verify signed content in smime encrypted and signed message

* lisp/gnus/gnus-art.el (gnus-mime-display-part): Parse pkcs7
parts (bug#40397).
(gnus-mime-security-verify-or-decrypt):
(gnus-insert-mime-security-button): Handle these parts.

* lisp/gnus/mm-decode.el (mm-verify-function-alist): Add pkcs7
functions.
(mm-decrypt-function-alist): Handle them.
(mm-possibly-verify-or-decrypt): Ditto.

* lisp/gnus/mm-view.el (mm-view-pkcs7-decrypt): Handle pkcs7.

Changes:
- structure the result of mm-dissect-buffer of application/pkcs7-mime
  like a multipart mail so there is no loosing of information of
  verification and decryption results which can now be displayed by
  gnus-mime-display-security

- adjust gnus-mime-display-part to handle application/pkcs7-mime like
  multipart/encrypted or multipart/signed

- add dummy entries to mm-verify-function-alist and
  mm-decrypt-function-alist so gnus-mime-display-security correctly
  displays "S/MIME" and not "unknown protocol"

- don't just check for multipart/signed in
  gnus-insert-mime-security-button but also for the pkcs7-mime mimetypes
  to print "Encrypted" or "Signed" accordingly in the security button

- adjust mm-possibly-verify-or-decrypt to check for smime-type to ask
  wether to verify or decrypt the part and not to always ask to decrypt

- adjust mm-view-pkcs7-decrypt and verify to call mm-sec-status so
  success information can be displayed by gnus-mime-display-security

- adjust gnus-mime-security-verify-or-decrypt to handle pkcs7-mime
  right with the done changes

1 files changed, 7 insertions, 6 deletions

diff --git a/lisp/gnus/mm-view.el b/lisp/gnus/mm-view.el
index d2a6d2cf5d3..319bc745ff8 100644
--- a/lisp/gnus/mm-view.el
+++ b/lisp/gnus/mm-view.el
@@ -634,12 +634,9 @@ If MODE is not set, try to find mode automatically."
 		 (context (epg-make-context 'CMS)))
 	     (prog1
 		 (epg-verify-string context part)
-	       (let ((result (car (epg-context-result-for context 'verify))))
+	       (let ((result (epg-context-result-for context 'verify)))
 		 (mm-sec-status
-		  'gnus-info (epg-signature-status result)
-		  'gnus-details
-		  (format "%s:%s" (epg-signature-validity result)
-			  (epg-signature-key-id result))))))))
+		  'gnus-info (epg-verify-result-to-string result)))))))
       (with-temp-buffer
 	(insert "MIME-Version: 1.0\n")
 	(mm-insert-headers "application/pkcs7-mime" "base64" "smime.p7m")
@@ -659,7 +656,11 @@ If MODE is not set, try to find mode automatically."
       ;; Use EPG/gpgsm
       (let ((part (base64-decode-string (buffer-string))))
 	(erase-buffer)
-	(insert (epg-decrypt-string (epg-make-context 'CMS) part)))
+	(insert
+         (let ((context (epg-make-context 'CMS)))
+           (prog1
+               (epg-decrypt-string context part)
+             (mm-sec-status 'gnus-info "OK")))))
     ;; Use openssl
     (insert "MIME-Version: 1.0\n")
     (mm-insert-headers "application/pkcs7-mime" "base64" "smime.p7m")