               secret-keys nil)
+       (setq secret-keys (cdr secret-keys))))
+    secret-key))
+
 (autoload 'mml-compute-boundary "mml")
 
 ;; We require mm-decode, which requires mm-bodies, which autoloads
@@ -376,29 +399,36 @@
   (let* ((inhibit-redisplay t)
         (context (epg-make-context 'CMS))
         (boundary (mml-compute-boundary cont))
+        (sender (message-options-get 'message-sender))
+        (signer-names (or mml-smime-signers
+                          (if (and mml-smime-sign-with-sender sender)
+                              (list (concat "<" sender ">")))))
         signer-key
         (signers
          (or (message-options-get 'mml-smime-epg-signers)
              (message-options-set
-             'mml-smime-epg-signers
-             (if (eq mm-sign-option 'guided)
-                 (epa-select-keys context "\
+              'mml-smime-epg-signers
+              (if (eq mm-sign-option 'guided)
+                  (epa-select-keys context "\
 Select keys for signing.
 If no one is selected, default secret key is used.  "
-                                  mml-smime-signers t)
-               (if mml-smime-signers
-                   (mapcar
-                    (lambda (signer)
-                      (setq signer-key (mml-smime-epg-find-usable-key
-                                        (epg-list-keys context signer t)
-                                        'sign))
-                      (unless (or signer-key
-                                  (y-or-n-p
-                                   (format "No secret key for %s; skip it? "
+                                   signer-names
+                                   t)
+                (if (or sender mml-smime-signers)
+                    (delq nil
+                          (mapcar
+                           (lambda (signer)
+                             (setq signer-key
+                                   (mml-smime-epg-find-usable-secret-key
+                                    context signer 'sign))
+                             (unless (or signer-key
+                                         (y-or-n-p
+                                          (format
+                                           "No secret key for %s; skip it? "
                                            signer)))
-                        (error "No secret key for %s" signer))
-                      signer-key)
-                    mml-smime-signers))))))
+                               (error "No secret key for %s" signer))
+                             signer-key)
+                           signer-names)))))))
         signature micalg)
     (epg-context-set-signers context signers)
     (if mml-smime-cache-passphrase