1 ;;; smime.el --- S/MIME interface.
3 ;; Copyright (C) 1999 Daiki Ueno
5 ;; Author: Daiki Ueno <ueno@ueda.info.waseda.ac.jp>
7 ;; Keywords: S/MIME, OpenSSL
9 ;; This file is part of SEMI (Secure Emacs MIME Interface).
11 ;; This program is free software; you can redistribute it and/or
12 ;; modify it under the terms of the GNU General Public License as
13 ;; published by the Free Software Foundation; either version 2, or (at
14 ;; your option) any later version.
16 ;; This program is distributed in the hope that it will be useful, but
17 ;; WITHOUT ANY WARRANTY; without even the implied warranty of
18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
19 ;; General Public License for more details.
21 ;; You should have received a copy of the GNU General Public License
22 ;; along with GNU Emacs; see the file COPYING. If not, write to the
23 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
24 ;; Boston, MA 02111-1307, USA.
29 ;; This module is based on
31 ;; [SMIMEV3] RFC 2633: "S/MIME Version 3 Message Specification"
32 ;; by Crocker, D., Flanigan, B., Hoffman, P., Housley, R.,
33 ;; Pawling, J. and Schaad, J. (1999/06)
35 ;; [SMIMEV2] RFC 2311: "S/MIME Version 2 Message Specification"
36 ;; by Dusse, S., Hoffman, P., Ramsdell, B., Lundblade, L.
37 ;; and L. Repka. (1998/03)
47 (defcustom smime-program "smime"
48 "The S/MIME executable."
52 (defcustom smime-shell-file-name "/bin/sh"
53 "File name to load inferior shells from. Bourne shell or its equivalent
54 \(not tcsh) is needed for \"2>\"."
58 (defcustom smime-shell-command-switch "-c"
59 "Switch used to have the shell execute its command line argument."
63 (defcustom smime-x509-program
64 (let ((file (exec-installed-p "openssl")))
65 (and file (list file "x509" "-noout")))
66 "External program for x509 parser."
70 (defcustom smime-cache-passphrase t
75 (defcustom smime-certificate-directory "~/.w3/certs"
76 "Certificate directory."
80 (defcustom smime-public-key-file nil
85 (defcustom smime-private-key-file nil
90 (defvar smime-errors-buffer " *S/MIME errors*")
91 (defvar smime-output-buffer " *S/MIME output*")
93 ;;; @ utility functions
95 (put 'smime-process-when-success 'lisp-indent-function 0)
97 (defmacro smime-process-when-success (&rest body)
98 `(with-current-buffer smime-output-buffer
99 (if (zerop (buffer-size)) nil ,@body t)))
101 (defvar smime-passphrase-cache-expiry 16)
102 (defvar smime-passphrase-cache (make-vector 7 0))
104 (defvar smime-read-passphrase nil)
105 (defun smime-read-passphrase (prompt &optional key)
106 (if (not smime-read-passphrase)
107 (if (functionp 'read-passwd)
108 (setq smime-read-passphrase 'read-passwd)
109 (if (load "passwd" t)
110 (setq smime-read-passphrase 'read-passwd)
111 (autoload 'ange-ftp-read-passwd "ange-ftp")
112 (setq smime-read-passphrase 'ange-ftp-read-passwd))))
113 (or (and smime-cache-passphrase
114 (symbol-value (intern-soft key smime-passphrase-cache)))
115 (funcall smime-read-passphrase prompt)))
117 (defun smime-add-passphrase-cache (key passphrase)
118 (set (intern key smime-passphrase-cache)
120 (run-at-time smime-passphrase-cache-expiry nil
121 #'smime-remove-passphrase-cache
124 (defun smime-remove-passphrase-cache (key)
125 (let ((passphrase (symbol-value (intern-soft key smime-passphrase-cache))))
127 (fillarray passphrase ?_)
128 (unintern key smime-passphrase-cache))))
130 (defsubst smime-parse-attribute (string)
133 (if (string-match "=" attr)
134 (cons (intern (substring attr 0 (match-beginning 0)))
135 (substring attr (match-end 0)))
137 (split-string string "/"))))
139 (defsubst smime-query-signer (start end)
140 (smime-process-region start end smime-program (list "-qs"))
141 (with-current-buffer smime-output-buffer
142 (if (zerop (buffer-size)) nil
143 (goto-char (point-min))
144 (when (re-search-forward "^/" nil t)
145 (smime-parse-attribute
146 (buffer-substring (point) (progn (end-of-line)(point)))))
149 (defsubst smime-x509-hash (cert-file)
150 (with-current-buffer (get-buffer-create smime-output-buffer)
151 (buffer-disable-undo)
153 (apply #'call-process (car smime-x509-program) nil t nil
154 (append (cdr smime-x509-program)
155 (list "-hash" "-in" cert-file)))
156 (if (zerop (buffer-size)) nil
157 (buffer-substring (point-min) (1- (point-max))))))
159 (defsubst smime-x509-subject (cert-file)
160 (with-current-buffer (get-buffer-create smime-output-buffer)
161 (buffer-disable-undo)
163 (apply #'call-process (car smime-x509-program) nil t nil
164 (append (cdr smime-x509-program)
165 (list "-subject" "-in" cert-file)))
166 (if (zerop (buffer-size)) nil
167 (goto-char (point-min))
168 (when (re-search-forward "^subject=" nil t)
169 (smime-parse-attribute
170 (buffer-substring (point)(progn (end-of-line)(point))))))))
172 (defsubst smime-search-certificate (attr)
173 (let ((files (if (file-directory-p smime-certificate-directory)
174 (directory-files smime-certificate-directory)
178 (if (or (string-equal
179 (cdr (assq 'CN (smime-x509-subject (car files))))
180 (cdr (assq 'CN attr)))
182 (cdr (assq 'Email (smime-x509-subject (car files))))
183 (cdr (assq 'Email attr))))
184 (throw 'found (car files)))
187 (defun smime-process-region (start end program args)
188 (let* ((errors-file-name
189 (concat temporary-file-directory
190 (make-temp-name "smime-errors")))
191 (args (append args (list (concat "2>" errors-file-name))))
192 (shell-file-name smime-shell-file-name)
193 (shell-command-switch smime-shell-command-switch)
194 (process-connection-type nil)
195 process status exit-status)
196 (with-current-buffer (get-buffer-create smime-output-buffer)
197 (buffer-disable-undo)
201 (apply #'start-process-shell-command "*S/MIME*"
202 smime-output-buffer program args)))
203 (set-process-sentinel process 'ignore)
204 (process-send-region process start end)
205 (process-send-eof process)
206 (while (eq 'run (process-status process))
207 (accept-process-output process 5))
208 (setq status (process-status process)
209 exit-status (process-exit-status process))
210 (delete-process process)
211 (with-current-buffer smime-output-buffer
212 (goto-char (point-min))
213 (while (re-search-forward "\r$" (point-max) t)
216 (if (memq status '(stop signal))
217 (error "%s exited abnormally: '%s'" program exit-status))
218 (if (= 127 exit-status)
219 (error "%s could not be found" program))
221 (set-buffer (get-buffer-create smime-errors-buffer))
222 (buffer-disable-undo)
224 (insert-file-contents errors-file-name)
225 (delete-file errors-file-name)
227 (if (and process (eq 'run (process-status process)))
228 (interrupt-process process))
232 ;;; @ interface functions
236 (defun smime-encrypt-region (start end)
237 "Encrypt the current region between START and END."
239 (or smime-private-key-file
240 (expand-file-name (read-file-name "Public key file: "))))
241 (args (list "-e" key-file)))
242 (smime-process-region start end smime-program args)
243 (smime-process-when-success nil)))
246 (defun smime-decrypt-region (start end)
247 "Decrypt the current region between START and END."
249 (or smime-private-key-file
250 (expand-file-name (read-file-name "Private key file: "))))
251 (hash (smime-x509-hash key-file))
252 (passphrase (smime-read-passphrase
253 (format "S/MIME passphrase for %s: " hash)
255 (args (list "-d" key-file passphrase)))
256 (smime-process-region start end smime-program args)
257 (smime-process-when-success
258 (when smime-cache-passphrase
259 (smime-add-passphrase-cache hash passphrase)))))
262 (defun smime-sign-region (start end &optional cleartext)
263 "Make the signature from text between START and END.
264 If the optional 3rd argument CLEARTEXT is non-nil, it does not create
265 a detached signature."
267 (or smime-private-key-file
268 (expand-file-name (read-file-name "Private key file: "))))
269 (hash (smime-x509-hash key-file))
270 (passphrase (smime-read-passphrase
271 (format "S/MIME passphrase for %s: " hash)
273 (args (list "-ds" key-file passphrase)))
274 (smime-process-region start end smime-program args)
275 (smime-process-when-success
276 (when smime-cache-passphrase
277 (smime-add-passphrase-cache hash passphrase)))))
280 (defun smime-verify-region (start end signature)
281 "Verify the current region between START and END.
282 If the optional 3rd argument SIGNATURE is non-nil, it is treated as
283 the detached signature of the current region."
284 (let* ((basename (expand-file-name "smime" temporary-file-directory))
285 (orig-file (make-temp-name basename))
286 (args (list "-qs" signature))
287 (orig-mode (default-file-modes))
291 (set-default-file-modes 448)
292 (write-region-as-binary start end orig-file)
294 (set-default-file-modes orig-mode))
296 (insert-file-contents-as-binary signature)
297 (goto-char (point-max))
299 (insert-file-contents-as-binary
300 (or (smime-search-certificate
301 (smime-query-signer (point-min)(point-max)))
303 (read-file-name "Certificate file: "))))
304 (smime-process-region (point-min)(point-max) smime-program args))
305 (smime-process-when-success
306 (when smime-cache-passphrase
307 (smime-add-passphrase-cache hash passphrase)))
312 ;;; smime.el ends here