1;;; mml-smime.el --- S/MIME support for MML
2
3;; Copyright (C) 2000, 2001, 2002, 2003, 2004,
4;;   2005, 2006, 2007 Free Software Foundation, Inc.
5
6;; Author: Simon Josefsson <simon@josefsson.org>
7;; Keywords: Gnus, MIME, S/MIME, MML
8
9;; This file is part of GNU Emacs.
10
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 2, or (at your
14;; option) any later version.
15
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.
20
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.
25
26;;; Commentary:
27
28;;; Code:
29
30(eval-when-compile (require 'cl))
31
32(require 'smime)
33(require 'mm-decode)
34(autoload 'message-narrow-to-headers "message")
35(autoload 'message-fetch-field "message")
36
37(defun mml-smime-sign (cont)
38  (when (null smime-keys)
39    (customize-variable 'smime-keys)
40    (error "No S/MIME keys configured, use customize to add your key"))
41  (smime-sign-buffer (cdr (assq 'keyfile cont)))
42  (goto-char (point-min))
43  (while (search-forward "\r\n" nil t)
44    (replace-match "\n" t t))
45  (goto-char (point-max)))
46
47(defun mml-smime-encrypt (cont)
48  (let (certnames certfiles tmp file tmpfiles)
49    ;; xxx tmp files are always an security issue
50    (while (setq tmp (pop cont))
51      (if (and (consp tmp) (eq (car tmp) 'certfile))
52	  (push (cdr tmp) certnames)))
53    (while (setq tmp (pop certnames))
54      (if (not (and (not (file-exists-p tmp))
55		    (get-buffer tmp)))
56	  (push tmp certfiles)
57	(setq file (mm-make-temp-file (expand-file-name "mml."
58							mm-tmp-directory)))
59	(with-current-buffer tmp
60	  (write-region (point-min) (point-max) file))
61	(push file certfiles)
62	(push file tmpfiles)))
63    (if (smime-encrypt-buffer certfiles)
64	(progn
65	  (while (setq tmp (pop tmpfiles))
66	    (delete-file tmp))
67	  t)
68      (while (setq tmp (pop tmpfiles))
69	(delete-file tmp))
70      nil))
71  (goto-char (point-max)))
72
73(defun mml-smime-sign-query ()
74  ;; query information (what certificate) from user when MML tag is
75  ;; added, for use later by the signing process
76  (when (null smime-keys)
77    (customize-variable 'smime-keys)
78    (error "No S/MIME keys configured, use customize to add your key"))
79  (list 'keyfile
80	(if (= (length smime-keys) 1)
81	    (cadar smime-keys)
82	  (or (let ((from (cadr (funcall (if (boundp
83					      'gnus-extract-address-components)
84					     gnus-extract-address-components
85					   'mail-extract-address-components)
86					 (or (save-excursion
87					       (save-restriction
88						 (message-narrow-to-headers)
89						 (message-fetch-field "from")))
90					     "")))))
91		(and from (smime-get-key-by-email from)))
92	      (smime-get-key-by-email
93	       (completing-read "Sign this part with what signature? "
94				smime-keys nil nil
95				(and (listp (car-safe smime-keys))
96				     (caar smime-keys))))))))
97
98(defun mml-smime-get-file-cert ()
99  (ignore-errors
100    (list 'certfile (read-file-name
101		     "File with recipient's S/MIME certificate: "
102		     smime-certificate-directory nil t ""))))
103
104(defun mml-smime-get-dns-cert ()
105  ;; todo: deal with comma separated multiple recipients
106  (let (result who bad cert)
107    (condition-case ()
108	(while (not result)
109	  (setq who (read-from-minibuffer
110		     (format "%sLookup certificate for: " (or bad ""))
111		     (cadr (funcall (if (boundp
112					 'gnus-extract-address-components)
113					gnus-extract-address-components
114				      'mail-extract-address-components)
115				    (or (save-excursion
116					  (save-restriction
117					    (message-narrow-to-headers)
118					    (message-fetch-field "to")))
119					"")))))
120	  (if (setq cert (smime-cert-by-dns who))
121	      (setq result (list 'certfile (buffer-name cert)))
122	    (setq bad (format "`%s' not found. " who))))
123      (quit))
124    result))
125
126(defun mml-smime-encrypt-query ()
127  ;; todo: add ldap support (xemacs ldap api?)
128  ;; todo: try dns/ldap automatically first, before prompting user
129  (let (certs done)
130    (while (not done)
131      (ecase (read (gnus-completing-read-with-default
132		    "dns" "Fetch certificate from"
133		    '(("dns") ("file")) nil t))
134	(dns (setq certs (append certs
135				 (mml-smime-get-dns-cert))))
136	(file (setq certs (append certs
137				  (mml-smime-get-file-cert)))))
138      (setq done (not (y-or-n-p "Add more recipients? "))))
139    certs))
140
141(defun mml-smime-verify (handle ctl)
142  (with-temp-buffer
143    (insert-buffer-substring (mm-handle-multipart-original-buffer ctl))
144    (goto-char (point-min))
145    (insert (format "Content-Type: %s; " (mm-handle-media-type ctl)))
146    (insert (format "protocol=\"%s\"; "
147		    (mm-handle-multipart-ctl-parameter ctl 'protocol)))
148    (insert (format "micalg=\"%s\"; "
149		    (mm-handle-multipart-ctl-parameter ctl 'micalg)))
150    (insert (format "boundary=\"%s\"\n\n"
151		    (mm-handle-multipart-ctl-parameter ctl 'boundary)))
152    (when (get-buffer smime-details-buffer)
153      (kill-buffer smime-details-buffer))
154    (let ((buf (current-buffer))
155	  (good-signature (smime-noverify-buffer))
156	  (good-certificate (and (or smime-CA-file smime-CA-directory)
157				 (smime-verify-buffer)))
158	  addresses openssl-output)
159      (setq openssl-output (with-current-buffer smime-details-buffer
160			     (buffer-string)))
161      (if (not good-signature)
162	  (progn
163	    ;; we couldn't verify message, fail with openssl output as message
164	    (mm-set-handle-multipart-parameter
165	     mm-security-handle 'gnus-info "Failed")
166	    (mm-set-handle-multipart-parameter
167	     mm-security-handle 'gnus-details
168	     (concat "OpenSSL failed to verify message integrity:\n"
169		     "-------------------------------------------\n"
170		     openssl-output)))
171	;; verify mail addresses in mail against those in certificate
172	(when (and (smime-pkcs7-region (point-min) (point-max))
173		   (smime-pkcs7-certificates-region (point-min) (point-max)))
174	  (with-temp-buffer
175	    (insert-buffer-substring buf)
176	    (goto-char (point-min))
177	    (while (re-search-forward "-----END CERTIFICATE-----" nil t)
178	      (when (smime-pkcs7-email-region (point-min) (point))
179		(setq addresses (append (smime-buffer-as-string-region
180					 (point-min) (point)) addresses)))
181	      (delete-region (point-min) (point)))
182	    (setq addresses (mapcar 'downcase addresses))))
183	(if (not (member (downcase (or (mm-handle-multipart-from ctl) "")) addresses))
184	    (mm-set-handle-multipart-parameter
185	     mm-security-handle 'gnus-info "Sender address forged")
186	  (if good-certificate
187	      (mm-set-handle-multipart-parameter
188	       mm-security-handle 'gnus-info "Ok (sender authenticated)")
189	    (mm-set-handle-multipart-parameter
190	     mm-security-handle 'gnus-info "Ok (sender not trusted)")))
191	(mm-set-handle-multipart-parameter
192	 mm-security-handle 'gnus-details
193	 (concat "Sender claimed to be: " (mm-handle-multipart-from ctl) "\n"
194		 (if addresses
195		     (concat "Addresses in certificate: "
196			     (mapconcat 'identity addresses ", "))
197		   "No addresses found in certificate. (Requires OpenSSL 0.9.6 or later.)")
198		 "\n" "\n"
199		 "OpenSSL output:\n"
200		 "---------------\n" openssl-output "\n"
201		 "Certificate(s) inside S/MIME signature:\n"
202		 "---------------------------------------\n"
203		 (buffer-string) "\n")))))
204  handle)
205
206(defun mml-smime-verify-test (handle ctl)
207  smime-openssl-program)
208
209(provide 'mml-smime)
210
211;;; arch-tag: f1bf94d4-f2cd-4c6f-b059-ad69492817e2
212;;; mml-smime.el ends here
213