1 ;;; mml-smime.el --- S/MIME support for MML
3 ;; Copyright (C) 2000, 2001, 2002, 2003, 2004,
4 ;; 2005, 2006, 2007 Free Software Foundation, Inc.
6 ;; Author: Simon Josefsson <simon@josefsson.org>
7 ;; Keywords: Gnus, MIME, S/MIME, MML
9 ;; This file is part of GNU Emacs.
11 ;; GNU Emacs is free software; you can redistribute it and/or modify
12 ;; it under the terms of the GNU General Public License as published
13 ;; by the Free Software Foundation; either version 3, or (at your
14 ;; option) any later version.
16 ;; GNU Emacs 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., 51 Franklin Street, Fifth Floor,
24 ;; Boston, MA 02110-1301, USA.
30 (eval-when-compile (require 'cl))
35 (autoload 'message-narrow-to-headers "message")
36 (autoload 'message-fetch-field "message")
38 (defvar mml-smime-use 'openssl)
40 (defvar mml-smime-function-alist
41 '((openssl mml-smime-openssl-sign
42 mml-smime-openssl-encrypt
43 mml-smime-openssl-sign-query
44 mml-smime-openssl-encrypt-query
45 mml-smime-openssl-verify
46 mml-smime-openssl-verify-test)
47 (epg mml-smime-epg-sign
52 mml-smime-epg-verify-test)))
54 (defcustom mml-smime-verbose mml-secure-verbose
55 "If non-nil, ask the user about the current operation more verbosely."
59 (defcustom mml-smime-cache-passphrase mml-secure-cache-passphrase
60 "If t, cache passphrase."
64 (defcustom mml-smime-passphrase-cache-expiry mml-secure-passphrase-cache-expiry
65 "How many seconds the passphrase is cached.
66 Whether the passphrase is cached at all is controlled by
67 `mml-smime-cache-passphrase'."
71 (defcustom mml-smime-signers nil
72 "A list of your own key ID which will be used to sign a message."
74 :type '(repeat (string :tag "Key ID")))
76 (defun mml-smime-sign (cont)
77 (let ((func (nth 1 (assq mml-smime-use mml-smime-function-alist))))
80 (error "Cannot find sign function"))))
82 (defun mml-smime-encrypt (cont)
83 (let ((func (nth 2 (assq mml-smime-use mml-smime-function-alist))))
86 (error "Cannot find encrypt function"))))
88 (defun mml-smime-sign-query ()
89 (let ((func (nth 3 (assq mml-smime-use mml-smime-function-alist))))
93 (defun mml-smime-encrypt-query ()
94 (let ((func (nth 4 (assq mml-smime-use mml-smime-function-alist))))
98 (defun mml-smime-verify (handle ctl)
99 (let ((func (nth 5 (assq mml-smime-use mml-smime-function-alist))))
101 (funcall func handle ctl)
104 (defun mml-smime-verify-test (handle ctl)
105 (let ((func (nth 6 (assq mml-smime-use mml-smime-function-alist))))
107 (funcall func handle ctl))))
109 (defun mml-smime-openssl-sign (cont)
110 (when (null smime-keys)
111 (customize-variable 'smime-keys)
112 (error "No S/MIME keys configured, use customize to add your key"))
113 (smime-sign-buffer (cdr (assq 'keyfile cont)))
114 (goto-char (point-min))
115 (while (search-forward "\r\n" nil t)
116 (replace-match "\n" t t))
117 (goto-char (point-max)))
119 (defun mml-smime-openssl-encrypt (cont)
120 (let (certnames certfiles tmp file tmpfiles)
121 ;; xxx tmp files are always an security issue
122 (while (setq tmp (pop cont))
123 (if (and (consp tmp) (eq (car tmp) 'certfile))
124 (push (cdr tmp) certnames)))
125 (while (setq tmp (pop certnames))
126 (if (not (and (not (file-exists-p tmp))
129 (setq file (mm-make-temp-file (expand-file-name "mml."
131 (with-current-buffer tmp
132 (write-region (point-min) (point-max) file))
133 (push file certfiles)
134 (push file tmpfiles)))
135 (if (smime-encrypt-buffer certfiles)
137 (while (setq tmp (pop tmpfiles))
140 (while (setq tmp (pop tmpfiles))
143 (goto-char (point-max)))
145 (defvar gnus-extract-address-components)
147 (defun mml-smime-openssl-sign-query ()
148 ;; query information (what certificate) from user when MML tag is
149 ;; added, for use later by the signing process
150 (when (null smime-keys)
151 (customize-variable 'smime-keys)
152 (error "No S/MIME keys configured, use customize to add your key"))
154 (if (= (length smime-keys) 1)
156 (or (let ((from (cadr (funcall (if (boundp
157 'gnus-extract-address-components)
158 gnus-extract-address-components
159 'mail-extract-address-components)
162 (message-narrow-to-headers)
163 (message-fetch-field "from")))
165 (and from (smime-get-key-by-email from)))
166 (smime-get-key-by-email
167 (completing-read "Sign this part with what signature? "
169 (and (listp (car-safe smime-keys))
170 (caar smime-keys))))))))
172 (defun mml-smime-get-file-cert ()
174 (list 'certfile (read-file-name
175 "File with recipient's S/MIME certificate: "
176 smime-certificate-directory nil t ""))))
178 (defun mml-smime-get-dns-cert ()
179 ;; todo: deal with comma separated multiple recipients
180 (let (result who bad cert)
183 (setq who (read-from-minibuffer
184 (format "%sLookup certificate for: " (or bad ""))
185 (cadr (funcall (if (boundp
186 'gnus-extract-address-components)
187 gnus-extract-address-components
188 'mail-extract-address-components)
191 (message-narrow-to-headers)
192 (message-fetch-field "to")))
194 (if (setq cert (smime-cert-by-dns who))
195 (setq result (list 'certfile (buffer-name cert)))
196 (setq bad (format "`%s' not found. " who))))
200 (defun mml-smime-get-ldap-cert ()
201 ;; todo: deal with comma separated multiple recipients
202 (let (result who bad cert)
205 (setq who (read-from-minibuffer
206 (format "%sLookup certificate for: " (or bad ""))
207 (cadr (funcall gnus-extract-address-components
210 (message-narrow-to-headers)
211 (message-fetch-field "to")))
213 (if (setq cert (smime-cert-by-ldap who))
214 (setq result (list 'certfile (buffer-name cert)))
215 (setq bad (format "`%s' not found. " who))))
219 (defun mml-smime-openssl-encrypt-query ()
220 ;; todo: try dns/ldap automatically first, before prompting user
223 (ecase (read (gnus-completing-read-with-default
224 "ldap" "Fetch certificate from"
225 '(("dns") ("ldap") ("file")) nil t))
226 (dns (setq certs (append certs
227 (mml-smime-get-dns-cert))))
228 (ldap (setq certs (append certs
229 (mml-smime-get-ldap-cert))))
230 (file (setq certs (append certs
231 (mml-smime-get-file-cert)))))
232 (setq done (not (y-or-n-p "Add more recipients? "))))
235 (defun mml-smime-openssl-verify (handle ctl)
237 (insert-buffer-substring (mm-handle-multipart-original-buffer ctl))
238 (goto-char (point-min))
239 (insert (format "Content-Type: %s; " (mm-handle-media-type ctl)))
240 (insert (format "protocol=\"%s\"; "
241 (mm-handle-multipart-ctl-parameter ctl 'protocol)))
242 (insert (format "micalg=\"%s\"; "
243 (mm-handle-multipart-ctl-parameter ctl 'micalg)))
244 (insert (format "boundary=\"%s\"\n\n"
245 (mm-handle-multipart-ctl-parameter ctl 'boundary)))
246 (when (get-buffer smime-details-buffer)
247 (kill-buffer smime-details-buffer))
248 (let ((buf (current-buffer))
249 (good-signature (smime-noverify-buffer))
250 (good-certificate (and (or smime-CA-file smime-CA-directory)
251 (smime-verify-buffer)))
252 addresses openssl-output)
253 (setq openssl-output (with-current-buffer smime-details-buffer
255 (if (not good-signature)
257 ;; we couldn't verify message, fail with openssl output as message
258 (mm-set-handle-multipart-parameter
259 mm-security-handle 'gnus-info "Failed")
260 (mm-set-handle-multipart-parameter
261 mm-security-handle 'gnus-details
262 (concat "OpenSSL failed to verify message integrity:\n"
263 "-------------------------------------------\n"
265 ;; verify mail addresses in mail against those in certificate
266 (when (and (smime-pkcs7-region (point-min) (point-max))
267 (smime-pkcs7-certificates-region (point-min) (point-max)))
269 (insert-buffer-substring buf)
270 (goto-char (point-min))
271 (while (re-search-forward "-----END CERTIFICATE-----" nil t)
272 (when (smime-pkcs7-email-region (point-min) (point))
273 (setq addresses (append (smime-buffer-as-string-region
274 (point-min) (point)) addresses)))
275 (delete-region (point-min) (point)))
276 (setq addresses (mapcar 'downcase addresses))))
277 (if (not (member (downcase (or (mm-handle-multipart-from ctl) "")) addresses))
278 (mm-set-handle-multipart-parameter
279 mm-security-handle 'gnus-info "Sender address forged")
281 (mm-set-handle-multipart-parameter
282 mm-security-handle 'gnus-info "Ok (sender authenticated)")
283 (mm-set-handle-multipart-parameter
284 mm-security-handle 'gnus-info "Ok (sender not trusted)")))
285 (mm-set-handle-multipart-parameter
286 mm-security-handle 'gnus-details
287 (concat "Sender claimed to be: " (mm-handle-multipart-from ctl) "\n"
289 (concat "Addresses in certificate: "
290 (mapconcat 'identity addresses ", "))
291 "No addresses found in certificate. (Requires OpenSSL 0.9.6 or later.)")
294 "---------------\n" openssl-output "\n"
295 "Certificate(s) inside S/MIME signature:\n"
296 "---------------------------------------\n"
297 (buffer-string) "\n")))))
300 (defun mml-smime-openssl-verify-test (handle ctl)
301 smime-openssl-program)
303 (defvar epg-user-id-alist)
304 (defvar epg-digest-algorithm-alist)
305 (defvar inhibit-redisplay)
306 (defvar password-cache-expiry)
309 (autoload 'epg-make-context "epg")
310 (autoload 'epg-context-set-armor "epg")
311 (autoload 'epg-context-set-signers "epg")
312 (autoload 'epg-context-result-for "epg")
313 (autoload 'epg-new-signature-digest-algorithm "epg")
314 (autoload 'epg-verify-result-to-string "epg")
315 (autoload 'epg-list-keys "epg")
316 (autoload 'epg-decrypt-string "epg")
317 (autoload 'epg-verify-string "epg")
318 (autoload 'epg-sign-string "epg")
319 (autoload 'epg-encrypt-string "epg")
320 (autoload 'epg-passphrase-callback-function "epg")
321 (autoload 'epg-context-set-passphrase-callback "epg")
322 (autoload 'epg-configuration "epg-config")
323 (autoload 'epg-expand-group "epg-config")
324 (autoload 'epa-select-keys "epa"))
326 (defvar mml-smime-epg-secret-key-id-list nil)
328 (defun mml-smime-epg-passphrase-callback (context key-id ignore)
330 (epg-passphrase-callback-function context key-id nil)
335 "Passphrase for PIN: "
336 (if (setq entry (assoc key-id epg-user-id-alist))
337 (format "Passphrase for %s %s: " key-id (cdr entry))
338 (format "Passphrase for %s: " key-id)))
343 (let ((password-cache-expiry mml-smime-passphrase-cache-expiry))
344 (password-cache-add key-id passphrase))
345 (setq mml-smime-epg-secret-key-id-list
346 (cons key-id mml-smime-epg-secret-key-id-list))
347 (copy-sequence passphrase)))))
349 (defun mml-smime-epg-find-usable-key (keys usage)
352 (let ((pointer (epg-key-sub-key-list (car keys))))
354 (if (and (memq usage (epg-sub-key-capability (car pointer)))
355 (not (memq (epg-sub-key-validity (car pointer))
356 '(revoked expired))))
357 (throw 'found (car keys)))
358 (setq pointer (cdr pointer))))
359 (setq keys (cdr keys)))))
361 (defun mml-smime-epg-sign (cont)
362 (let* ((inhibit-redisplay t)
363 (context (epg-make-context 'CMS))
364 (boundary (mml-compute-boundary cont))
367 (or (message-options-get 'mml-smime-epg-signers)
369 'mml-smime-epg-signers
370 (if mml-smime-verbose
371 (epa-select-keys context "\
372 Select keys for signing.
373 If no one is selected, default secret key is used. "
375 (if mml-smime-signers
378 (setq signer-key (mml-smime-epg-find-usable-key
379 (epg-list-keys context signer t)
381 (unless (or signer-key
383 (format "No secret key for %s; skip it? "
385 (error "No secret key for %s" signer))
387 mml-smime-signers))))))
389 (epg-context-set-signers context signers)
390 (if mml-smime-cache-passphrase
391 (epg-context-set-passphrase-callback
393 #'mml-smime-epg-passphrase-callback))
394 (condition-case error
395 (setq signature (epg-sign-string context
396 (mm-replace-in-string (buffer-string)
399 mml-smime-epg-secret-key-id-list nil)
401 (while mml-smime-epg-secret-key-id-list
402 (password-cache-remove (car mml-smime-epg-secret-key-id-list))
403 (setq mml-smime-epg-secret-key-id-list
404 (cdr mml-smime-epg-secret-key-id-list)))
405 (signal (car error) (cdr error))))
406 (if (epg-context-result-for context 'sign)
407 (setq micalg (epg-new-signature-digest-algorithm
408 (car (epg-context-result-for context 'sign)))))
409 (goto-char (point-min))
410 (insert (format "Content-Type: multipart/signed; boundary=\"%s\";\n"
413 (insert (format "\tmicalg=%s; "
416 epg-digest-algorithm-alist))))))
417 (insert "protocol=\"application/pkcs7-signature\"\n")
418 (insert (format "\n--%s\n" boundary))
419 (goto-char (point-max))
420 (insert (format "\n--%s\n" boundary))
421 (insert "Content-Type: application/pkcs7-signature; name=smime.p7s
422 Content-Transfer-Encoding: base64
423 Content-Disposition: attachment; filename=smime.p7s
426 (insert (base64-encode-string signature) "\n")
427 (goto-char (point-max))
428 (insert (format "--%s--\n" boundary))
429 (goto-char (point-max))))
431 (defun mml-smime-epg-encrypt (cont)
432 (let ((inhibit-redisplay t)
433 (context (epg-make-context 'CMS))
434 (config (epg-configuration))
435 (recipients (message-options-get 'mml-smime-epg-recipients))
437 (boundary (mml-compute-boundary cont))
444 (or (epg-expand-group config recipient)
447 (or (message-options-get 'message-recipients)
448 (message-options-set 'message-recipients
449 (read-string "Recipients: ")))
450 "[ \f\t\n\r\v,]+"))))
451 (if mml-smime-verbose
453 (epa-select-keys context "\
454 Select recipients for encryption.
455 If no one is selected, symmetric encryption will be performed. "
460 (setq recipient-key (mml-smime-epg-find-usable-key
461 (epg-list-keys context recipient)
463 (unless (or recipient-key
465 (format "No public key for %s; skip it? "
467 (error "No public key for %s" recipient))
471 (error "No recipient specified")))
472 (message-options-set 'mml-smime-epg-recipients recipients))
473 (if mml-smime-cache-passphrase
474 (epg-context-set-passphrase-callback
476 #'mml-smime-epg-passphrase-callback))
477 (condition-case error
479 (epg-encrypt-string context (buffer-string) recipients)
480 mml-smime-epg-secret-key-id-list nil)
482 (while mml-smime-epg-secret-key-id-list
483 (password-cache-remove (car mml-smime-epg-secret-key-id-list))
484 (setq mml-smime-epg-secret-key-id-list
485 (cdr mml-smime-epg-secret-key-id-list)))
486 (signal (car error) (cdr error))))
487 (delete-region (point-min) (point-max))
488 (goto-char (point-min))
490 Content-Type: application/pkcs7-mime;
491 smime-type=enveloped-data;
493 Content-Transfer-Encoding: base64
494 Content-Disposition: attachment; filename=smime.p7m
497 (insert (base64-encode-string cipher))
498 (goto-char (point-max))))
500 (defun mml-smime-epg-verify (handle ctl)
502 (let ((inhibit-redisplay t)
503 context plain signature-file part signature)
504 (when (or (null (setq part (mm-find-raw-part-by-type
505 ctl (or (mm-handle-multipart-ctl-parameter
507 "application/pkcs7-signature")
509 (null (setq signature (mm-find-part-by-type
511 "application/pkcs7-signature"
513 (mm-set-handle-multipart-parameter
514 mm-security-handle 'gnus-info "Corrupted")
515 (throw 'error handle))
516 (setq part (mm-replace-in-string part "\n" "\r\n" t)
517 context (epg-make-context 'CMS))
518 (condition-case error
519 (setq plain (epg-verify-string context (mm-get-part signature) part))
521 (mm-set-handle-multipart-parameter
522 mm-security-handle 'gnus-info "Failed")
523 (if (eq (car error) 'quit)
524 (mm-set-handle-multipart-parameter
525 mm-security-handle 'gnus-details "Quit.")
526 (mm-set-handle-multipart-parameter
527 mm-security-handle 'gnus-details (format "%S" error)))
528 (throw 'error handle)))
529 (mm-set-handle-multipart-parameter
530 mm-security-handle 'gnus-info
531 (epg-verify-result-to-string (epg-context-result-for context 'verify)))
534 (defun mml-smime-epg-verify-test (handle ctl)
539 ;;; arch-tag: f1bf94d4-f2cd-4c6f-b059-ad69492817e2
540 ;;; mml-smime.el ends here