Add support for the OpenPGP header to Emacs

* lisp/gnus/message.el (message-openpgp-header): New variable
(bug#39964).
(messasge-add-openpgp-header): New function to use it.

diff --git a/etc/NEWS b/etc/NEWS
index 5cef0eb4c870305edd0e765846e9216959834c0d..d2903449bed26fc02801021a6612bb938229e2dd 100644 (file)
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -246,6 +246,11 @@ not.
 
 ** Message
 
+*** Message now supports the OpenPGP header.
+To generate these headers, add the new function
+'messasge-add-openpgp-header' to 'message-send-hook'.  The header will
+be generated according to the new 'message-openpgp-header' variable.
+
 ---
 *** A change to how Mail-Copies-To: never is handled.
 If a user has specified Mail-Copies-To: never, and Message was asked

diff --git a/lisp/gnus/message.el b/lisp/gnus/message.el
index 819f3e41d3d5c52a979e8992bd4a121e8cd7b101..e5ddfcffffc9c805cc314ca107b983875ce8b527 100644 (file)
--- a/lisp/gnus/message.el
+++ b/lisp/gnus/message.el
@@ -2737,6 +2737,64 @@ systematically send encrypted emails when possible."
   (when (message-all-epg-keys-available-p)
     (mml-secure-message-sign-encrypt)))
 
+(defcustom message-openpgp-header nil
+  "Specification for \"OpenPGP\" header.
+
+Otherwise, the variable must be a
+list with three elements, all strings:
+- Key ID, in hexadecimal form
+- Key URL or ASCII armoured key.
+- Protection preference, one of: \"unprotected\", \"sign\",
+  \"encrypt\" or \"signencrypt\".
+
+Each value may be nil, in which case it won't be inserted. If all
+the values are nil, or `message-openpgp-header' is nil itself,
+don't insert any header."
+  :type '(choice
+         (const nil :tag "Don't add OpenPGP header")
+         (list (choice (string :tag "ID")
+                       (const nil :tag "No ID"))
+               (choice (string :tag "Key")
+                       (const nil :tag "No Key"))
+               (choice (other nil :tag "None")
+                       (const "unprotected" :tag "Unprotected")
+                       (const "sign" :tag "Sign")
+                       (const "encrypt" :tag "Encrypt")
+                       (const "signencrypt" :tag "Sign and Encrypt"))))
+  :version "28.1")
+
+(defun messasge-add-openpgp-header ()
+  "Add OpenPGP header to point to public key.
+
+Header will be constructed as specified in `message-openpgp-header'.
+
+Consider adding this function to `message-send-hook'."
+  ;; See https://tools.ietf.org/html/draft-josefsson-openpgp-mailnews-header
+  (when (and message-openpgp-header
+            (or (nth 0 message-openpgp-header)
+                (nth 1 message-openpgp-header)
+                (nth 2 message-openpgp-header)))
+    (with-temp-buffer
+      (insert "OpenPGP: ")
+      ;; add ID
+      (let (need-sep)
+       (when (nth 0 message-openpgp-header)
+         (insert "id=" (nth 0 message-openpgp-header))
+         (setq need-sep t))
+       ;; add URL
+       (when (nth 1 message-openpgp-header)
+         (when need-sep (insert "; "))
+         (if (string-match-p ";")
+             (insert "url=\"" (nth 1 message-openpgp-header) "\"")
+           (insert "url=\"" (nth 1 message-openpgp-header) "\""))
+         (setq need-sep t))
+       ;; add preference
+       (when (nth 2 message-openpgp-header)
+         (when need-sep (insert "; "))
+         (insert "preference=" (nth 2 message-openpgp-header))))
+      ;; insert header
+      (message-add-header (buffer-string)))))
+
 \f
 
 ;;;