1 ;;; epa-file.el --- the EasyPG Assistant, transparent file encryption -*- lexical-binding: t -*-
2 ;; Copyright (C) 2006-2017 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 gpg-agent which
33 does the same job in a safer way. See Info node `(epa) Caching
34 Passphrases' for more information.
36 Note that this option has no effect if you use GnuPG 2.0."
40 (defcustom epa-file-select-keys nil
41 "Control whether or not to pop up the key selection dialog.
43 If t, always asks user to select recipients.
44 If nil, query user only when `epa-file-encrypt-to' is not set.
45 If neither t nor nil, doesn't ask user. In this case, symmetric
47 :type
'(choice (const :tag
"Ask always" t
)
48 (const :tag
"Ask when recipients are not set" nil
)
49 (const :tag
"Don't ask" silent
))
52 (defvar epa-file-passphrase-alist nil
)
55 (if (fboundp 'encode-coding-string
)
56 (defalias 'epa-file--encode-coding-string
'encode-coding-string
)
57 (defalias 'epa-file--encode-coding-string
'identity
)))
60 (if (fboundp 'decode-coding-string
)
61 (defalias 'epa-file--decode-coding-string
'decode-coding-string
)
62 (defalias 'epa-file--decode-coding-string
'identity
)))
64 (defun epa-file-passphrase-callback-function (context key-id file
)
65 (if (and epa-file-cache-passphrase-for-symmetric-encryption
68 (setq file
(file-truename file
))
69 (let ((entry (assoc file epa-file-passphrase-alist
))
71 (or (copy-sequence (cdr entry
))
74 (setq entry
(list file
)
75 epa-file-passphrase-alist
77 epa-file-passphrase-alist
)))
78 (setq passphrase
(epa-passphrase-callback-function context
81 (setcdr entry
(copy-sequence passphrase
))
83 (epa-passphrase-callback-function context key-id file
)))
85 (defvar epa-inhibit nil
86 "Non-nil means don't try to decrypt .gpg files when operating on them.")
89 (defun epa-file-handler (operation &rest args
)
91 (let ((op (get operation
'epa-file
)))
92 (if (and op
(not epa-inhibit
))
94 (epa-file-run-real-handler operation args
)))))
96 (defun epa-file-run-real-handler (operation args
)
97 (let ((inhibit-file-name-handlers
98 (cons 'epa-file-handler
99 (and (eq inhibit-file-name-operation operation
)
100 inhibit-file-name-handlers
)))
101 (inhibit-file-name-operation operation
))
102 (apply operation args
)))
104 (defun epa-file-decode-and-insert (string file visit beg end replace
)
105 (if (fboundp 'decode-coding-inserted-region
)
107 (narrow-to-region (point) (point))
108 (insert (if enable-multibyte-characters
109 (string-to-multibyte string
)
111 (decode-coding-inserted-region
112 (point-min) (point-max)
113 (substring file
0 (string-match epa-file-name-regexp file
))
114 visit beg end replace
))
115 (insert (epa-file--decode-coding-string string
(or coding-system-for-read
118 (defvar epa-file-error nil
)
119 (defun epa-file--find-file-not-found-function ()
120 (let ((error epa-file-error
))
121 (save-window-excursion
123 (signal 'file-missing
124 (cons "Opening input file" (cdr error
)))))
126 (defvar last-coding-system-used
)
127 (defun epa-file-insert-file-contents (file &optional visit beg end replace
)
128 (barf-if-buffer-read-only)
129 (if (and visit
(or beg end
))
130 (error "Attempt to visit less than an entire file"))
131 (setq file
(expand-file-name file
))
134 (epa-file-run-real-handler #'file-local-copy
(list file
))
136 (local-file (or local-copy file
))
137 (context (epg-make-context))
138 (buf (current-buffer))
141 (setq buffer-file-name file
))
142 (epg-context-set-passphrase-callback
144 (cons #'epa-file-passphrase-callback-function
146 (epg-context-set-progress-callback
148 (cons #'epa-progress-callback-function
149 (format "Decrypting %s" file
)))
150 (setf (epg-context-pinentry-mode context
) epa-pinentry-mode
)
154 (goto-char (point-min)))
155 (condition-case error
156 (setq string
(epg-decrypt-file context local-file nil
))
158 (if (setq entry
(assoc file epa-file-passphrase-alist
))
160 ;; If the decryption program can't be found,
161 ;; signal that as a non-file error
162 ;; so that find-file-noselect-1 won't handle it.
163 ;; Borrowed from jka-compr.el.
164 (if (and (memq 'file-error
(get (car error
) 'error-conditions
))
165 (equal (cadr error
) "Searching for program"))
166 (error "Decryption program `%s' not found"
168 (let ((exists (file-exists-p local-file
)))
170 ;; Hack to prevent find-file from opening empty buffer
171 ;; when decryption failed (bug#6568). See the place
172 ;; where `find-file-not-found-functions' are called in
173 ;; `find-file-noselect-1'.
174 (setq-local epa-file-error error
)
175 (add-hook 'find-file-not-found-functions
176 'epa-file--find-file-not-found-function
178 (epa-display-error context
))
179 (signal (if exists
'file-error
'file-missing
)
180 (cons "Opening input file" (cdr error
))))))
181 (set-buffer buf
) ;In case timer/filter changed/killed it (bug#16029)!
182 (setq-local epa-file-encrypt-to
183 (mapcar #'car
(epg-context-result-for
184 context
'encrypted-to
)))
186 (setq string
(substring string
(or beg
0) end
)))
188 ;; If visiting, bind off buffer-file-name so that
189 ;; file-locking will not ask whether we should
190 ;; really edit the buffer.
191 (let ((buffer-file-name
192 (if visit nil buffer-file-name
)))
194 (narrow-to-region (point) (point))
195 (epa-file-decode-and-insert string file visit beg end replace
)
196 (setq length
(- (point-max) (point-min))))
198 (delete-region (point) (point-max))))
200 (set-visited-file-modtime))))
202 (file-exists-p local-copy
))
203 (delete-file local-copy
)))
205 (put 'insert-file-contents
'epa-file
'epa-file-insert-file-contents
)
207 (defun epa-file-write-region (start end file
&optional append visit lockname
210 (error "Can't append to the file"))
211 (setq file
(expand-file-name file
))
212 (let* ((coding-system (or coding-system-for-write
213 (if (fboundp 'select-safe-coding-system
)
214 ;; This is needed since Emacs 22 has
215 ;; no-conversion setting for *.gpg in
216 ;; `auto-coding-alist'.
217 (let ((buffer-file-name
218 (file-name-sans-extension file
)))
219 (select-safe-coding-system
220 (point-min) (point-max)))
221 buffer-file-coding-system
)))
222 (context (epg-make-context))
223 (coding-system-for-write 'binary
)
227 ((listp epa-file-encrypt-to
) epa-file-encrypt-to
)
228 ((stringp epa-file-encrypt-to
) (list epa-file-encrypt-to
))))
230 (epg-context-set-passphrase-callback
232 (cons #'epa-file-passphrase-callback-function
234 (epg-context-set-progress-callback
236 (cons #'epa-progress-callback-function
237 (format "Encrypting %s" file
)))
238 (setf (epg-context-armor context
) epa-armor
)
239 (setf (epg-context-pinentry-mode context
) epa-pinentry-mode
)
240 (condition-case error
245 (epa-file--encode-coding-string start coding-system
)
247 (setq start
(point-min)
249 (setq buffer
(current-buffer))
251 (insert-buffer-substring buffer start end
)
252 ;; Translate the region according to
253 ;; `buffer-file-format', as `write-region' would.
254 ;; We can't simply do `write-region' (into a
255 ;; temporary file) here, since it writes out
256 ;; decrypted contents.
257 (format-encode-buffer (with-current-buffer buffer
259 (epa-file--encode-coding-string (buffer-string)
261 (if (or (eq epa-file-select-keys t
)
262 (and (null epa-file-select-keys
)
263 (not (local-variable-p 'epa-file-encrypt-to
267 "Select recipients for encryption.
268 If no one is selected, symmetric encryption will be performed. "
270 (if epa-file-encrypt-to
271 (epg-list-keys context recipients
)))))
273 (epa-display-error context
)
274 (if (setq entry
(assoc file epa-file-passphrase-alist
))
276 (signal 'file-error
(cons "Opening output file" (cdr error
)))))
277 (epa-file-run-real-handler
279 (list string nil file append visit lockname mustbenew
))
280 (if (boundp 'last-coding-system-used
)
281 (setq last-coding-system-used coding-system
))
284 (setq buffer-file-name file
)
285 (set-visited-file-modtime))
288 (set-visited-file-modtime)
289 (setq buffer-file-name visit
))))
293 (message "Wrote `%s' (%d characters)" buffer-file-name
294 (cond ((null start
) (buffer-size))
295 ((stringp start
) (length start
))
296 (t (- end start
)))))))
297 (put 'write-region
'epa-file
'epa-file-write-region
)
299 (defun epa-file-select-keys ()
300 "Select recipients for encryption."
302 (setq-local epa-file-encrypt-to
305 (epg-sub-key-id (car (epg-key-sub-key-list key
))))
308 "Select recipients for encryption.
309 If no one is selected, symmetric encryption will be performed. "))))
312 (defun epa-file-enable ()
314 (if (memq epa-file-handler file-name-handler-alist
)
315 (message "`epa-file' already enabled")
316 (setq file-name-handler-alist
317 (cons epa-file-handler file-name-handler-alist
))
318 (add-hook 'find-file-hook
'epa-file-find-file-hook
)
319 (setq auto-mode-alist
(cons epa-file-auto-mode-alist-entry auto-mode-alist
))
320 (message "`epa-file' enabled")))
323 (defun epa-file-disable ()
325 (if (memq epa-file-handler file-name-handler-alist
)
327 (setq file-name-handler-alist
328 (delq epa-file-handler file-name-handler-alist
))
329 (remove-hook 'find-file-hook
'epa-file-find-file-hook
)
330 (setq auto-mode-alist
(delq epa-file-auto-mode-alist-entry
332 (message "`epa-file' disabled"))
333 (message "`epa-file' already disabled")))
337 ;;; epa-file.el ends here