GnuPG support from inside emacs?

[Rajesh Vaidheeswarran]

Folks,

I use emacs as my mailer, and frequently use GPG to sign my mails. So,
I took a stab at a gpg-sign defun for emacs. This is decidedly not the
coolest way of doing it.. but as I started to go deep into it, I
wanted to make sure I wasn't duplicating effort.

If this seems useful, and anyone is willing to review and make
suggestions on things about either(better still, contribute), I'd be
happy to formalize it into a library with other useful stuff.

rv

(defun gpg-sign (p m)
  "gpg signs a given region"
  (interactive "r")
  (let ((passstr "Enter passphrase: ")
        (pass (read-passwd "Enter passphrase: "))
        (gpg-buf (get-buffer-create "**gpg-sign**"))
        (gpg-prog "gpg")
        (proc ""))
    ;; create a gpg signing buffer and clear it up.
    (save-excursion
      (set-buffer gpg-buf)
      (display-buffer gpg-buf t t)
      (goto-char (point-min))
      (kill-region (point-min) (point-max))
      (insert "gpg process: " proc "\n"))

    ;; start the process
    (setq proc (start-process "gpg" gpg-buf gpg-prog "--clearsign"))

    ;; make sure that it has asked for the pass phrase....
    (save-excursion
      (set-buffer gpg-buf)
      (goto-char (point-min))
      (while (equal nil (re-search-forward passstr (point-max) t))
        (message "waiting for gpg...")
        (sleep-for 0 500)))

    ;; send the passphrase..
    (process-send-string proc pass)
    (process-send-string proc "\n")
    (process-send-string proc "\n")

    ;; send a newline to the buffer (not the process) for clarity
    ;; and ease of cut and paste.
    (save-excursion
      (set-buffer gpg-buf)
      (goto-char (point-max))
      (insert "\n\n"))
    (message "inserting contents between %s and %s into %s" p m proc)

    ;; send the text to be signed...
    (save-restriction
      (narrow-to-region p m)
      (process-send-region proc (point-min) (point-max)))

    ;; and close the input stream. 
    (process-send-eof proc)
    (process-send-eof proc)

    ;; if called with prefix-arg, replace the source region with the
    ;; signed region.
    (if current-prefix-arg
        (let ((str ""))
          (save-excursion
            (set-buffer gpg-buf)
            (goto-char (point-min))
            (setq str (gpg-search-region (point-min) (point-max))))
          (save-restriction
            (narrow-to-region p m)
            ;;(goto-char (point-min))
            (goto-char (point-max))
            ;;(delete-region (point-min) (point-max))
            (insert str))))))

(defun gpg-search-region (p m)
  (interactive "r")
  (let ((str ""))
    (save-restriction
      (goto-char p)
      (set-mark m)
      (narrow-to-region p m)
      (if (search-forward "-----BEGIN PGP SIGNED MESSAGE-----")
          (save-restriction
            (narrow-to-region (match-beginning 0) (point-max))
            (goto-char (point-min))
            (if (search-forward "-----END PGP SIGNATURE-----")
                (save-restriction
                  (narrow-to-region (point-min) (match-end 0))
                  (setq str (buffer-string)))
              (message "No match for END found!")))
        (message "No match for BEGIN found!"))
      str)))