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

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

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

;; 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 nil))
		(setcdr entry (copy-sequence passphrase))
		passphrase))))
    (epa-passphrase-callback-function context key-id nil)))

;;;###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 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))
	     (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
	    (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
ae940284	2	;; Copyright (C) 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
c154c0be MO	3
	4	;; Author: Daiki Ueno <ueno@unixuser.org>
	5	;; Keywords: PGP, GnuPG
	6
	7	;; This file is part of GNU Emacs.
	8
eb3fa2cf	9	;; GNU Emacs is free software: you can redistribute it and/or modify
c154c0be	10	;; it under the terms of the GNU General Public License as published by
eb3fa2cf GM	11	;; the Free Software Foundation, either version 3 of the License, or
eb3fa2cf GM	12	;; (at your option) any later version.
c154c0be MO	13
	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.
	18
	19	;; You should have received a copy of the GNU General Public License
eb3fa2cf	20	;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
c154c0be MO	21
	22	;;; Code:
	23
	24	(require 'epa)
3fe68728	25	(require 'epa-hook)
c154c0be MO	26
c154c0be MO	27	(defcustom epa-file-cache-passphrase-for-symmetric-encryption nil
b0f5fd2e DU	28	"If non-nil, cache passphrase for symmetric encryption.
	29
	30	For security reasons, this option is turned off by default and
0d19d151 DU	31	not recommended to use. Instead, consider using public-key
	32	encryption with gpg-agent which does the same job in a safer
	33	way."
c154c0be MO	34	:type 'boolean
	35	:group 'epa-file)
	36
c154c0be MO	37	(defcustom epa-file-select-keys nil
	38	"If non-nil, always asks user to select recipients."
	39	:type 'boolean
	40	:group 'epa-file)
	41
c154c0be MO	42	(defvar epa-file-passphrase-alist nil)
	43
	44	(eval-and-compile
	45	(if (fboundp 'encode-coding-string)
	46	(defalias 'epa-file--encode-coding-string 'encode-coding-string)
	47	(defalias 'epa-file--encode-coding-string 'identity)))
	48
	49	(eval-and-compile
	50	(if (fboundp 'decode-coding-string)
	51	(defalias 'epa-file--decode-coding-string 'decode-coding-string)
	52	(defalias 'epa-file--decode-coding-string 'identity)))
	53
c154c0be MO	54	(defun epa-file-passphrase-callback-function (context key-id file)
	55	(if (and epa-file-cache-passphrase-for-symmetric-encryption
	56	(eq key-id 'SYM))
	57	(progn
	58	(setq file (file-truename file))
	59	(let ((entry (assoc file epa-file-passphrase-alist))
	60	passphrase)
	61	(or (copy-sequence (cdr entry))
	62	(progn
	63	(unless entry
	64	(setq entry (list file)
	65	epa-file-passphrase-alist
	66	(cons entry
	67	epa-file-passphrase-alist)))
	68	(setq passphrase (epa-passphrase-callback-function context
	69	key-id nil))
	70	(setcdr entry (copy-sequence passphrase))
	71	passphrase))))
	72	(epa-passphrase-callback-function context key-id nil)))
	73
6f8a4190	74	;;;###autoload
c154c0be	75	(defun epa-file-handler (operation &rest args)
dbc9f96d GM	76	(save-match-data
	77	(let ((op (get operation 'epa-file)))
	78	(if op
	79	(apply op args)
	80	(epa-file-run-real-handler operation args)))))
	81
c154c0be MO	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)))
	89
	90	(defun epa-file-decode-and-insert (string file visit beg end replace)
	91	(if (fboundp 'decode-coding-inserted-region)
	92	(save-restriction
	93	(narrow-to-region (point) (point))
68a0d892 DU	94	(insert (if enable-multibyte-characters
	95	(string-to-multibyte string)
	96	string))
c154c0be MO	97	(decode-coding-inserted-region
	98	(point-min) (point-max)
	99	(substring file 0 (string-match epa-file-name-regexp file))
68a0d892	100	visit beg end replace))
c154c0be MO	101	(insert (epa-file--decode-coding-string string (or coding-system-for-read
	102	'undecided)))))
	103
	104	(defvar last-coding-system-used)
	105	(defun epa-file-insert-file-contents (file &optional visit beg end replace)
	106	(barf-if-buffer-read-only)
	107	(if (and visit (or beg end))
	108	(error "Attempt to visit less than an entire file"))
	109	(setq file (expand-file-name file))
	110	(let* ((local-copy
6ea97db8	111	(condition-case nil
c154c0be MO	112	(epa-file-run-real-handler #'file-local-copy (list file))
	113	(error)))
	114	(local-file (or local-copy file))
	115	(context (epg-make-context))
	116	string length entry)
2cb35a56 DU	117	(if visit
2cb35a56 DU	118	(setq buffer-file-name file))
c154c0be MO	119	(epg-context-set-passphrase-callback
	120	context
	121	(cons #'epa-file-passphrase-callback-function
	122	local-file))
	123	(epg-context-set-progress-callback context
	124	#'epa-progress-callback-function)
	125	(unwind-protect
	126	(progn
	127	(if replace
	128	(goto-char (point-min)))
	129	(condition-case error
	130	(setq string (epg-decrypt-file context local-file nil))
	131	(error
	132	(if (setq entry (assoc file epa-file-passphrase-alist))
	133	(setcdr entry nil))
	134	(signal 'file-error
	135	(cons "Opening input file" (cdr error)))))
	136	(make-local-variable 'epa-file-encrypt-to)
	137	(setq epa-file-encrypt-to
	138	(mapcar #'car (epg-context-result-for context 'encrypted-to)))
	139	(if (or beg end)
	140	(setq string (substring string (or beg 0) end)))
	141	(save-excursion
	142	(save-restriction
	143	(narrow-to-region (point) (point))
	144	(epa-file-decode-and-insert string file visit beg end replace)
	145	(setq length (- (point-max) (point-min))))
	146	(if replace
8e3efc87	147	(delete-region (point) (point-max)))
2cb35a56 DU	148	(if visit
2cb35a56 DU	149	(set-visited-file-modtime))))
c154c0be MO	150	(if (and local-copy
	151	(file-exists-p local-copy))
	152	(delete-file local-copy)))
	153	(list file length)))
	154	(put 'insert-file-contents 'epa-file 'epa-file-insert-file-contents)
	155
	156	(defun epa-file-write-region (start end file &optional append visit lockname
	157	mustbenew)
	158	(if append
5a0c3f56	159	(error "Can't append to the file"))
c154c0be MO	160	(setq file (expand-file-name file))
	161	(let* ((coding-system (or coding-system-for-write
	162	(if (fboundp 'select-safe-coding-system)
	163	;; This is needed since Emacs 22 has
	164	;; no-conversion setting for *.gpg in
	165	;; `auto-coding-alist'.
	166	(let ((buffer-file-name
	167	(file-name-sans-extension file)))
	168	(select-safe-coding-system
	169	(point-min) (point-max)))
	170	buffer-file-coding-system)))
	171	(context (epg-make-context))
	172	(coding-system-for-write 'binary)
	173	string entry
	174	(recipients
	175	(cond
	176	((listp epa-file-encrypt-to) epa-file-encrypt-to)
	177	((stringp epa-file-encrypt-to) (list epa-file-encrypt-to)))))
	178	(epg-context-set-passphrase-callback
	179	context
	180	(cons #'epa-file-passphrase-callback-function
	181	file))
	182	(epg-context-set-progress-callback context
	183	#'epa-progress-callback-function)
	184	(epg-context-set-armor context epa-armor)
	185	(condition-case error
	186	(setq string
	187	(epg-encrypt-string
	188	context
	189	(if (stringp start)
	190	(epa-file--encode-coding-string start coding-system)
6843296d	191	(unless start
437eedba DU	192	(setq start (point-min)
437eedba DU	193	end (point-max)))
c154c0be MO	194	(epa-file--encode-coding-string (buffer-substring start end)
	195	coding-system))
	196	(if (or epa-file-select-keys
	197	(not (local-variable-p 'epa-file-encrypt-to
	198	(current-buffer))))
	199	(epa-select-keys
	200	context
	201	"Select recipents for encryption.
	202	If no one is selected, symmetric encryption will be performed. "
	203	recipients)
	204	(if epa-file-encrypt-to
	205	(epg-list-keys context recipients)))))
	206	(error
	207	(if (setq entry (assoc file epa-file-passphrase-alist))
	208	(setcdr entry nil))
	209	(signal 'file-error (cons "Opening output file" (cdr error)))))
	210	(epa-file-run-real-handler
	211	#'write-region
	212	(list string nil file append visit lockname mustbenew))
	213	(if (boundp 'last-coding-system-used)
	214	(setq last-coding-system-used coding-system))
	215	(if (eq visit t)
	216	(progn
	217	(setq buffer-file-name file)
	218	(set-visited-file-modtime))
	219	(if (stringp visit)
	220	(progn
	221	(set-visited-file-modtime)
	222	(setq buffer-file-name visit))))
	223	(if (or (eq visit t)
	224	(eq visit nil)
	225	(stringp visit))
	226	(message "Wrote %s" buffer-file-name))))
	227	(put 'write-region 'epa-file 'epa-file-write-region)
	228
c154c0be MO	229	(defun epa-file-select-keys ()
	230	"Select recipients for encryption."
	231	(interactive)
	232	(make-local-variable 'epa-file-encrypt-to)
	233	(setq epa-file-encrypt-to
fef7aa9e MO	234	(mapcar
	235	(lambda (key)
	236	(epg-sub-key-id (car (epg-key-sub-key-list key))))
c154c0be MO	237	(epa-select-keys
	238	(epg-make-context)
	239	"Select recipents for encryption.
fef7aa9e	240	If no one is selected, symmetric encryption will be performed. "))))
c154c0be MO	241
	242	;;;###autoload
	243	(defun epa-file-enable ()
	244	(interactive)
	245	(if (memq epa-file-handler file-name-handler-alist)
	246	(message "`epa-file' already enabled")
	247	(setq file-name-handler-alist
	248	(cons epa-file-handler file-name-handler-alist))
bfeee9d1	249	(add-hook 'find-file-hook 'epa-file-find-file-hook)
c154c0be MO	250	(setq auto-mode-alist (cons epa-file-auto-mode-alist-entry auto-mode-alist))
	251	(message "`epa-file' enabled")))
	252
	253	;;;###autoload
	254	(defun epa-file-disable ()
	255	(interactive)
	256	(if (memq epa-file-handler file-name-handler-alist)
	257	(progn
	258	(setq file-name-handler-alist
	259	(delq epa-file-handler file-name-handler-alist))
bfeee9d1	260	(remove-hook 'find-file-hook 'epa-file-find-file-hook)
c154c0be MO	261	(setq auto-mode-alist (delq epa-file-auto-mode-alist-entry
	262	auto-mode-alist))
	263	(message "`epa-file' disabled"))
	264	(message "`epa-file' already disabled")))
	265
	266	(provide 'epa-file)
	267
37b77401	268	;; arch-tag: 5715152f-0eb1-4dbc-9008-07098775314d
c154c0be	269	;;; epa-file.el ends here