[bpt/emacs.git] / lisp / epa-file.el

;;; epa-file.el --- the EasyPG Assistant, transparent file encryption
;; Copyright (C) 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.

;; Author: Daiki Ueno <ueno@unixuser.org>
;; Keywords: PGP, GnuPG
;; Package: epa

;; 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 <http://www.gnu.org/licenses/>.

;;; Code:

(require 'epa)
(require 'epa-hook)

(defcustom epa-file-cache-passphrase-for-symmetric-encryption nil
  "If non-nil, cache passphrase for symmetric encryption.

For security reasons, this option is turned off by default and
not recommended to use.  Instead, consider using public-key
encryption with gpg-agent which does the same job in a safer
way."
  :type 'boolean
  :group 'epa-file)

(defcustom epa-file-select-keys nil
  "If non-nil, always asks user to select recipients."
  :type 'boolean
  :group 'epa-file)

(defvar epa-file-passphrase-alist nil)

(eval-and-compile
  (if (fboundp 'encode-coding-string)
      (defalias 'epa-file--encode-coding-string 'encode-coding-string)
    (defalias 'epa-file--encode-coding-string 'identity)))

(eval-and-compile
  (if (fboundp 'decode-coding-string)
      (defalias 'epa-file--decode-coding-string 'decode-coding-string)
    (defalias 'epa-file--decode-coding-string 'identity)))

(defun epa-file-passphrase-callback-function (context key-id file)
  (if (and epa-file-cache-passphrase-for-symmetric-encryption
	   (eq key-id 'SYM))
      (progn
	(setq file (file-truename file))
	(let ((entry (assoc file epa-file-passphrase-alist))
	      passphrase)
	  (or (copy-sequence (cdr entry))
	      (progn
		(unless entry
		  (setq entry (list file)
			epa-file-passphrase-alist
			(cons entry
			      epa-file-passphrase-alist)))
		(setq passphrase (epa-passphrase-callback-function context
								   key-id
								   file))
		(setcdr entry (copy-sequence passphrase))
		passphrase))))
    (epa-passphrase-callback-function context key-id file)))

;;;###autoload
(defun epa-file-handler (operation &rest args)
  (save-match-data
    (let ((op (get operation 'epa-file)))
      (if op
  	  (apply op args)
  	(epa-file-run-real-handler operation args)))))

(defun epa-file-run-real-handler (operation args)
  (let ((inhibit-file-name-handlers
	 (cons 'epa-file-handler
	       (and (eq inhibit-file-name-operation operation)
		    inhibit-file-name-handlers)))
	(inhibit-file-name-operation operation))
    (apply operation args)))

(defun epa-file-decode-and-insert (string file visit beg end replace)
  (if (fboundp 'decode-coding-inserted-region)
      (save-restriction
	(narrow-to-region (point) (point))
	(insert (if enable-multibyte-characters
		    (string-to-multibyte string)
		  string))
	  (decode-coding-inserted-region
	   (point-min) (point-max)
	   (substring file 0 (string-match epa-file-name-regexp file))
	 visit beg end replace))
    (insert (epa-file--decode-coding-string string (or coding-system-for-read
						       'undecided)))))

(defvar epa-file-error nil)
(defun epa-file--find-file-not-found-function ()
  (let ((error epa-file-error))
    (save-window-excursion
      (kill-buffer))
    (signal 'file-error
	    (cons "Opening input file" (cdr error)))))

(defvar last-coding-system-used)
(defun epa-file-insert-file-contents (file &optional visit beg end replace)
  (barf-if-buffer-read-only)
  (if (and visit (or beg end))
      (error "Attempt to visit less than an entire file"))
  (setq file (expand-file-name file))
  (let* ((local-copy
	  (condition-case nil
	      (epa-file-run-real-handler #'file-local-copy (list file))
	    (error)))
	 (local-file (or local-copy file))
	 (context (epg-make-context))
	 string length entry)
    (if visit
	(setq buffer-file-name file))
    (epg-context-set-passphrase-callback
     context
     (cons #'epa-file-passphrase-callback-function
	   local-file))
    (epg-context-set-progress-callback context
				       #'epa-progress-callback-function)
    (unwind-protect
	(progn
	  (if replace
	      (goto-char (point-min)))
	  (condition-case error
	      (setq string (epg-decrypt-file context local-file nil))
	    (error
	     (if (setq entry (assoc file epa-file-passphrase-alist))
		 (setcdr entry nil))
	     ;; Hack to prevent find-file from opening empty buffer
	     ;; when decryption failed (bug#6568).  See the place
	     ;; where `find-file-not-found-functions' are called in
	     ;; `find-file-noselect-1'.
	     (when (file-exists-p local-file)
	       (make-local-variable 'epa-file-error)
	       (setq epa-file-error error)
	       (add-hook 'find-file-not-found-functions
			 'epa-file--find-file-not-found-function
			 nil t))
	     (signal 'file-error
		     (cons "Opening input file" (cdr error)))))
	  (make-local-variable 'epa-file-encrypt-to)
	  (setq epa-file-encrypt-to
		(mapcar #'car (epg-context-result-for context 'encrypted-to)))
	  (if (or beg end)
	      (setq string (substring string (or beg 0) end)))
	  (save-excursion
	    ;; If visiting, bind off buffer-file-name so that
	    ;; file-locking will not ask whether we should
	    ;; really edit the buffer.
	    (let ((buffer-file-name
		   (if visit nil buffer-file-name)))
	      (save-restriction
		(narrow-to-region (point) (point))
		(epa-file-decode-and-insert string file visit beg end replace)
		(setq length (- (point-max) (point-min))))
	      (if replace
		  (delete-region (point) (point-max))))
	    (if visit
		(set-visited-file-modtime))))
      (if (and local-copy
	       (file-exists-p local-copy))
	  (delete-file local-copy)))
    (list file length)))
(put 'insert-file-contents 'epa-file 'epa-file-insert-file-contents)

(defun epa-file-write-region (start end file &optional append visit lockname
				    mustbenew)
  (if append
      (error "Can't append to the file"))
  (setq file (expand-file-name file))
  (let* ((coding-system (or coding-system-for-write
			    (if (fboundp 'select-safe-coding-system)
				;; This is needed since Emacs 22 has
				;; no-conversion setting for *.gpg in
				;; `auto-coding-alist'.
			        (let ((buffer-file-name
				       (file-name-sans-extension file)))
				  (select-safe-coding-system
				   (point-min) (point-max)))
			      buffer-file-coding-system)))
	 (context (epg-make-context))
	 (coding-system-for-write 'binary)
	 string entry
	 (recipients
	  (cond
	   ((listp epa-file-encrypt-to) epa-file-encrypt-to)
	   ((stringp epa-file-encrypt-to) (list epa-file-encrypt-to)))))
    (epg-context-set-passphrase-callback
     context
     (cons #'epa-file-passphrase-callback-function
	   file))
    (epg-context-set-progress-callback context
				       #'epa-progress-callback-function)
    (epg-context-set-armor context epa-armor)
    (condition-case error
	(setq string
	      (epg-encrypt-string
	       context
	       (if (stringp start)
		   (epa-file--encode-coding-string start coding-system)
		 (unless start
		   (setq start (point-min)
			 end (point-max)))
		 (epa-file--encode-coding-string (buffer-substring start end)
						 coding-system))
	       (if (or epa-file-select-keys
		       (not (local-variable-p 'epa-file-encrypt-to
					      (current-buffer))))
		   (epa-select-keys
		    context
		    "Select recipents for encryption.
If no one is selected, symmetric encryption will be performed.  "
		    recipients)
		 (if epa-file-encrypt-to
		     (epg-list-keys context recipients)))))
      (error
       (if (setq entry (assoc file epa-file-passphrase-alist))
	   (setcdr entry nil))
       (signal 'file-error (cons "Opening output file" (cdr error)))))
    (epa-file-run-real-handler
     #'write-region
     (list string nil file append visit lockname mustbenew))
    (if (boundp 'last-coding-system-used)
	(setq last-coding-system-used coding-system))
    (if (eq visit t)
	(progn
	  (setq buffer-file-name file)
	  (set-visited-file-modtime))
      (if (stringp visit)
	  (progn
	    (set-visited-file-modtime)
	    (setq buffer-file-name visit))))
    (if (or (eq visit t)
	    (eq visit nil)
	    (stringp visit))
	(message "Wrote %s" buffer-file-name))))
(put 'write-region 'epa-file 'epa-file-write-region)

(defun epa-file-select-keys ()
  "Select recipients for encryption."
  (interactive)
  (make-local-variable 'epa-file-encrypt-to)
  (setq epa-file-encrypt-to
	(mapcar
	 (lambda (key)
	   (epg-sub-key-id (car (epg-key-sub-key-list key))))
	(epa-select-keys
	 (epg-make-context)
	 "Select recipents for encryption.
If no one is selected, symmetric encryption will be performed.  "))))

;;;###autoload
(defun epa-file-enable ()
  (interactive)
  (if (memq epa-file-handler file-name-handler-alist)
      (message "`epa-file' already enabled")
    (setq file-name-handler-alist
	  (cons epa-file-handler file-name-handler-alist))
    (add-hook 'find-file-hook 'epa-file-find-file-hook)
    (setq auto-mode-alist (cons epa-file-auto-mode-alist-entry auto-mode-alist))
    (message "`epa-file' enabled")))

;;;###autoload
(defun epa-file-disable ()
  (interactive)
  (if (memq epa-file-handler file-name-handler-alist)
      (progn
	(setq file-name-handler-alist
	      (delq epa-file-handler file-name-handler-alist))
	(remove-hook 'find-file-hook 'epa-file-find-file-hook)
	(setq auto-mode-alist (delq epa-file-auto-mode-alist-entry
				    auto-mode-alist))
	(message "`epa-file' disabled"))
    (message "`epa-file' already disabled")))

(provide 'epa-file)

;; arch-tag: 5715152f-0eb1-4dbc-9008-07098775314d
;;; epa-file.el ends here
Commit	Line	Data
c154c0be	1	;;; epa-file.el --- the EasyPG Assistant, transparent file encryption
114f9c96	2	;; Copyright (C) 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
c154c0be MO	3
	4	;; Author: Daiki Ueno <ueno@unixuser.org>
	5	;; Keywords: PGP, GnuPG
bd78fa1d	6	;; Package: epa
c154c0be MO	7
	8	;; This file is part of GNU Emacs.
	9
eb3fa2cf	10	;; GNU Emacs is free software: you can redistribute it and/or modify
c154c0be	11	;; it under the terms of the GNU General Public License as published by
eb3fa2cf GM	12	;; the Free Software Foundation, either version 3 of the License, or
eb3fa2cf GM	13	;; (at your option) any later version.
c154c0be MO	14
	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.
	19
	20	;; You should have received a copy of the GNU General Public License
eb3fa2cf	21	;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
c154c0be MO	22
	23	;;; Code:
	24
	25	(require 'epa)
3fe68728	26	(require 'epa-hook)
c154c0be MO	27
c154c0be MO	28	(defcustom epa-file-cache-passphrase-for-symmetric-encryption nil
b0f5fd2e DU	29	"If non-nil, cache passphrase for symmetric encryption.
	30
	31	For security reasons, this option is turned off by default and
0d19d151 DU	32	not recommended to use. Instead, consider using public-key
	33	encryption with gpg-agent which does the same job in a safer
	34	way."
c154c0be MO	35	:type 'boolean
	36	:group 'epa-file)
	37
c154c0be MO	38	(defcustom epa-file-select-keys nil
	39	"If non-nil, always asks user to select recipients."
	40	:type 'boolean
	41	:group 'epa-file)
	42
c154c0be MO	43	(defvar epa-file-passphrase-alist nil)
	44
	45	(eval-and-compile
	46	(if (fboundp 'encode-coding-string)
	47	(defalias 'epa-file--encode-coding-string 'encode-coding-string)
	48	(defalias 'epa-file--encode-coding-string 'identity)))
	49
	50	(eval-and-compile
	51	(if (fboundp 'decode-coding-string)
	52	(defalias 'epa-file--decode-coding-string 'decode-coding-string)
	53	(defalias 'epa-file--decode-coding-string 'identity)))
	54
c154c0be MO	55	(defun epa-file-passphrase-callback-function (context key-id file)
	56	(if (and epa-file-cache-passphrase-for-symmetric-encryption
	57	(eq key-id 'SYM))
	58	(progn
	59	(setq file (file-truename file))
	60	(let ((entry (assoc file epa-file-passphrase-alist))
	61	passphrase)
	62	(or (copy-sequence (cdr entry))
	63	(progn
	64	(unless entry
	65	(setq entry (list file)
	66	epa-file-passphrase-alist
	67	(cons entry
	68	epa-file-passphrase-alist)))
	69	(setq passphrase (epa-passphrase-callback-function context
446b12da DU	70	key-id
446b12da DU	71	file))
c154c0be MO	72	(setcdr entry (copy-sequence passphrase))
c154c0be MO	73	passphrase))))
446b12da	74	(epa-passphrase-callback-function context key-id file)))
c154c0be	75
6f8a4190	76	;;;###autoload
c154c0be	77	(defun epa-file-handler (operation &rest args)
dbc9f96d GM	78	(save-match-data
	79	(let ((op (get operation 'epa-file)))
	80	(if op
	81	(apply op args)
	82	(epa-file-run-real-handler operation args)))))
	83
c154c0be MO	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)))
	91
	92	(defun epa-file-decode-and-insert (string file visit beg end replace)
	93	(if (fboundp 'decode-coding-inserted-region)
	94	(save-restriction
	95	(narrow-to-region (point) (point))
68a0d892 DU	96	(insert (if enable-multibyte-characters
	97	(string-to-multibyte string)
	98	string))
c154c0be MO	99	(decode-coding-inserted-region
	100	(point-min) (point-max)
	101	(substring file 0 (string-match epa-file-name-regexp file))
68a0d892	102	visit beg end replace))
c154c0be MO	103	(insert (epa-file--decode-coding-string string (or coding-system-for-read
	104	'undecided)))))
	105
c0397930 DU	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
	110	(kill-buffer))
	111	(signal 'file-error
	112	(cons "Opening input file" (cdr error)))))
	113
c154c0be MO	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))
	120	(let* ((local-copy
6ea97db8	121	(condition-case nil
c154c0be MO	122	(epa-file-run-real-handler #'file-local-copy (list file))
	123	(error)))
	124	(local-file (or local-copy file))
	125	(context (epg-make-context))
	126	string length entry)
2cb35a56 DU	127	(if visit
2cb35a56 DU	128	(setq buffer-file-name file))
c154c0be MO	129	(epg-context-set-passphrase-callback
	130	context
	131	(cons #'epa-file-passphrase-callback-function
	132	local-file))
	133	(epg-context-set-progress-callback context
	134	#'epa-progress-callback-function)
	135	(unwind-protect
	136	(progn
	137	(if replace
	138	(goto-char (point-min)))
	139	(condition-case error
	140	(setq string (epg-decrypt-file context local-file nil))
	141	(error
	142	(if (setq entry (assoc file epa-file-passphrase-alist))
	143	(setcdr entry nil))
192cfe77 DU	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'.
4f195cf7	148	(when (file-exists-p local-file)
4f195cf7 DU	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
	153	nil t))
c154c0be MO	154	(signal 'file-error
	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)))
	159	(if (or beg end)
	160	(setq string (substring string (or beg 0) end)))
	161	(save-excursion
c5fe4acb DU	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)))
	167	(save-restriction
	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))))
	171	(if replace
	172	(delete-region (point) (point-max))))
2cb35a56 DU	173	(if visit
2cb35a56 DU	174	(set-visited-file-modtime))))
c154c0be MO	175	(if (and local-copy
	176	(file-exists-p local-copy))
	177	(delete-file local-copy)))
	178	(list file length)))
	179	(put 'insert-file-contents 'epa-file 'epa-file-insert-file-contents)
	180
	181	(defun epa-file-write-region (start end file &optional append visit lockname
	182	mustbenew)
	183	(if append
5a0c3f56	184	(error "Can't append to the file"))
c154c0be MO	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)
	198	string entry
	199	(recipients
	200	(cond
	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
	204	context
	205	(cons #'epa-file-passphrase-callback-function
	206	file))
	207	(epg-context-set-progress-callback context
	208	#'epa-progress-callback-function)
	209	(epg-context-set-armor context epa-armor)
	210	(condition-case error
	211	(setq string
	212	(epg-encrypt-string
	213	context
	214	(if (stringp start)
	215	(epa-file--encode-coding-string start coding-system)
6843296d	216	(unless start
437eedba DU	217	(setq start (point-min)
437eedba DU	218	end (point-max)))
c154c0be MO	219	(epa-file--encode-coding-string (buffer-substring start end)
	220	coding-system))
	221	(if (or epa-file-select-keys
	222	(not (local-variable-p 'epa-file-encrypt-to
	223	(current-buffer))))
	224	(epa-select-keys
	225	context
	226	"Select recipents for encryption.
	227	If no one is selected, symmetric encryption will be performed. "
	228	recipients)
	229	(if epa-file-encrypt-to
	230	(epg-list-keys context recipients)))))
	231	(error
	232	(if (setq entry (assoc file epa-file-passphrase-alist))
	233	(setcdr entry nil))
	234	(signal 'file-error (cons "Opening output file" (cdr error)))))
	235	(epa-file-run-real-handler
	236	#'write-region
	237	(list string nil file append visit lockname mustbenew))
	238	(if (boundp 'last-coding-system-used)
	239	(setq last-coding-system-used coding-system))
	240	(if (eq visit t)
	241	(progn
	242	(setq buffer-file-name file)
	243	(set-visited-file-modtime))
	244	(if (stringp visit)
	245	(progn
	246	(set-visited-file-modtime)
	247	(setq buffer-file-name visit))))
	248	(if (or (eq visit t)
	249	(eq visit nil)
	250	(stringp visit))
	251	(message "Wrote %s" buffer-file-name))))
	252	(put 'write-region 'epa-file 'epa-file-write-region)
	253
c154c0be MO	254	(defun epa-file-select-keys ()
	255	"Select recipients for encryption."
	256	(interactive)
	257	(make-local-variable 'epa-file-encrypt-to)
	258	(setq epa-file-encrypt-to
fef7aa9e MO	259	(mapcar
	260	(lambda (key)
	261	(epg-sub-key-id (car (epg-key-sub-key-list key))))
c154c0be MO	262	(epa-select-keys
	263	(epg-make-context)
	264	"Select recipents for encryption.
fef7aa9e	265	If no one is selected, symmetric encryption will be performed. "))))
c154c0be MO	266
	267	;;;###autoload
	268	(defun epa-file-enable ()
	269	(interactive)
	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))
bfeee9d1	274	(add-hook 'find-file-hook 'epa-file-find-file-hook)
c154c0be MO	275	(setq auto-mode-alist (cons epa-file-auto-mode-alist-entry auto-mode-alist))
	276	(message "`epa-file' enabled")))
	277
	278	;;;###autoload
	279	(defun epa-file-disable ()
	280	(interactive)
	281	(if (memq epa-file-handler file-name-handler-alist)
	282	(progn
	283	(setq file-name-handler-alist
	284	(delq epa-file-handler file-name-handler-alist))
bfeee9d1	285	(remove-hook 'find-file-hook 'epa-file-find-file-hook)
c154c0be MO	286	(setq auto-mode-alist (delq epa-file-auto-mode-alist-entry
	287	auto-mode-alist))
	288	(message "`epa-file' disabled"))
	289	(message "`epa-file' already disabled")))
	290
	291	(provide 'epa-file)
	292
37b77401	293	;; arch-tag: 5715152f-0eb1-4dbc-9008-07098775314d
c154c0be	294	;;; epa-file.el ends here