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
8 ;; This file is part of GNU Emacs.
10 ;; GNU Emacs is free software: you can redistribute it and/or modify
11 ;; it under the terms of the GNU General Public License as published by
12 ;; the Free Software Foundation, either version 3 of the License, or
13 ;; (at your option) any later version.
15 ;; GNU Emacs is distributed in the hope that it will be useful,
16 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 ;; GNU General Public License for more details.
20 ;; You should have received a copy of the GNU General Public License
21 ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
28 (defcustom epa-file-cache-passphrase-for-symmetric-encryption nil
29 "If non-nil, cache passphrase for symmetric encryption.
31 For security reasons, this option is turned off by default and
32 not recommended to use. Instead, consider using public-key
33 encryption with gpg-agent which does the same job in a safer
38 (defcustom epa-file-select-keys nil
39 "If non-nil, always asks user to select recipients."
43 (defvar epa-file-passphrase-alist nil)
46 (if (fboundp 'encode-coding-string)
47 (defalias 'epa-file--encode-coding-string 'encode-coding-string)
48 (defalias 'epa-file--encode-coding-string 'identity)))
51 (if (fboundp 'decode-coding-string)
52 (defalias 'epa-file--decode-coding-string 'decode-coding-string)
53 (defalias 'epa-file--decode-coding-string 'identity)))
55 (defun epa-file-passphrase-callback-function (context key-id file)
56 (if (and epa-file-cache-passphrase-for-symmetric-encryption
59 (setq file (file-truename file))
60 (let ((entry (assoc file epa-file-passphrase-alist))
62 (or (copy-sequence (cdr entry))
65 (setq entry (list file)
66 epa-file-passphrase-alist
68 epa-file-passphrase-alist)))
69 (setq passphrase (epa-passphrase-callback-function context
72 (setcdr entry (copy-sequence passphrase))
74 (epa-passphrase-callback-function context key-id file)))
77 (defun epa-file-handler (operation &rest args)
79 (let ((op (get operation 'epa-file)))
82 (epa-file-run-real-handler operation args)))))
84 (defun epa-file-run-real-handler (operation args)
85 (let ((inhibit-file-name-handlers
86 (cons 'epa-file-handler
87 (and (eq inhibit-file-name-operation operation)
88 inhibit-file-name-handlers)))
89 (inhibit-file-name-operation operation))
90 (apply operation args)))
92 (defun epa-file-decode-and-insert (string file visit beg end replace)
93 (if (fboundp 'decode-coding-inserted-region)
95 (narrow-to-region (point) (point))
96 (insert (if enable-multibyte-characters
97 (string-to-multibyte string)
99 (decode-coding-inserted-region
100 (point-min) (point-max)
101 (substring file 0 (string-match epa-file-name-regexp file))
102 visit beg end replace))
103 (insert (epa-file--decode-coding-string string (or coding-system-for-read
106 (defvar epa-file-error nil)
107 (defun epa-file--find-file-not-found-function ()
108 (let ((error epa-file-error))
109 (save-window-excursion
112 (cons "Opening input file" (cdr error)))))
114 (defvar last-coding-system-used)
115 (defun epa-file-insert-file-contents (file &optional visit beg end replace)
116 (barf-if-buffer-read-only)
117 (if (and visit (or beg end))
118 (error "Attempt to visit less than an entire file"))
119 (setq file (expand-file-name file))
122 (epa-file-run-real-handler #'file-local-copy (list file))
124 (local-file (or local-copy file))
125 (context (epg-make-context))
128 (setq buffer-file-name file))
129 (epg-context-set-passphrase-callback
131 (cons #'epa-file-passphrase-callback-function
133 (epg-context-set-progress-callback context
134 #'epa-progress-callback-function)
138 (goto-char (point-min)))
139 (condition-case error
140 (setq string (epg-decrypt-file context local-file nil))
142 (if (setq entry (assoc file epa-file-passphrase-alist))
144 ;; Hack to prevent find-file from opening empty buffer
145 ;; when decryption failed (bug#6568). See the place
146 ;; where `find-file-not-found-functions' are called in
147 ;; `find-file-noselect-1'.
148 (when (file-exists-p local-file)
149 (make-local-variable 'epa-file-error)
150 (setq epa-file-error error)
151 (add-hook 'find-file-not-found-functions
152 'epa-file--find-file-not-found-function
155 (cons "Opening input file" (cdr error)))))
156 (make-local-variable 'epa-file-encrypt-to)
157 (setq epa-file-encrypt-to
158 (mapcar #'car (epg-context-result-for context 'encrypted-to)))
160 (setq string (substring string (or beg 0) end)))
162 ;; If visiting, bind off buffer-file-name so that
163 ;; file-locking will not ask whether we should
164 ;; really edit the buffer.
165 (let ((buffer-file-name
166 (if visit nil buffer-file-name)))
168 (narrow-to-region (point) (point))
169 (epa-file-decode-and-insert string file visit beg end replace)
170 (setq length (- (point-max) (point-min))))
172 (delete-region (point) (point-max))))
174 (set-visited-file-modtime))))
176 (file-exists-p local-copy))
177 (delete-file local-copy)))
179 (put 'insert-file-contents 'epa-file 'epa-file-insert-file-contents)
181 (defun epa-file-write-region (start end file &optional append visit lockname
184 (error "Can't append to the file"))
185 (setq file (expand-file-name file))
186 (let* ((coding-system (or coding-system-for-write
187 (if (fboundp 'select-safe-coding-system)
188 ;; This is needed since Emacs 22 has
189 ;; no-conversion setting for *.gpg in
190 ;; `auto-coding-alist'.
191 (let ((buffer-file-name
192 (file-name-sans-extension file)))
193 (select-safe-coding-system
194 (point-min) (point-max)))
195 buffer-file-coding-system)))
196 (context (epg-make-context))
197 (coding-system-for-write 'binary)
201 ((listp epa-file-encrypt-to) epa-file-encrypt-to)
202 ((stringp epa-file-encrypt-to) (list epa-file-encrypt-to)))))
203 (epg-context-set-passphrase-callback
205 (cons #'epa-file-passphrase-callback-function
207 (epg-context-set-progress-callback context
208 #'epa-progress-callback-function)
209 (epg-context-set-armor context epa-armor)
210 (condition-case error
215 (epa-file--encode-coding-string start coding-system)
217 (setq start (point-min)
219 (epa-file--encode-coding-string (buffer-substring start end)
221 (if (or epa-file-select-keys
222 (not (local-variable-p 'epa-file-encrypt-to
226 "Select recipents for encryption.
227 If no one is selected, symmetric encryption will be performed. "
229 (if epa-file-encrypt-to
230 (epg-list-keys context recipients)))))
232 (if (setq entry (assoc file epa-file-passphrase-alist))
234 (signal 'file-error (cons "Opening output file" (cdr error)))))
235 (epa-file-run-real-handler
237 (list string nil file append visit lockname mustbenew))
238 (if (boundp 'last-coding-system-used)
239 (setq last-coding-system-used coding-system))
242 (setq buffer-file-name file)
243 (set-visited-file-modtime))
246 (set-visited-file-modtime)
247 (setq buffer-file-name visit))))
251 (message "Wrote %s" buffer-file-name))))
252 (put 'write-region 'epa-file 'epa-file-write-region)
254 (defun epa-file-select-keys ()
255 "Select recipients for encryption."
257 (make-local-variable 'epa-file-encrypt-to)
258 (setq epa-file-encrypt-to
261 (epg-sub-key-id (car (epg-key-sub-key-list key))))
264 "Select recipents for encryption.
265 If no one is selected, symmetric encryption will be performed. "))))
268 (defun epa-file-enable ()
270 (if (memq epa-file-handler file-name-handler-alist)
271 (message "`epa-file' already enabled")
272 (setq file-name-handler-alist
273 (cons epa-file-handler file-name-handler-alist))
274 (add-hook 'find-file-hook 'epa-file-find-file-hook)
275 (setq auto-mode-alist (cons epa-file-auto-mode-alist-entry auto-mode-alist))
276 (message "`epa-file' enabled")))
279 (defun epa-file-disable ()
281 (if (memq epa-file-handler file-name-handler-alist)
283 (setq file-name-handler-alist
284 (delq epa-file-handler file-name-handler-alist))
285 (remove-hook 'find-file-hook 'epa-file-find-file-hook)
286 (setq auto-mode-alist (delq epa-file-auto-mode-alist-entry
288 (message "`epa-file' disabled"))
289 (message "`epa-file' already disabled")))
293 ;; arch-tag: 5715152f-0eb1-4dbc-9008-07098775314d
294 ;;; epa-file.el ends here