On Sun, Oct 02, 2005 at 04:31:10PM -0400, Richard M. Stallman wrote:
>     So you would consider switching to pgg, if it would provide an
>     interface to symmetric encryption?
> 
> If someone wants to do it, and assuming the result is clean, it would 
> be a good thing to do.

Enclosed you'll find my preliminary patch to make symmetric encryption
possible with pgg.

The new function pgg-encrypt-symmetric-region asks for a passphrase
and uses it to symmetrically encrypt the given region.

Please note, this is by no means complete, just a small proof of concept.

Ken, would something along this lines be sufficient for use with allout?

cheers
sascha

cvs server: Diffing .
Index: pgg-gpg.el
===================================================================
RCS file: /cvsroot/emacs/emacs/lisp/gnus/pgg-gpg.el,v
retrieving revision 1.6
diff -u -r1.6 pgg-gpg.el
--- pgg-gpg.el	6 Aug 2005 19:51:42 -0000	1.6
+++ pgg-gpg.el	3 Oct 2005 19:13:34 -0000
@@ -4,6 +4,7 @@
 ;;   2005 Free Software Foundation, Inc.
 
 ;; Author: Daiki Ueno <ueno@unixuser.org>
+;; Symmetric encryption added by: Sascha Wilde <wilde@sha-bang.de>
 ;; Created: 1999/10/28
 ;; Keywords: PGP, OpenPGP, GnuPG
 
@@ -141,24 +142,32 @@
 
 (defun pgg-gpg-encrypt-region (start end recipients &optional sign)
   "Encrypt the current region between START and END.
+If recipients is :symmetric do symmetric encryption
 If optional argument SIGN is non-nil, do a combined sign and encrypt."
   (let* ((pgg-gpg-user-id (or pgg-gpg-user-id pgg-default-user-id))
+	 (symmetric-encryption (eq recipients :symmetric))
 	 (passphrase
-	  (when sign
-	    (pgg-read-passphrase
-	     (format "GnuPG passphrase for %s: " pgg-gpg-user-id)
-	     pgg-gpg-user-id)))
+	  (if symmetric-encryption
+	      (pgg-read-passphrase
+	       "GnuPG passphrase for symmetric encryption: ")
+	    (when sign
+	      (pgg-read-passphrase
+	       (format "GnuPG passphrase for %s: " pgg-gpg-user-id)
+	       pgg-gpg-user-id))))
 	 (args
 	  (append
-	   (list "--batch" "--armor" "--always-trust" "--encrypt")
+	   (list "--batch" "--armor" "--always-trust" 
+		 (if symmetric-encryption "--symmetric" "--encrypt"))
 	   (if sign (list "--sign" "--local-user" pgg-gpg-user-id))
-	   (if recipients
-	       (apply #'nconc
-		      (mapcar (lambda (rcpt)
-				(list pgg-gpg-recipient-argument rcpt))
-			      (append recipients
-				      (if pgg-encrypt-for-me
-					  (list pgg-gpg-user-id)))))))))
+	   (if symmetric-encryption
+	       nil
+	       (if recipients
+		   (apply #'nconc
+			  (mapcar (lambda (rcpt)
+				    (list pgg-gpg-recipient-argument rcpt))
+				  (append recipients
+					  (if pgg-encrypt-for-me
+					      (list pgg-gpg-user-id))))))))))
     (pgg-as-lbt start end 'CRLF
       (pgg-gpg-process-region start end passphrase pgg-gpg-program args))
     (when sign
Index: pgg.el
===================================================================
RCS file: /cvsroot/emacs/emacs/lisp/gnus/pgg.el,v
retrieving revision 1.8
diff -u -r1.8 pgg.el
--- pgg.el	26 Aug 2005 00:02:05 -0000	1.8
+++ pgg.el	3 Oct 2005 19:13:34 -0000
@@ -4,6 +4,7 @@
 ;;   2005 Free Software Foundation, Inc.
 
 ;; Author: Daiki Ueno <ueno@unixuser.org>
+;; Symmetric encryption added by: Sascha Wilde <wilde@sha-bang.de>
 ;; Created: 1999/10/28
 ;; Keywords: PGP
 
@@ -232,6 +233,18 @@
 	 (pgg-save-coding-system start end
 	   (pgg-invoke "encrypt-region" (or pgg-scheme pgg-default-scheme)
 		       (point-min) (point-max) rcpts sign))))
+    (when (interactive-p)
+      (pgg-display-output-buffer start end status))
+    status))
+
+;;;###autoload
+(defun pgg-encrypt-symmetric-region (start end)
+  "Encrypt the current region between START and END symmetric with passphrase."
+  (interactive "r")
+  (let ((status
+	 (pgg-save-coding-system start end
+	   (pgg-invoke "encrypt-region" (or pgg-scheme pgg-default-scheme)
+		       (point-min) (point-max) :symmetric))))
     (when (interactive-p)
       (pgg-display-output-buffer start end status))
     status))


-- 
Sascha Wilde : The most exciting phrase to hear in science, the one
             : that heralds new discoveries, is not "Eureka!" (I found
             : it!) but "That's funny ..." -- Isaac Asimov