1 ;;; epa-file.el --- the EasyPG Assistant, transparent file encryption
2 ;; Copyright (C) 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
4 ;; Author: Daiki Ueno <ueno@unixuser.org>
5 ;; Keywords: PGP, GnuPG
7 ;; This file is part of GNU Emacs.
9 ;; GNU Emacs is free software: you can redistribute it and/or modify
10 ;; it under the terms of the GNU General Public License as published by
11 ;; the Free Software Foundation, either version 3 of the License, or
12 ;; (at your option) any later version.
14 ;; GNU Emacs is distributed in the hope that it will be useful,
15 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
16 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 ;; GNU General Public License for more details.
19 ;; You should have received a copy of the GNU General Public License
20 ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
27 (defcustom epa-file-cache-passphrase-for-symmetric-encryption nil
28 "If non-nil, cache passphrase for symmetric encryption.
30 For security reasons, this option is turned off by default and
31 not recommended to use. Instead, consider using public-key
32 encryption with gpg-agent which does the same job in a safer
37 (defcustom epa-file-select-keys nil
38 "If non-nil, always asks user to select recipients."
42 (defvar epa-file-passphrase-alist nil)
45 (if (fboundp 'encode-coding-string)
46 (defalias 'epa-file--encode-coding-string 'encode-coding-string)
47 (defalias 'epa-file--encode-coding-string 'identity)))
50 (if (fboundp 'decode-coding-string)
51 (defalias 'epa-file--decode-coding-string 'decode-coding-string)
52 (defalias 'epa-file--decode-coding-string 'identity)))
54 (defun epa-file-passphrase-callback-function (context key-id file)
55 (if (and epa-file-cache-passphrase-for-symmetric-encryption
58 (setq file (file-truename file))
59 (let ((entry (assoc file epa-file-passphrase-alist))
61 (or (copy-sequence (cdr entry))
64 (setq entry (list file)
65 epa-file-passphrase-alist
67 epa-file-passphrase-alist)))
68 (setq passphrase (epa-passphrase-callback-function context
70 (setcdr entry (copy-sequence passphrase))
72 (epa-passphrase-callback-function context key-id nil)))
75 (defun epa-file-handler (operation &rest args)
77 (let ((op (get operation 'epa-file)))
80 (epa-file-run-real-handler operation args)))))
82 (defun epa-file-run-real-handler (operation args)
83 (let ((inhibit-file-name-handlers
84 (cons 'epa-file-handler
85 (and (eq inhibit-file-name-operation operation)
86 inhibit-file-name-handlers)))
87 (inhibit-file-name-operation operation))
88 (apply operation args)))
90 (defun epa-file-decode-and-insert (string file visit beg end replace)
91 (if (fboundp 'decode-coding-inserted-region)
93 (narrow-to-region (point) (point))
94 (insert (if enable-multibyte-characters
95 (string-to-multibyte string)
97 (decode-coding-inserted-region
98 (point-min) (point-max)
99 (substring file 0 (string-match epa-file-name-regexp file))
100 visit beg end replace))
101 (insert (epa-file--decode-coding-string string (or coding-system-for-read
104 (defvar epa-file-error nil)
105 (defun epa-file--find-file-not-found-function ()
106 (let ((error epa-file-error))
107 (save-window-excursion
110 (cons "Opening input file" (cdr error)))))
112 (defvar last-coding-system-used)
113 (defun epa-file-insert-file-contents (file &optional visit beg end replace)
114 (barf-if-buffer-read-only)
115 (if (and visit (or beg end))
116 (error "Attempt to visit less than an entire file"))
117 (setq file (expand-file-name file))
120 (epa-file-run-real-handler #'file-local-copy (list file))
122 (local-file (or local-copy file))
123 (context (epg-make-context))
126 (setq buffer-file-name file))
127 (epg-context-set-passphrase-callback
129 (cons #'epa-file-passphrase-callback-function
131 (epg-context-set-progress-callback context
132 #'epa-progress-callback-function)
136 (goto-char (point-min)))
137 (condition-case error
138 (setq string (epg-decrypt-file context local-file nil))
140 (if (setq entry (assoc file epa-file-passphrase-alist))
142 ;; Hack to prevent find-file from opening empty buffer
143 ;; when decryption failed (bug#6568). See the place
144 ;; where `find-file-not-found-functions' are called in
145 ;; `find-file-noselect-1'.
146 (when (file-exists-p local-file)
147 (make-local-variable 'epa-file-error)
148 (setq epa-file-error error)
149 (add-hook 'find-file-not-found-functions
150 'epa-file--find-file-not-found-function
153 (cons "Opening input file" (cdr error)))))
154 (make-local-variable 'epa-file-encrypt-to)
155 (setq epa-file-encrypt-to
156 (mapcar #'car (epg-context-result-for context 'encrypted-to)))
158 (setq string (substring string (or beg 0) end)))
161 (narrow-to-region (point) (point))
162 (epa-file-decode-and-insert string file visit beg end replace)
163 (setq length (- (point-max) (point-min))))
165 (delete-region (point) (point-max)))
167 (set-visited-file-modtime))))
169 (file-exists-p local-copy))
170 (delete-file local-copy)))
172 (put 'insert-file-contents 'epa-file 'epa-file-insert-file-contents)
174 (defun epa-file-write-region (start end file &optional append visit lockname
177 (error "Can't append to the file"))
178 (setq file (expand-file-name file))
179 (let* ((coding-system (or coding-system-for-write
180 (if (fboundp 'select-safe-coding-system)
181 ;; This is needed since Emacs 22 has
182 ;; no-conversion setting for *.gpg in
183 ;; `auto-coding-alist'.
184 (let ((buffer-file-name
185 (file-name-sans-extension file)))
186 (select-safe-coding-system
187 (point-min) (point-max)))
188 buffer-file-coding-system)))
189 (context (epg-make-context))
190 (coding-system-for-write 'binary)
194 ((listp epa-file-encrypt-to) epa-file-encrypt-to)
195 ((stringp epa-file-encrypt-to) (list epa-file-encrypt-to)))))
196 (epg-context-set-passphrase-callback
198 (cons #'epa-file-passphrase-callback-function
200 (epg-context-set-progress-callback context
201 #'epa-progress-callback-function)
202 (epg-context-set-armor context epa-armor)
203 (condition-case error
208 (epa-file--encode-coding-string start coding-system)
210 (setq start (point-min)
212 (epa-file--encode-coding-string (buffer-substring start end)
214 (if (or epa-file-select-keys
215 (not (local-variable-p 'epa-file-encrypt-to
219 "Select recipents for encryption.
220 If no one is selected, symmetric encryption will be performed. "
222 (if epa-file-encrypt-to
223 (epg-list-keys context recipients)))))
225 (if (setq entry (assoc file epa-file-passphrase-alist))
227 (signal 'file-error (cons "Opening output file" (cdr error)))))
228 (epa-file-run-real-handler
230 (list string nil file append visit lockname mustbenew))
231 (if (boundp 'last-coding-system-used)
232 (setq last-coding-system-used coding-system))
235 (setq buffer-file-name file)
236 (set-visited-file-modtime))
239 (set-visited-file-modtime)
240 (setq buffer-file-name visit))))
244 (message "Wrote %s" buffer-file-name))))
245 (put 'write-region 'epa-file 'epa-file-write-region)
247 (defun epa-file-select-keys ()
248 "Select recipients for encryption."
250 (make-local-variable 'epa-file-encrypt-to)
251 (setq epa-file-encrypt-to
254 (epg-sub-key-id (car (epg-key-sub-key-list key))))
257 "Select recipents for encryption.
258 If no one is selected, symmetric encryption will be performed. "))))
261 (defun epa-file-enable ()
263 (if (memq epa-file-handler file-name-handler-alist)
264 (message "`epa-file' already enabled")
265 (setq file-name-handler-alist
266 (cons epa-file-handler file-name-handler-alist))
267 (add-hook 'find-file-hook 'epa-file-find-file-hook)
268 (setq auto-mode-alist (cons epa-file-auto-mode-alist-entry auto-mode-alist))
269 (message "`epa-file' enabled")))
272 (defun epa-file-disable ()
274 (if (memq epa-file-handler file-name-handler-alist)
276 (setq file-name-handler-alist
277 (delq epa-file-handler file-name-handler-alist))
278 (remove-hook 'find-file-hook 'epa-file-find-file-hook)
279 (setq auto-mode-alist (delq epa-file-auto-mode-alist-entry
281 (message "`epa-file' disabled"))
282 (message "`epa-file' already disabled")))
286 ;; arch-tag: 5715152f-0eb1-4dbc-9008-07098775314d
287 ;;; epa-file.el ends here