lisp/gnus/mml1991.el

   1 ;;; mml1991.el --- Old PGP message format (RFC 1991) support for MML
   2
   3 ;; Copyright (C) 1998-2015 Free Software Foundation, Inc.
   4
   5 ;; Author: Sascha Lüdecke <sascha@meta-x.de>,
   6 ;;      Simon Josefsson <simon@josefsson.org> (Mailcrypt interface, Gnus glue)
   7 ;; Keywords: PGP
   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 by
  13 ;; the Free Software Foundation, either version 3 of the License, or
  14 ;; (at your option) any later version.
  15
  16 ;; GNU Emacs is distributed in the hope that it will be useful,
  17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 ;; GNU 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.  If not, see <http://www.gnu.org/licenses/>.
  23
  24 ;;; Commentary:
  25
  26 ;;; Code:
  27
  28 (eval-and-compile
  29   (if (locate-library "password-cache")
  30       (require 'password-cache)
  31     (require 'password)))
  32
  33 (eval-when-compile
  34   (require 'cl)
  35   (require 'mm-util))
  36
  37 (require 'mm-encode)
  38 (require 'mml-sec)
  39
  40 (defvar mc-pgp-always-sign)
  41
  42 (autoload 'quoted-printable-decode-region "qp")
  43 (autoload 'quoted-printable-encode-region "qp")
  44
  45 (autoload 'mm-decode-content-transfer-encoding "mm-bodies")
  46 (autoload 'mm-encode-content-transfer-encoding "mm-bodies")
  47 (autoload 'message-options-get "message")
  48 (autoload 'message-options-set "message")
  49
  50 (require 'mml2015)
  51
  52 (defvar mml1991-use mml2015-use
  53   "The package used for PGP.")
  54
  55 (defvar mml1991-function-alist
  56   '((mailcrypt mml1991-mailcrypt-sign
  57                mml1991-mailcrypt-encrypt)
  58     (pgg mml1991-pgg-sign
  59          mml1991-pgg-encrypt)
  60     (epg mml1991-epg-sign
  61          mml1991-epg-encrypt))
  62   "Alist of PGP functions.")
  63
  64 (defvar mml1991-cache-passphrase mml-secure-cache-passphrase
  65   "If t, cache passphrase.")
  66
  67 (defvar mml1991-passphrase-cache-expiry mml-secure-passphrase-cache-expiry
  68   "How many seconds the passphrase is cached.
  69 Whether the passphrase is cached at all is controlled by
  70 `mml1991-cache-passphrase'.")
  71
  72 (defvar mml1991-signers nil
  73   "A list of your own key ID which will be used to sign a message.")
  74
  75 (defvar mml1991-encrypt-to-self nil
  76   "If t, add your own key ID to recipient list when encryption.")
  77
  78 ;;; mailcrypt wrapper
  79
  80 (autoload 'mc-sign-generic "mc-toplev")
  81
  82 (defvar mml1991-decrypt-function 'mailcrypt-decrypt)
  83 (defvar mml1991-verify-function 'mailcrypt-verify)
  84
  85 (defun mml1991-mailcrypt-sign (cont)
  86   (let ((text (current-buffer))
  87         headers signature
  88         (result-buffer (get-buffer-create "*GPG Result*")))
  89     ;; Save MIME Content[^ ]+: headers from signing
  90     (goto-char (point-min))
  91     (while (looking-at "^Content[^ ]+:") (forward-line))
  92     (unless (bobp)
  93       (setq headers (buffer-string))
  94       (delete-region (point-min) (point)))
  95     (goto-char (point-max))
  96     (unless (bolp)
  97       (insert "\n"))
  98     (quoted-printable-decode-region (point-min) (point-max))
  99     (with-temp-buffer
 100       (setq signature (current-buffer))
 101       (insert-buffer-substring text)
 102       (unless (mc-sign-generic (message-options-get 'message-sender)
 103                                nil nil nil nil)
 104         (unless (> (point-max) (point-min))
 105           (pop-to-buffer result-buffer)
 106           (error "Sign error")))
 107       (goto-char (point-min))
 108       (while (re-search-forward "\r+$" nil t)
 109         (replace-match "" t t))
 110       (quoted-printable-encode-region (point-min) (point-max))
 111       (set-buffer text)
 112       (delete-region (point-min) (point-max))
 113       (if headers (insert headers))
 114       (insert "\n")
 115       (insert-buffer-substring signature)
 116       (goto-char (point-max)))))
 117
 118 (declare-function mc-encrypt-generic "ext:mc-toplev"
 119                   (&optional recipients scheme start end from sign))
 120
 121 (defun mml1991-mailcrypt-encrypt (cont &optional sign)
 122   (let ((text (current-buffer))
 123         (mc-pgp-always-sign
 124          (or mc-pgp-always-sign
 125              sign
 126              (eq t (or (message-options-get 'message-sign-encrypt)
 127                        (message-options-set
 128                         'message-sign-encrypt
 129                         (or (y-or-n-p "Sign the message? ")
 130                             'not))))
 131              'never))
 132         cipher
 133         (result-buffer (get-buffer-create "*GPG Result*")))
 134     ;; Strip MIME Content[^ ]: headers since it will be ASCII ARMORED
 135     (goto-char (point-min))
 136     (while (looking-at "^Content[^ ]+:") (forward-line))
 137     (unless (bobp)
 138       (delete-region (point-min) (point)))
 139     (with-temp-buffer
 140       (inline (mm-disable-multibyte))
 141       (setq cipher (current-buffer))
 142       (insert-buffer-substring text)
 143       (unless (mc-encrypt-generic
 144                (or
 145                 (message-options-get 'message-recipients)
 146                 (message-options-set 'message-recipients
 147                                      (read-string "Recipients: ")))
 148                nil
 149                (point-min) (point-max)
 150                (message-options-get 'message-sender)
 151                'sign)
 152         (unless (> (point-max) (point-min))
 153           (pop-to-buffer result-buffer)
 154           (error "Encrypt error")))
 155       (goto-char (point-min))
 156       (while (re-search-forward "\r+$" nil t)
 157         (replace-match "" t t))
 158       (set-buffer text)
 159       (delete-region (point-min) (point-max))
 160       ;;(insert "Content-Type: application/pgp-encrypted\n\n")
 161       ;;(insert "Version: 1\n\n")
 162       (insert "\n")
 163       (insert-buffer-substring cipher)
 164       (goto-char (point-max)))))
 165
 166 ;; pgg wrapper
 167
 168 (autoload 'pgg-sign-region "pgg")
 169 (autoload 'pgg-encrypt-region "pgg")
 170
 171 (defvar pgg-default-user-id)
 172 (defvar pgg-errors-buffer)
 173 (defvar pgg-output-buffer)
 174
 175 (defun mml1991-pgg-sign (cont)
 176   (let ((pgg-text-mode t)
 177         (pgg-default-user-id (or (message-options-get 'mml-sender)
 178                                  pgg-default-user-id))
 179         headers cte)
 180     ;; Don't sign headers.
 181     (goto-char (point-min))
 182     (when (re-search-forward "^$" nil t)
 183       (setq headers (buffer-substring (point-min) (point)))
 184       (save-restriction
 185         (narrow-to-region (point-min) (point))
 186         (setq cte (mail-fetch-field "content-transfer-encoding")))
 187       (forward-line 1)
 188       (delete-region (point-min) (point))
 189       (when cte
 190         (setq cte (intern (downcase cte)))
 191         (mm-decode-content-transfer-encoding cte)))
 192     (unless (pgg-sign-region (point-min) (point-max) t)
 193       (pop-to-buffer pgg-errors-buffer)
 194       (error "Encrypt error"))
 195     (delete-region (point-min) (point-max))
 196     (mm-with-unibyte-current-buffer
 197       (insert-buffer-substring pgg-output-buffer)
 198       (goto-char (point-min))
 199       (while (re-search-forward "\r+$" nil t)
 200         (replace-match "" t t))
 201       (when cte
 202         (mm-encode-content-transfer-encoding cte))
 203       (goto-char (point-min))
 204       (when headers
 205         (insert headers))
 206       (insert "\n"))
 207     t))
 208
 209 (defun mml1991-pgg-encrypt (cont &optional sign)
 210   (goto-char (point-min))
 211   (when (re-search-forward "^$" nil t)
 212     (let ((cte (save-restriction
 213                  (narrow-to-region (point-min) (point))
 214                  (mail-fetch-field "content-transfer-encoding"))))
 215       ;; Strip MIME headers since it will be ASCII armored.
 216       (forward-line 1)
 217       (delete-region (point-min) (point))
 218       (when cte
 219         (mm-decode-content-transfer-encoding (intern (downcase cte))))))
 220   (unless (let ((pgg-text-mode t))
 221             (pgg-encrypt-region
 222              (point-min) (point-max)
 223              (split-string
 224               (or
 225                (message-options-get 'message-recipients)
 226                (message-options-set 'message-recipients
 227                                     (read-string "Recipients: ")))
 228               "[ \f\t\n\r\v,]+")
 229              sign))
 230     (pop-to-buffer pgg-errors-buffer)
 231     (error "Encrypt error"))
 232   (delete-region (point-min) (point-max))
 233   (insert "\n")
 234   (insert-buffer-substring pgg-output-buffer)
 235   t)
 236
 237 ;; epg wrapper
 238
 239 (defvar epg-user-id-alist)
 240
 241 (autoload 'epg-make-context "epg")
 242 (autoload 'epg-passphrase-callback-function "epg")
 243 (autoload 'epa-select-keys "epa")
 244 (autoload 'epg-list-keys "epg")
 245 (autoload 'epg-context-set-armor "epg")
 246 (autoload 'epg-context-set-textmode "epg")
 247 (autoload 'epg-context-set-signers "epg")
 248 (autoload 'epg-context-set-passphrase-callback "epg")
 249 (autoload 'epg-key-sub-key-list "epg")
 250 (autoload 'epg-sub-key-capability "epg")
 251 (autoload 'epg-sub-key-validity "epg")
 252 (autoload 'epg-sub-key-fingerprint "epg")
 253 (autoload 'epg-sign-string "epg")
 254 (autoload 'epg-encrypt-string "epg")
 255 (autoload 'epg-configuration "epg-config")
 256 (autoload 'epg-expand-group "epg-config")
 257
 258 (defvar mml1991-epg-secret-key-id-list nil)
 259
 260 (defun mml1991-epg-passphrase-callback (context key-id ignore)
 261   (if (eq key-id 'SYM)
 262       (epg-passphrase-callback-function context key-id nil)
 263     (let* ((entry (assoc key-id epg-user-id-alist))
 264            (passphrase
 265             (password-read
 266              (format "GnuPG passphrase for %s: "
 267                      (if entry
 268                          (cdr entry)
 269                        key-id))
 270              (if (eq key-id 'PIN)
 271                  "PIN"
 272                key-id))))
 273       (when passphrase
 274         (let ((password-cache-expiry mml1991-passphrase-cache-expiry))
 275           (password-cache-add key-id passphrase))
 276         (setq mml1991-epg-secret-key-id-list
 277               (cons key-id mml1991-epg-secret-key-id-list))
 278         (copy-sequence passphrase)))))
 279
 280 (defun mml1991-epg-find-usable-key (keys usage)
 281   (catch 'found
 282     (while keys
 283       (let ((pointer (epg-key-sub-key-list (car keys))))
 284         ;; The primary key will be marked as disabled, when the entire
 285         ;; key is disabled (see 12 Field, Format of colon listings, in
 286         ;; gnupg/doc/DETAILS)
 287         (unless (memq 'disabled (epg-sub-key-capability (car pointer)))
 288           (while pointer
 289             (if (and (memq usage (epg-sub-key-capability (car pointer)))
 290                      (not (memq (epg-sub-key-validity (car pointer))
 291                                 '(revoked expired))))
 292                 (throw 'found (car keys)))
 293             (setq pointer (cdr pointer)))))
 294       (setq keys (cdr keys)))))
 295
 296 ;; XXX: since gpg --list-secret-keys does not return validity of each
 297 ;; key, `mml1991-epg-find-usable-key' defined above is not enough for
 298 ;; secret keys.  The function `mml1991-epg-find-usable-secret-key'
 299 ;; below looks at appropriate public keys to check usability.
 300 (defun mml1991-epg-find-usable-secret-key (context name usage)
 301   (let ((secret-keys (epg-list-keys context name t))
 302         secret-key)
 303     (while (and (not secret-key) secret-keys)
 304       (if (mml1991-epg-find-usable-key
 305            (epg-list-keys context (epg-sub-key-fingerprint
 306                                    (car (epg-key-sub-key-list
 307                                          (car secret-keys)))))
 308            usage)
 309           (setq secret-key (car secret-keys)
 310                 secret-keys nil)
 311         (setq secret-keys (cdr secret-keys))))
 312     secret-key))
 313
 314 (defun mml1991-epg-sign (cont)
 315   (let ((context (epg-make-context))
 316         headers cte signer-key signers signature)
 317     (if (eq mm-sign-option 'guided)
 318         (setq signers (epa-select-keys context "Select keys for signing.
 319 If no one is selected, default secret key is used.  "
 320                                        mml1991-signers t))
 321       (if mml1991-signers
 322           (setq signers (delq nil
 323                               (mapcar
 324                                (lambda (name)
 325                                  (setq signer-key
 326                                        (mml1991-epg-find-usable-secret-key
 327                                         context name 'sign))
 328                                  (unless (or signer-key
 329                                              (y-or-n-p
 330                                               (format
 331                                                "No secret key for %s; skip it? "
 332                                                name)))
 333                                    (error "No secret key for %s" name))
 334                                  signer-key)
 335                                mml1991-signers)))))
 336     (epg-context-set-armor context t)
 337     (epg-context-set-textmode context t)
 338     (epg-context-set-signers context signers)
 339     (if mml1991-cache-passphrase
 340         (epg-context-set-passphrase-callback
 341          context
 342          #'mml1991-epg-passphrase-callback))
 343     ;; Don't sign headers.
 344     (goto-char (point-min))
 345     (when (re-search-forward "^$" nil t)
 346       (setq headers (buffer-substring (point-min) (point)))
 347       (save-restriction
 348         (narrow-to-region (point-min) (point))
 349         (setq cte (mail-fetch-field "content-transfer-encoding")))
 350       (forward-line 1)
 351       (delete-region (point-min) (point))
 352       (when cte
 353         (setq cte (intern (downcase cte)))
 354         (mm-decode-content-transfer-encoding cte)))
 355     (condition-case error
 356         (setq signature (epg-sign-string context (buffer-string) 'clear)
 357               mml1991-epg-secret-key-id-list nil)
 358       (error
 359        (while mml1991-epg-secret-key-id-list
 360          (password-cache-remove (car mml1991-epg-secret-key-id-list))
 361          (setq mml1991-epg-secret-key-id-list
 362                (cdr mml1991-epg-secret-key-id-list)))
 363        (signal (car error) (cdr error))))
 364     (delete-region (point-min) (point-max))
 365     (mm-with-unibyte-current-buffer
 366       (insert signature)
 367       (goto-char (point-min))
 368       (while (re-search-forward "\r+$" nil t)
 369         (replace-match "" t t))
 370       (when cte
 371         (mm-encode-content-transfer-encoding cte))
 372       (goto-char (point-min))
 373       (when headers
 374         (insert headers))
 375       (insert "\n"))
 376     t))
 377
 378 (defun mml1991-epg-encrypt (cont &optional sign)
 379   (goto-char (point-min))
 380   (when (re-search-forward "^$" nil t)
 381     (let ((cte (save-restriction
 382                  (narrow-to-region (point-min) (point))
 383                  (mail-fetch-field "content-transfer-encoding"))))
 384       ;; Strip MIME headers since it will be ASCII armored.
 385       (forward-line 1)
 386       (delete-region (point-min) (point))
 387       (when cte
 388         (mm-decode-content-transfer-encoding (intern (downcase cte))))))
 389   (let ((context (epg-make-context))
 390         (recipients
 391          (if (message-options-get 'message-recipients)
 392              (split-string
 393               (message-options-get 'message-recipients)
 394               "[ \f\t\n\r\v,]+")))
 395         recipient-key signer-key cipher signers config)
 396     (when mml1991-encrypt-to-self
 397       (unless mml1991-signers
 398         (error "mml1991-signers is not set"))
 399       (setq recipients (nconc recipients mml1991-signers)))
 400     ;; We should remove this check if epg-0.0.6 is released.
 401     (if (and (condition-case nil
 402                  (require 'epg-config)
 403                (error))
 404              (functionp #'epg-expand-group))
 405         (setq config (epg-configuration)
 406               recipients
 407               (apply #'nconc
 408                      (mapcar (lambda (recipient)
 409                                (or (epg-expand-group config recipient)
 410                                    (list recipient)))
 411                              recipients))))
 412     (if (eq mm-encrypt-option 'guided)
 413         (setq recipients
 414               (epa-select-keys context "Select recipients for encryption.
 415 If no one is selected, symmetric encryption will be performed.  "
 416                                recipients))
 417       (setq recipients
 418             (delq nil (mapcar
 419                        (lambda (name)
 420                          (setq recipient-key (mml1991-epg-find-usable-key
 421                                               (epg-list-keys context name)
 422                                               'encrypt))
 423                          (unless (or recipient-key
 424                                    (y-or-n-p
 425                                     (format "No public key for %s; skip it? "
 426                                             name)))
 427                            (error "No public key for %s" name))
 428                          recipient-key)
 429                        recipients)))
 430       (unless recipients
 431         (error "No recipient specified")))
 432     (when sign
 433       (if (eq mm-sign-option 'guided)
 434           (setq signers (epa-select-keys context "Select keys for signing.
 435 If no one is selected, default secret key is used.  "
 436                                          mml1991-signers t))
 437         (if mml1991-signers
 438             (setq signers (delq nil
 439                                 (mapcar
 440                                  (lambda (name)
 441                                    (mml1991-epg-find-usable-secret-key
 442                                     context name 'sign))
 443                                  mml1991-signers)))))
 444       (epg-context-set-signers context signers))
 445     (epg-context-set-armor context t)
 446     (epg-context-set-textmode context t)
 447     (if mml1991-cache-passphrase
 448         (epg-context-set-passphrase-callback
 449          context
 450          #'mml1991-epg-passphrase-callback))
 451     (condition-case error
 452         (setq cipher
 453               (epg-encrypt-string context (buffer-string) recipients sign)
 454               mml1991-epg-secret-key-id-list nil)
 455       (error
 456        (while mml1991-epg-secret-key-id-list
 457          (password-cache-remove (car mml1991-epg-secret-key-id-list))
 458          (setq mml1991-epg-secret-key-id-list
 459                (cdr mml1991-epg-secret-key-id-list)))
 460        (signal (car error) (cdr error))))
 461     (delete-region (point-min) (point-max))
 462     (insert "\n" cipher))
 463   t)
 464
 465 ;;;###autoload
 466 (defun mml1991-encrypt (cont &optional sign)
 467   (let ((func (nth 2 (assq mml1991-use mml1991-function-alist))))
 468     (if func
 469         (funcall func cont sign)
 470       (error "Cannot find encrypt function"))))
 471
 472 ;;;###autoload
 473 (defun mml1991-sign (cont)
 474   (let ((func (nth 1 (assq mml1991-use mml1991-function-alist))))
 475     (if func
 476         (funcall func cont)
 477       (error "Cannot find sign function"))))
 478
 479 (provide 'mml1991)
 480
 481 ;; Local Variables:
 482 ;; coding: utf-8
 483 ;; End:
 484
 485 ;;; mml1991.el ends here