Re: new file mode: automatic gpg encryption

[mah@everybody.org (Mark A. Hershberger)]

Stefan Monnier <monnier@iro.umontreal.ca> writes:

>> On emacswiki.org, I found a snippet of code that uses mailcrypt to
>> automatically encrypt and decrypt a file with the .gpg extension.
>
>> I rewrote this to use the functions bundled with emacs and think it
>> would be a useful addition to emacs.

> How 'bout posting a patch here?

I'm pretty sure the design is wrong.  That is, you can see the buffer
fill with encrypted text for just a bit (when the before-save-hook is
run) and then return to its previous state (when after-save-hook is
run).

Since this is the first time I've worked with a mode like this at all, I
can modify it as needed.

After looking at "(elisp) Saving Buffers", I suspect that the proper
place for this is the write-file-functions hook (which
allout-write-file-hook-handler uses to encrypt specific regions of
text).

Also, I've used pgg-gpg-* functions when I should probably use pgg-*
functions.

In any case, here is the code snippet I'm using.

(defvar pgg-gpg-user-id "YOUR-ID-HERE")
(autoload 'pgg-make-temp-file "pgg" "PGG")
(autoload 'pgg-gpg-decrypt-region "pgg-gpg" "PGG GnuPG")
(define-generic-mode 'gpg-file-mode
  (list ?#) 
  nil nil
  '(".gpg\\'" ".gpg-encrypted\\'")
  (list (lambda ()
	    (add-hook 'before-save-hook
                      (lambda () 
                        (let ((pgg-output-buffer (current-buffer)))
                          (pgg-gpg-encrypt-region (point-min) (point-max)
                                                  (list pgg-gpg-user-id))))
                      nil t)
	    (add-hook 'after-save-hook 
		      (lambda ()
                        (let ((pgg-output-buffer (current-buffer)))
                          (pgg-gpg-decrypt-region (point-min) (point-max)))
			(set-buffer-modified-p nil)
			(auto-save-mode nil))
		      nil t)
            (let ((pgg-output-buffer (current-buffer)))
              (pgg-gpg-decrypt-region (point-min) (point-max)))
	    (auto-save-mode nil)
	    (set-buffer-modified-p nil)))
  "Mode for gpg encrypted files")

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