lisp/gnus/mml-smime.el

   1 ;;; mml-smime.el --- S/MIME support for MML
   2
   3 ;; Copyright (C) 2000, 2001, 2002, 2003, 2004,
   4 ;;   2005, 2006 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