1 ;;; encrypt.el --- file encryption routines
2 ;; Copyright (C) 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
4 ;; Author: Teodor Zlatanov <tzz@lifelogs.com>
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 2, or (at your option)
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; see the file COPYING. If not, write to the
22 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
23 ;; Boston, MA 02111-1307, USA.
27 ;;; This module addresses data encryption. Page breaks are used for
28 ;;; grouping declarations and documentation relating to each
29 ;;; particular aspect.
35 (autoload 'password-read "password")
36 ;; The following section is needed since T-gnus won't load password.el
37 ;; by way of pgg.el at the compile time.
38 (autoload 'password-read-and-add "password")
39 (autoload 'password-cache-remove "password")
40 (defvar password-cache-expiry))
42 (defgroup encrypt '((password-cache custom-variable)
43 (password-cache-expiry custom-variable))
44 "File encryption configuration."
47 (defcustom encrypt-file-alist nil
48 "List of file names or regexes matched with encryptions.
53 (encrypt-xor \"Semi-Secret\")))"
56 (list :tag "Encryption entry"
57 (radio :tag "What to encrypt"
58 (file :tag "Filename")
59 (regexp :tag "Regular expression match"))
60 (radio :tag "How to encrypt it"
63 (const :tag "GPG Program" gpg)
64 (radio :tag "Choose a cipher"
65 (const :tag "3DES Encryption" "3DES")
66 (const :tag "CAST5 Encryption" "CAST5")
67 (const :tag "Blowfish Encryption" "BLOWFISH")
68 (const :tag "AES Encryption" "AES")
69 (const :tag "AES192 Encryption" "AES192")
70 (const :tag "AES256 Encryption" "AES256")
71 (const :tag "Twofish Encryption" "TWOFISH")
72 (string :tag "Cipher Name")))
74 :tag "Built-in simple XOR"
75 (const :tag "XOR Encryption" encrypt-xor)
76 (string :tag "XOR Cipher Value (seed value)")))))
79 ;; TODO: now, load gencrypt.el and if successful, modify the
80 ;; custom-type of encrypt-file-alist to add the gencrypt.el options
82 ;; (plist-get (symbol-plist 'encrypt-file-alist) 'custom-type)
85 (defcustom encrypt-gpg-path (executable-find "gpg")
86 "Path to the GPG program."
88 (file :tag "Location of the GPG executable")
89 (const :tag "GPG is not installed" nil))
92 (defvar encrypt-temp-prefix "encrypt"
93 "Prefix for temporary filenames")
96 (defun encrypt-find-model (filename)
97 "Given a filename, find a encrypt-file-alist entry"
98 (dolist (entry encrypt-file-alist)
99 (let ((match (nth 0 entry))
100 (model (nth 1 entry)))
101 (when (or (eq match filename)
102 (string-match match filename))
106 (defun encrypt-insert-file-contents (file &optional model)
107 "Decrypt FILE into the current buffer."
108 (interactive "fFile to insert: ")
109 (let* ((model (or model (encrypt-find-model file)))
110 (method (nth 0 model))
111 (cipher (nth 1 model))
112 (password-key (format "encrypt-password-%s-%s %s"
113 (symbol-name method) cipher file))
115 (password-read-and-add
116 (format "%s password for cipher %s? "
117 (symbol-name method) cipher)
119 (buffer-file-coding-system 'binary)
120 (coding-system-for-read 'binary)
123 ;; note we only insert-file-contents if the method is known to be valid
126 (insert-file-contents file)
127 (setq outdata (encrypt-gpg-decode-buffer passphrase cipher)))
128 ((eq method 'encrypt-xor)
129 (insert-file-contents file)
130 (setq outdata (encrypt-xor-decode-buffer passphrase cipher))))
134 (gnus-message 9 "%s was decrypted with %s (cipher %s)"
135 file (symbol-name method) cipher)
136 (delete-region (point-min) (point-max))
137 (goto-char (point-min))
139 ;; the decryption failed, alas
140 (password-cache-remove password-key)
141 (gnus-error 5 "%s was NOT decrypted with %s (cipher %s)"
142 file (symbol-name method) cipher))))
144 (defun encrypt-get-file-contents (file &optional model)
145 "Decrypt FILE and return the contents."
146 (interactive "fFile to decrypt: ")
148 (encrypt-insert-file-contents file model)
151 (defun encrypt-put-file-contents (file data &optional model)
152 "Encrypt the DATA to FILE, then continue normally."
155 (encrypt-write-file-contents file model)))
157 (defun encrypt-write-file-contents (file &optional model)
158 "Encrypt the current buffer to FILE, then continue normally."
159 (interactive "fFile to write: ")
160 (let* ((model (or model (encrypt-find-model file)))
161 (method (nth 0 model))
162 (cipher (nth 1 model))
163 (password-key (format "encrypt-password-%s-%s %s"
164 (symbol-name method) cipher file))
167 (format "%s password for cipher %s? "
168 (symbol-name method) cipher)
174 (setq outdata (encrypt-gpg-encode-buffer passphrase cipher)))
175 ((eq method 'encrypt-xor)
176 (setq outdata (encrypt-xor-encode-buffer passphrase cipher))))
180 (gnus-message 9 "%s was encrypted with %s (cipher %s)"
181 file (symbol-name method) cipher)
182 (delete-region (point-min) (point-max))
183 (goto-char (point-min))
185 ;; do not confirm overwrites
186 (write-file file nil))
187 ;; the decryption failed, alas
188 (password-cache-remove password-key)
189 (gnus-error 5 "%s was NOT encrypted with %s (cipher %s)"
190 file (symbol-name method) cipher))))
192 (defun encrypt-xor-encode-buffer (passphrase cipher)
193 (encrypt-xor-process-buffer passphrase cipher t))
195 (defun encrypt-xor-decode-buffer (passphrase cipher)
196 (encrypt-xor-process-buffer passphrase cipher nil))
198 (defun encrypt-xor-process-buffer (passphrase
201 "Given PASSPHRASE, xor-encode or decode the contents of the current buffer."
202 (let* ((bs (buffer-substring-no-properties (point-min) (point-max)))
203 ;; passphrase-sum is a simple additive checksum of the
204 ;; passphrase and the cipher
206 (when (stringp passphrase)
207 (apply '+ (append cipher passphrase nil))))
213 (dolist (x (append bs nil))
214 (setq new-list (cons (logxor x passphrase-sum) new-list)))
217 (insert (format "%d " x))))
219 (setq new-list (reverse (split-string bs)))
221 (setq x (string-to-number x))
222 (insert (format "%c" (logxor x passphrase-sum))))))
223 (buffer-substring-no-properties (point-min) (point-max)))))
225 (defun encrypt-gpg-encode-buffer (passphrase cipher)
226 (encrypt-gpg-process-buffer passphrase cipher t))
228 (defun encrypt-gpg-decode-buffer (passphrase cipher)
229 (encrypt-gpg-process-buffer passphrase cipher nil))
231 (defun encrypt-gpg-process-buffer (passphrase
234 "With PASSPHRASE, use GPG to encode or decode the current buffer."
235 (let* ((program encrypt-gpg-path)
236 (input (buffer-substring-no-properties (point-min) (point-max)))
237 (temp-maker (if (fboundp 'make-temp-file)
240 (temp-file (funcall temp-maker encrypt-temp-prefix))
241 (default-enable-multibyte-characters nil)
242 (args `("--cipher-algo" ,cipher
245 "--passphrase-fd" "0"
247 exit-status exit-data)
258 (insert passphrase "\n"))
261 (apply #'call-process-region (point-min) (point-max) program
262 t `(t ,temp-file) nil args))
263 (if (equal exit-status 0)
265 (buffer-substring-no-properties (point-min) (point-max)))
267 (when (file-exists-p temp-file)
268 (insert-file-contents temp-file))
269 (gnus-error 5 (format "%s exited abnormally: '%s' [%s]"
270 program exit-status (buffer-string)))))
271 (delete-file temp-file))
272 (gnus-error 5 "GPG is not installed."))
276 ;;; encrypt.el ends here