Emacs symmetric crypto on region

;; Easiest symmetric crypto for region of text.
;;
;; Mark start of region, move cursor to end of region, then
;; hit either M-f11 to encrypt, or M-f12 to decrypt.
;; Try alternating between both (without moving cursor) to
;; see the text morph from cleartext to encrypted text back
;; and forth.
;; After encrypting you can copy or kill without moving cursor.
;; Or after pasting encrypted into buffer, hit M-f12 to decrypt
;; since pasted region is already marked.  Short, simple, easy.

;; Needed for below functions
(require 'epg)

;; Encrypt region with default password
(defun symmetric-encrypt-region (&optional n)
  "Encrypt region using symmetric crypto."
  (interactive "P")
  (let ((plain (delete-and-extract-region (point) (mark))))
    (insert-string (epg-encrypt-string (epg-make-context nil t) plain nil))))
(global-set-key [M-f11] 'symmetric-encrypt-region)

;; Decrypt region with default password
(defun symmetric-decrypt-region (&optional n)
  "Decrypt region using symmetric crypto."
  (interactive "P")
  (let ((cipher (delete-and-extract-region (point) (mark))))
    (insert-string (epg-decrypt-string (epg-make-context nil t) cipher))))
(global-set-key [M-f12] 'symmetric-decrypt-region)