;;; org-crypt.el --- Public Key Encryption for Org Entries -*- lexical-binding: t; -*-
|
;; Copyright (C) 2007-2018 Free Software Foundation, Inc.
|
|
;; Emacs Lisp Archive Entry
|
;; Filename: org-crypt.el
|
;; Keywords: org-mode
|
;; Author: John Wiegley <johnw@gnu.org>
|
;; Maintainer: Peter Jones <pjones@pmade.com>
|
;; Description: Adds public key encryption to Org buffers
|
;; URL: http://www.newartisans.com/software/emacs.html
|
;; Compatibility: Emacs22
|
|
;; This file is part of GNU Emacs.
|
;;
|
;; GNU Emacs is free software: you can redistribute it and/or modify
|
;; it under the terms of the GNU General Public License as published by
|
;; the Free Software Foundation, either version 3 of the License, or
|
;; (at your option) any later version.
|
|
;; GNU Emacs is distributed in the hope that it will be useful,
|
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
|
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
;; GNU General Public License for more details.
|
|
;; You should have received a copy of the GNU General Public License
|
;; along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>.
|
|
;;; Commentary:
|
|
;; Right now this is just a set of functions to play with. It depends
|
;; on the epg library. Here's how you would use it:
|
;;
|
;; 1. To mark an entry for encryption, tag the heading with "crypt".
|
;; You can change the tag to any complex tag matching string by
|
;; setting the `org-crypt-tag-matcher' variable.
|
;;
|
;; 2. Set the encryption key to use in the `org-crypt-key' variable,
|
;; or use `M-x org-set-property' to set the property CRYPTKEY to
|
;; any address in your public keyring. The text of the entry (but
|
;; not its properties or headline) will be encrypted for this user.
|
;; For them to read it, the corresponding secret key must be
|
;; located in the secret key ring of the account where you try to
|
;; decrypt it. This makes it possible to leave secure notes that
|
;; only the intended recipient can read in a shared-org-mode-files
|
;; scenario.
|
;; If the key is not set, org-crypt will default to symmetric encryption.
|
;;
|
;; 3. To later decrypt an entry, use `org-decrypt-entries' or
|
;; `org-decrypt-entry'. It might be useful to bind this to a key,
|
;; like C-c C-/. I hope that in the future, C-c C-r can be might
|
;; overloaded to also decrypt an entry if it's encrypted, since
|
;; that fits nicely with the meaning of "reveal".
|
;;
|
;; 4. To automatically encrypt all necessary entries when saving a
|
;; file, call `org-crypt-use-before-save-magic' after loading
|
;; org-crypt.el.
|
|
;;; Thanks:
|
|
;; - Carsten Dominik
|
;; - Vitaly Ostanin
|
|
(require 'org)
|
|
;;; Code:
|
|
(declare-function epg-decrypt-string "epg" (context cipher))
|
(declare-function epg-list-keys "epg" (context &optional name mode))
|
(declare-function epg-make-context "epg"
|
(&optional protocol armor textmode include-certs
|
cipher-algorithm digest-algorithm
|
compress-algorithm))
|
(declare-function epg-encrypt-string "epg"
|
(context plain recipients &optional sign always-trust))
|
(defvar epg-context)
|
|
|
(defgroup org-crypt nil
|
"Org Crypt."
|
:tag "Org Crypt"
|
:group 'org)
|
|
(defcustom org-crypt-tag-matcher "crypt"
|
"The tag matcher used to find headings whose contents should be encrypted.
|
|
See the \"Match syntax\" section of the org manual for more details."
|
:type 'string
|
:group 'org-crypt)
|
|
(defcustom org-crypt-key ""
|
"The default key to use when encrypting the contents of a heading.
|
|
This setting can also be overridden in the CRYPTKEY property."
|
:type 'string
|
:group 'org-crypt)
|
|
(defcustom org-crypt-disable-auto-save 'ask
|
"What org-decrypt should do if `auto-save-mode' is enabled.
|
|
t : Disable auto-save-mode for the current buffer
|
prior to decrypting an entry.
|
|
nil : Leave auto-save-mode enabled.
|
This may cause data to be written to disk unencrypted!
|
|
`ask' : Ask user whether or not to disable auto-save-mode
|
for the current buffer.
|
|
`encrypt': Leave auto-save-mode enabled for the current buffer,
|
but automatically re-encrypt all decrypted entries
|
*before* auto-saving.
|
NOTE: This only works for entries which have a tag
|
that matches `org-crypt-tag-matcher'."
|
:group 'org-crypt
|
:version "24.1"
|
:type '(choice (const :tag "Always" t)
|
(const :tag "Never" nil)
|
(const :tag "Ask" ask)
|
(const :tag "Encrypt" encrypt)))
|
|
(defun org-crypt-check-auto-save ()
|
"Check whether auto-save-mode is enabled for the current buffer.
|
|
`auto-save-mode' may cause leakage when decrypting entries, so
|
check whether it's enabled, and decide what to do about it.
|
|
See `org-crypt-disable-auto-save'."
|
(when buffer-auto-save-file-name
|
(cond
|
((or
|
(eq org-crypt-disable-auto-save t)
|
(and
|
(eq org-crypt-disable-auto-save 'ask)
|
(y-or-n-p "org-decrypt: auto-save-mode may cause leakage. Disable it for current buffer? ")))
|
(message "org-decrypt: Disabling auto-save-mode for %s"
|
(or (buffer-file-name) (current-buffer)))
|
;; The argument to auto-save-mode has to be "-1", since
|
;; giving a "nil" argument toggles instead of disabling.
|
(auto-save-mode -1))
|
((eq org-crypt-disable-auto-save nil)
|
(message "org-decrypt: Decrypting entry with auto-save-mode enabled. This may cause leakage."))
|
((eq org-crypt-disable-auto-save 'encrypt)
|
(message "org-decrypt: Enabling re-encryption on auto-save.")
|
(add-hook 'auto-save-hook
|
(lambda ()
|
(message "org-crypt: Re-encrypting all decrypted entries due to auto-save.")
|
(org-encrypt-entries))
|
nil t))
|
(t nil))))
|
|
(defun org-crypt-key-for-heading ()
|
"Return the encryption key for the current heading."
|
(save-excursion
|
(org-back-to-heading t)
|
(or (org-entry-get nil "CRYPTKEY" 'selective)
|
org-crypt-key
|
(and (boundp 'epa-file-encrypt-to) epa-file-encrypt-to)
|
(message "No crypt key set, using symmetric encryption."))))
|
|
(defun org-encrypt-string (str crypt-key)
|
"Return STR encrypted with CRYPT-KEY."
|
;; Text and key have to be identical, otherwise we re-crypt.
|
(if (and (string= crypt-key (get-text-property 0 'org-crypt-key str))
|
(string= (sha1 str) (get-text-property 0 'org-crypt-checksum str)))
|
(get-text-property 0 'org-crypt-text str)
|
(setq-local epg-context (epg-make-context nil t t))
|
(epg-encrypt-string epg-context str (epg-list-keys epg-context crypt-key))))
|
|
(defun org-encrypt-entry ()
|
"Encrypt the content of the current headline."
|
(interactive)
|
(require 'epg)
|
(org-with-wide-buffer
|
(org-back-to-heading t)
|
(setq-local epg-context (epg-make-context nil t t))
|
(let ((start-heading (point)))
|
(org-end-of-meta-data)
|
(unless (looking-at-p "-----BEGIN PGP MESSAGE-----")
|
(let ((folded (org-invisible-p))
|
(crypt-key (org-crypt-key-for-heading))
|
(beg (point)))
|
(goto-char start-heading)
|
(org-end-of-subtree t t)
|
(org-back-over-empty-lines)
|
(let ((contents (delete-and-extract-region beg (point))))
|
(condition-case err
|
(insert (org-encrypt-string contents crypt-key))
|
;; If encryption failed, make sure to insert back entry
|
;; contents in the buffer.
|
(error (insert contents) (error (nth 1 err)))))
|
(when folded
|
(goto-char start-heading)
|
(outline-hide-subtree))
|
nil)))))
|
|
(defun org-decrypt-entry ()
|
"Decrypt the content of the current headline."
|
(interactive)
|
(require 'epg)
|
(unless (org-before-first-heading-p)
|
(org-with-wide-buffer
|
(org-back-to-heading t)
|
(let ((heading-point (point))
|
(heading-was-invisible-p
|
(save-excursion
|
(outline-end-of-heading)
|
(org-invisible-p))))
|
(org-end-of-meta-data)
|
(when (looking-at "-----BEGIN PGP MESSAGE-----")
|
(org-crypt-check-auto-save)
|
(setq-local epg-context (epg-make-context nil t t))
|
(let* ((end (save-excursion
|
(search-forward "-----END PGP MESSAGE-----")
|
(forward-line)
|
(point)))
|
(encrypted-text (buffer-substring-no-properties (point) end))
|
(decrypted-text
|
(decode-coding-string
|
(epg-decrypt-string
|
epg-context
|
encrypted-text)
|
'utf-8)))
|
;; Delete region starting just before point, because the
|
;; outline property starts at the \n of the heading.
|
(delete-region (1- (point)) end)
|
;; Store a checksum of the decrypted and the encrypted
|
;; text value. This allows reusing the same encrypted text
|
;; if the text does not change, and therefore avoid a
|
;; re-encryption process.
|
(insert "\n" (propertize decrypted-text
|
'org-crypt-checksum (sha1 decrypted-text)
|
'org-crypt-key (org-crypt-key-for-heading)
|
'org-crypt-text encrypted-text))
|
(when heading-was-invisible-p
|
(goto-char heading-point)
|
(org-flag-subtree t))
|
nil))))))
|
|
(defun org-encrypt-entries ()
|
"Encrypt all top-level entries in the current buffer."
|
(interactive)
|
(let ((org--matcher-tags-todo-only nil))
|
(org-scan-tags
|
'org-encrypt-entry
|
(cdr (org-make-tags-matcher org-crypt-tag-matcher))
|
org--matcher-tags-todo-only)))
|
|
(defun org-decrypt-entries ()
|
"Decrypt all entries in the current buffer."
|
(interactive)
|
(let ((org--matcher-tags-todo-only nil))
|
(org-scan-tags
|
'org-decrypt-entry
|
(cdr (org-make-tags-matcher org-crypt-tag-matcher))
|
org--matcher-tags-todo-only)))
|
|
(defun org-at-encrypted-entry-p ()
|
"Is the current entry encrypted?"
|
(unless (org-before-first-heading-p)
|
(save-excursion
|
(org-back-to-heading t)
|
(search-forward "-----BEGIN PGP MESSAGE-----"
|
(save-excursion (outline-next-heading)) t))))
|
|
(defun org-crypt-use-before-save-magic ()
|
"Add a hook to automatically encrypt entries before a file is saved to disk."
|
(add-hook
|
'org-mode-hook
|
(lambda () (add-hook 'before-save-hook 'org-encrypt-entries nil t))))
|
|
(add-hook 'org-reveal-start-hook 'org-decrypt-entry)
|
|
(provide 'org-crypt)
|
|
;;; org-crypt.el ends here
|
