--- /dev/null
+;;; smime-card.el --- Make smime.el work with card readers
+
+;; Copyright (C) 2005 Brailcom, o.p.s.
+;; Author: Milan Zamazal <pdm@zamazal.org>
+
+;; COPYRIGHT NOTICE
+;;
+;; This program is free software; you can redistribute it and/or modify it
+;; under the terms of the GNU General Public License as published by the Free
+;; Software Foundation; either version 2, or (at your option) any later
+;; version.
+;;
+;; This program is distributed in the hope that it will be useful, but
+;; WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+;; or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+;; for more details.
+;;
+;; You should have received a copy of the GNU General Public License
+;; along with this program; if not, see <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; This is a simple wrapper around smime.el allowing to use private keys stored
+;; on a smard card.
+;;
+;; To use it, just put (require 'smime-card) to you Emacs startup file and
+;; customize the variable `smime-card-file-keys'.
+
+;;; Code:
+
+(require 'smime)
+
+;;; Configuration
+
+(defcustom smime-card-file-keys '()
+ "Alist of certificate files and their corresponding private key card ids.
+Each element of the list is of the form (FILE . KEY-ID), where FILE is a
+certificate file stored on a regular file system and KEY-ID is the identifier
+of the corresponding private key stored on the card.
+If FILE begins with the prefix `card:', the certificate is retrieved from the
+card under the id following the `card:' prefix in FILE."
+ :type '(alist :key-type (file :tag "Certificate file")
+ :value-type (string :tag "Key identifier"))
+ :group 'smime)
+
+(defcustom smime-card-fetch-certificates nil
+ "If non-nil, fetch certificates from the card before verifying messages."
+ :type 'boolean
+ :group 'smime)
+
+;;; Internals
+
+(defvar smime-card-key nil)
+
+(defun smime-card-key (keyfile)
+ (cdr (assoc keyfile smime-card-file-keys)))
+
+(defvar smime-card-engine-command
+ "engine dynamic -pre SO_PATH:/usr/lib/opensc/engine_pkcs11.so -pre ID:pkcs11 -pre LIST_ADD:1 -pre LOAD\n")
+
+(defvar smime-card-process-output "")
+
+(defun smime-card-process-filter (process string)
+ (setq smime-card-process-output (concat smime-card-process-output string)))
+
+(defun smime-card-wait-for-prompt (process)
+ (while (not (string-match "\\(OpenSSL> \\|PIN: \\)$"
+ smime-card-process-output))
+ (unless (accept-process-output process 5)
+ (message "OpenSSL: Timeout")
+ (throw 'error nil)))
+ (prog1 (if (string= (match-string 1 smime-card-process-output) "PIN: ")
+ 'pin
+ t)
+ (setq smime-card-process-output "")))
+
+(defun smime-card-call-openssl-region (b e buf &rest args)
+ (let* ((infile (make-temp-file "smime-card-in"))
+ (outfile (make-temp-file "smime-card-out"))
+ (cert-on-card (and (string-match "^card:\\(.*\\)$" keyfile)
+ (match-string 1 keyfile)))
+ (certfile (and cert-on-card (make-temp-file "smime-card-cert")))
+ (args (append args
+ (list "-engine" "pkcs11"
+ "-keyform" "engine"
+ "-inkey" smime-card-key
+ "-in" infile "-out" outfile)))
+ (process (start-process "openssl" " *openssl*" smime-openssl-program)))
+ (unwind-protect
+ (catch 'error
+ (when certfile
+ (unless (= (call-process "pkcs15-tool" nil nil nil
+ "-r" cert-on-card "-o" certfile)
+ 0)
+ (message "pkcs15: Error")
+ (throw 'error nil))
+ (let ((args* args))
+ (while (and args* (not (string= (car args*) "-signer")))
+ (setq args* (cdr args*)))
+ (setq args* (cdr args*))
+ (when args*
+ (setcar args* certfile))))
+ (setq smime-card-process-output "")
+ (set-process-filter process 'smime-card-process-filter)
+ (unless (eq (smime-card-wait-for-prompt process) t)
+ (message "OpenSSL: Error on startup")
+ (throw 'error nil))
+ (process-send-string process smime-card-engine-command)
+ (unless (eq (smime-card-wait-for-prompt process) t)
+ (message "OpenSSL: Error in pkcs11 loading")
+ (throw 'error nil))
+ (write-region b e infile nil 0)
+ (process-send-string process
+ (concat (mapconcat 'identity args " ") "\n"))
+ (let ((answer (smime-card-wait-for-prompt process)))
+ (cond
+ ((eq answer 'pin)
+ (process-send-string process (concat (read-passwd "Smartcard PIN: ") "\n"))
+ (unless (eq (smime-card-wait-for-prompt process) t)
+ (message "OpenSSL: Error after passphrase")
+ (throw 'error nil)))
+ ((eq answer t)
+ nil)
+ (t
+ (message "OpenSSL: Error in processing")
+ (throw 'error nil))))
+ (process-send-eof process)
+ (with-current-buffer (car buf)
+ (when (= (cadr (insert-file-contents outfile)) 0)
+ (message "OpenSSL: Empty output")
+ (throw 'error nil)))
+ t)
+ (delete-file infile)
+ (delete-file outfile)
+ (when certfile (delete-file certfile))
+ (delete-process process)
+ (kill-buffer " *openssl*"))))
+
+;;; smime.el advices
+
+(defadvice smime-sign-region (around smime-card-sign-region activate)
+ (let ((smime-card-key (smime-card-key (ad-get-arg 2))))
+ ad-do-it))
+
+(defadvice smime-decrypt-region (around smime-card-decrypt-region activate)
+ (let ((smime-card-key (smime-card-key (ad-get-arg 2))))
+ ad-do-it))
+
+(defadvice smime-call-openssl-region (around smime-card-openssl activate)
+ (if smime-card-key
+ (setq ad-return-value
+ (apply 'smime-card-call-openssl-region (ad-get-args 0)))
+ ad-do-it))
+
+(defadvice smime-verify-region (around smime-card-verify-region activate)
+ (if smime-card-fetch-certificates
+ (let ((cert-ids '()))
+ (with-temp-buffer
+ (unless (= (call-process
+ "pkcs15-tool" nil t nil "--list-certificates")
+ 0)
+ (error "pkcs15: Certificate listing"))
+ (goto-char (point-min))
+ (while (re-search-forward "^[\t ]+ID[ ]+: \\([0-9]+\\) *$" nil t)
+ (setq cert-ids (cons (match-string 1) cert-ids))))
+ (let ((certfile (make-temp-file "smime-card")))
+ (unwind-protect
+ (progn
+ (with-temp-file certfile
+ (when smime-CA-file
+ (insert-file-contents smime-CA-file))
+ (mapc (lambda (id)
+ (unless (= (call-process "pkcs15-tool" nil t nil
+ "-r" id)
+ 0)
+ (error "pkcs15: Certificat read")))
+ cert-ids))
+ (let ((smime-CA-file certfile))
+ ad-do-it))
+ (delete-file certfile))))
+ ad-do-it))
+
+(defadvice mml-smime-verify (around smime-card-mml-smime-verify activate)
+ ;; If both smime-CA-directory and smime-CA-file are unset, `mml-smime-verify'
+ ;; refuses to perform certificate verification.
+ (let ((smime-CA-file (if smime-card-fetch-certificates
+ (or smime-CA-file "/dev/null")
+ smime-CA-file)))
+ ad-do-it))
+
+;;; Announce
+
+(provide 'smime-card)
+
+;;; smime-card.el ends here
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