X-Git-Url: http://cgit.sxemacs.org/?p=gnus;a=blobdiff_plain;f=lisp%2Fmml-sec.el;h=f526e058c21e36acf9ab6697507404f2c4a715b0;hp=9d64d57ba1633c3edcef400b3cf4fa5ff39586a0;hb=7067d9be35e2177e6b891ede1db93f9af6c7e234;hpb=55f610143f1f63a6cc448649d02a51a0b99c04f1 diff --git a/lisp/mml-sec.el b/lisp/mml-sec.el index 9d64d57ba..f526e058c 100644 --- a/lisp/mml-sec.el +++ b/lisp/mml-sec.el @@ -1,48 +1,173 @@ ;;; mml-sec.el --- A package with security functions for MML documents -;; Copyright (C) 2000 Free Software Foundation, Inc. + +;; Copyright (C) 2000-2016 Free Software Foundation, Inc. ;; Author: Simon Josefsson -;; This file is not part of GNU Emacs, but the same permissions apply. -;; GNU Emacs is free software; you can redistribute it and/or modify +;; This file is part of GNU Emacs. + +;; GNU Emacs 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. +;; the Free Software Foundation, either version 3 of the License, or +;; (at your option) any later version. ;; GNU Emacs 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 +;; 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 GNU Emacs; see the file COPYING. If not, write to the -;; Free Software Foundation, Inc., 59 Temple Place - Suite 330, -;; Boston, MA 02111-1307, USA. +;; along with GNU Emacs. If not, see . ;;; Commentary: ;;; Code: -(require 'smime) -(require 'mml2015) -(require 'mml-smime) (eval-when-compile (require 'cl)) +(require 'gnus-util) +(require 'epg) + +(autoload 'mail-strip-quoted-names "mail-utils") +(autoload 'mml2015-sign "mml2015") +(autoload 'mml2015-encrypt "mml2015") +(autoload 'mml1991-sign "mml1991") +(autoload 'mml1991-encrypt "mml1991") +(autoload 'message-fetch-field "message") +(autoload 'message-goto-body "message") +(autoload 'mml-insert-tag "mml") +(autoload 'mml-smime-sign "mml-smime") +(autoload 'mml-smime-encrypt "mml-smime") +(autoload 'mml-smime-sign-query "mml-smime") +(autoload 'mml-smime-encrypt-query "mml-smime") +(autoload 'mml-smime-verify "mml-smime") +(autoload 'mml-smime-verify-test "mml-smime") +(autoload 'epa--select-keys "epa") + (defvar mml-sign-alist '(("smime" mml-smime-sign-buffer mml-smime-sign-query) + ("pgp" mml-pgp-sign-buffer list) + ("pgpauto" mml-pgpauto-sign-buffer list) ("pgpmime" mml-pgpmime-sign-buffer list)) "Alist of MIME signer functions.") -(defvar mml-default-sign-method (caar mml-sign-alist) - "Default sign method.") +(defcustom mml-default-sign-method "pgpmime" + "Default sign method. +The string must have an entry in `mml-sign-alist'." + :version "22.1" + :type '(choice (const "smime") + (const "pgp") + (const "pgpauto") + (const "pgpmime") + string) + :group 'message) (defvar mml-encrypt-alist '(("smime" mml-smime-encrypt-buffer mml-smime-encrypt-query) + ("pgp" mml-pgp-encrypt-buffer list) + ("pgpauto" mml-pgpauto-sign-buffer list) ("pgpmime" mml-pgpmime-encrypt-buffer list)) "Alist of MIME encryption functions.") -(defvar mml-default-encrypt-method (caar mml-encrypt-alist) - "Default encryption method.") +(defcustom mml-default-encrypt-method "pgpmime" + "Default encryption method. +The string must have an entry in `mml-encrypt-alist'." + :version "22.1" + :type '(choice (const "smime") + (const "pgp") + (const "pgpauto") + (const "pgpmime") + string) + :group 'message) + +(defcustom mml-signencrypt-style-alist + '(("smime" separate) + ("pgp" combined) + ("pgpauto" combined) + ("pgpmime" combined)) + "Alist specifying if `signencrypt' results in two separate operations or not. +The first entry indicates the MML security type, valid entries include +the strings \"smime\", \"pgp\", and \"pgpmime\". The second entry is +a symbol `separate' or `combined' where `separate' means that MML signs +and encrypt messages in a two step process, and `combined' means that MML +signs and encrypt the message in one step. + +Note that the output generated by using a `combined' mode is NOT +understood by all PGP implementations, in particular PGP version +2 does not support it! See Info node `(message) Security' for +details." + :version "22.1" + :group 'message + :type '(repeat (list (choice (const :tag "S/MIME" "smime") + (const :tag "PGP" "pgp") + (const :tag "PGP/MIME" "pgpmime") + (string :tag "User defined")) + (choice (const :tag "Separate" separate) + (const :tag "Combined" combined))))) + +(defcustom mml-secure-verbose nil + "If non-nil, ask the user about the current operation more verbosely." + :group 'message + :type 'boolean) + +(defcustom mml-secure-cache-passphrase + (if (boundp 'password-cache) + password-cache + t) + "If t, cache OpenPGP or S/MIME passphrases inside Emacs. +Passphrase caching in Emacs is NOT recommended. Use gpg-agent instead. +See Info node `(message) Security'." + :group 'message + :type 'boolean) + +(defcustom mml-secure-passphrase-cache-expiry + (if (boundp 'password-cache-expiry) + password-cache-expiry + 16) + "How many seconds the passphrase is cached. +Whether the passphrase is cached at all is controlled by +`mml-secure-cache-passphrase'." + :group 'message + :type 'integer) + +(defcustom mml-secure-safe-bcc-list nil + "List of e-mail addresses that are safe to use in Bcc headers. +EasyPG encrypts e-mails to Bcc addresses, and the encrypted e-mail +by default identifies the used encryption keys, giving away the +Bcc'ed identities. Clearly, this contradicts the original goal of +*blind* copies. +For an academic paper explaining the problem, see URL +`http://crypto.stanford.edu/portia/papers/bb-bcc.pdf'. +Use this variable to specify e-mail addresses whose owners do not +mind if they are identifiable as recipients. This may be useful if +you use Bcc headers to encrypt e-mails to yourself." + :version "25.1" + :group 'message + :type '(repeat string)) + +;;; Configuration/helper functions + +(defun mml-signencrypt-style (method &optional style) + "Function for setting/getting the signencrypt-style used. Takes two +arguments, the method (e.g. \"pgp\") and optionally the mode +\(e.g. combined). If the mode is omitted, the current value is returned. + +For example, if you prefer to use combined sign & encrypt with +smime, putting the following in your Gnus startup file will +enable that behavior: + +\(mml-set-signencrypt-style \"smime\" combined) + +You can also customize or set `mml-signencrypt-style-alist' instead." + (let ((style-item (assoc method mml-signencrypt-style-alist))) + (if style-item + (if (or (eq style 'separate) + (eq style 'combined)) + ;; valid style setting? + (setf (second style-item) style) + ;; otherwise, just return the current value + (second style-item)) + (message "Warning, attempt to set invalid signencrypt style")))) ;;; Security functions @@ -50,16 +175,41 @@ (or (mml-smime-sign cont) (error "Signing failed... inspect message logs for errors"))) -(defun mml-smime-encrypt-buffer (cont) +(defun mml-smime-encrypt-buffer (cont &optional sign) + (when sign + (message "Combined sign and encrypt S/MIME not support yet") + (sit-for 1)) (or (mml-smime-encrypt cont) (error "Encryption failed... inspect message logs for errors"))) +(defun mml-pgp-sign-buffer (cont) + (or (mml1991-sign cont) + (error "Signing failed... inspect message logs for errors"))) + +(defun mml-pgp-encrypt-buffer (cont &optional sign) + (or (mml1991-encrypt cont sign) + (error "Encryption failed... inspect message logs for errors"))) + (defun mml-pgpmime-sign-buffer (cont) (or (mml2015-sign cont) (error "Signing failed... inspect message logs for errors"))) -(defun mml-pgpmime-encrypt-buffer (cont) - (or (mml2015-encrypt cont) +(defun mml-pgpmime-encrypt-buffer (cont &optional sign) + (or (mml2015-encrypt cont sign) + (error "Encryption failed... inspect message logs for errors"))) + +(defun mml-pgpauto-sign-buffer (cont) + (message-goto-body) + (or (if (re-search-backward "Content-Type: *multipart/.*" nil t) ; there must be a better way... + (mml2015-sign cont) + (mml1991-sign cont)) + (error "Encryption failed... inspect message logs for errors"))) + +(defun mml-pgpauto-encrypt-buffer (cont &optional sign) + (message-goto-body) + (or (if (re-search-backward "Content-Type: *multipart/.*" nil t) ; there must be a better way... + (mml2015-encrypt cont sign) + (mml1991-encrypt cont sign)) (error "Encryption failed... inspect message logs for errors"))) (defun mml-secure-part (method &optional sign) @@ -78,7 +228,7 @@ (when (string-match "[\"'\\~/*;() \t\n]" value) (setq value (prin1-to-string value))) (insert (format " %s=%s" key value)))))) - ((or (re-search-backward + ((or (re-search-backward (concat "^" (regexp-quote mail-header-separator) "\n") nil t) (re-search-forward (concat "^" (regexp-quote mail-header-separator) "\n") nil t)) @@ -87,6 +237,39 @@ (cons method tags)))) (t (error "The message is corrupted. No mail header separator")))))) +(defvar mml-secure-method + (if (equal mml-default-encrypt-method mml-default-sign-method) + mml-default-sign-method + "pgpmime") + "Current security method. Internal variable.") + +(defun mml-secure-sign (&optional method) + "Add MML tags to sign this MML part. +Use METHOD if given. Else use `mml-secure-method' or +`mml-default-sign-method'." + (interactive) + (mml-secure-part + (or method mml-secure-method mml-default-sign-method) + 'sign)) + +(defun mml-secure-encrypt (&optional method) + "Add MML tags to encrypt this MML part. +Use METHOD if given. Else use `mml-secure-method' or +`mml-default-sign-method'." + (interactive) + (mml-secure-part + (or method mml-secure-method mml-default-sign-method))) + +(defun mml-secure-sign-pgp () + "Add MML tags to PGP sign this MML part." + (interactive) + (mml-secure-part "pgp" 'sign)) + +(defun mml-secure-sign-pgpauto () + "Add MML tags to PGP-auto sign this MML part." + (interactive) + (mml-secure-part "pgpauto" 'sign)) + (defun mml-secure-sign-pgpmime () "Add MML tags to PGP/MIME sign this MML part." (interactive) @@ -97,6 +280,11 @@ (interactive) (mml-secure-part "smime" 'sign)) +(defun mml-secure-encrypt-pgp () + "Add MML tags to PGP encrypt this MML part." + (interactive) + (mml-secure-part "pgp")) + (defun mml-secure-encrypt-pgpmime () "Add MML tags to PGP/MIME encrypt this MML part." (interactive) @@ -107,6 +295,664 @@ (interactive) (mml-secure-part "smime")) +(defun mml-secure-is-encrypted-p () + "Check whether secure encrypt tag is present." + (save-excursion + (goto-char (point-min)) + (re-search-forward + (concat "^" (regexp-quote mail-header-separator) "\n" + "<#secure[^>]+encrypt") + nil t))) + +(defun mml-secure-bcc-is-safe () + "Check whether usage of Bcc is safe (or absent). +Bcc usage is safe in two cases: first, if the current message does +not contain an MML secure encrypt tag; +second, if the Bcc addresses are a subset of `mml-secure-safe-bcc-list'. +In all other cases, ask the user whether Bcc usage is safe. +Raise error if user answers no. +Note that this function does not produce a meaningful return value: +either an error is raised or not." + (when (mml-secure-is-encrypted-p) + (let ((bcc (mail-strip-quoted-names (message-fetch-field "bcc")))) + (when bcc + (let ((bcc-list (mapcar #'cadr + (mail-extract-address-components bcc t)))) + (unless (gnus-subsetp bcc-list mml-secure-safe-bcc-list) + (unless (yes-or-no-p "Message for encryption contains Bcc header.\ + This may give away all Bcc'ed identities to all recipients.\ + Are you sure that this is safe?\ + (Customize `mml-secure-safe-bcc-list' to avoid this warning.) ") + (error "Aborted")))))))) + +;; defuns that add the proper <#secure ...> tag to the top of the message body +(defun mml-secure-message (method &optional modesym) + (let ((mode (prin1-to-string modesym)) + (tags (append + (if (or (eq modesym 'sign) + (eq modesym 'signencrypt)) + (funcall (nth 2 (assoc method mml-sign-alist)))) + (if (or (eq modesym 'encrypt) + (eq modesym 'signencrypt)) + (funcall (nth 2 (assoc method mml-encrypt-alist)))))) + insert-loc) + (mml-unsecure-message) + (save-excursion + (goto-char (point-min)) + (cond ((re-search-forward + (concat "^" (regexp-quote mail-header-separator) "\n") nil t) + (goto-char (setq insert-loc (match-end 0))) + (unless (looking-at "<#secure") + (apply 'mml-insert-tag + 'secure 'method method 'mode mode tags))) + (t (error + "The message is corrupted. No mail header separator")))) + (when (eql insert-loc (point)) + (forward-line 1)))) + +(defun mml-unsecure-message () + "Remove security related MML tags from message." + (interactive) + (save-excursion + (goto-char (point-max)) + (when (re-search-backward "^<#secure.*>\n" nil t) + (delete-region (match-beginning 0) (match-end 0))))) + + +(defun mml-secure-message-sign (&optional method) + "Add MML tags to sign the entire message. +Use METHOD if given. Else use `mml-secure-method' or +`mml-default-sign-method'." + (interactive) + (mml-secure-message + (or method mml-secure-method mml-default-sign-method) + 'sign)) + +(defun mml-secure-message-sign-encrypt (&optional method) + "Add MML tag to sign and encrypt the entire message. +Use METHOD if given. Else use `mml-secure-method' or +`mml-default-sign-method'." + (interactive) + (mml-secure-message + (or method mml-secure-method mml-default-sign-method) + 'signencrypt)) + +(defun mml-secure-message-encrypt (&optional method) + "Add MML tag to encrypt the entire message. +Use METHOD if given. Else use `mml-secure-method' or +`mml-default-sign-method'." + (interactive) + (mml-secure-message + (or method mml-secure-method mml-default-sign-method) + 'encrypt)) + +(defun mml-secure-message-sign-smime () + "Add MML tag to encrypt/sign the entire message." + (interactive) + (mml-secure-message "smime" 'sign)) + +(defun mml-secure-message-sign-pgp () + "Add MML tag to encrypt/sign the entire message." + (interactive) + (mml-secure-message "pgp" 'sign)) + +(defun mml-secure-message-sign-pgpmime () + "Add MML tag to encrypt/sign the entire message." + (interactive) + (mml-secure-message "pgpmime" 'sign)) + +(defun mml-secure-message-sign-pgpauto () + "Add MML tag to encrypt/sign the entire message." + (interactive) + (mml-secure-message "pgpauto" 'sign)) + +(defun mml-secure-message-encrypt-smime (&optional dontsign) + "Add MML tag to encrypt and sign the entire message. +If called with a prefix argument, only encrypt (do NOT sign)." + (interactive "P") + (mml-secure-message "smime" (if dontsign 'encrypt 'signencrypt))) + +(defun mml-secure-message-encrypt-pgp (&optional dontsign) + "Add MML tag to encrypt and sign the entire message. +If called with a prefix argument, only encrypt (do NOT sign)." + (interactive "P") + (mml-secure-message "pgp" (if dontsign 'encrypt 'signencrypt))) + +(defun mml-secure-message-encrypt-pgpmime (&optional dontsign) + "Add MML tag to encrypt and sign the entire message. +If called with a prefix argument, only encrypt (do NOT sign)." + (interactive "P") + (mml-secure-message "pgpmime" (if dontsign 'encrypt 'signencrypt))) + +(defun mml-secure-message-encrypt-pgpauto (&optional dontsign) + "Add MML tag to encrypt and sign the entire message. +If called with a prefix argument, only encrypt (do NOT sign)." + (interactive "P") + (mml-secure-message "pgpauto" (if dontsign 'encrypt 'signencrypt))) + +;;; Common functionality for mml1991.el, mml2015.el, mml-smime.el + +(define-obsolete-variable-alias 'mml1991-signers 'mml-secure-openpgp-signers) +(define-obsolete-variable-alias 'mml2015-signers 'mml-secure-openpgp-signers) +(defcustom mml-secure-openpgp-signers nil + "A list of your own key ID(s) which will be used to sign OpenPGP messages. +If set, it is added to the setting of `mml-secure-openpgp-sign-with-sender'." + :group 'mime-security + :type '(repeat (string :tag "Key ID"))) + +(define-obsolete-variable-alias 'mml-smime-signers 'mml-secure-smime-signers) +(defcustom mml-secure-smime-signers nil + "A list of your own key ID(s) which will be used to sign S/MIME messages. +If set, it is added to the setting of `mml-secure-smime-sign-with-sender'." + :group 'mime-security + :type '(repeat (string :tag "Key ID"))) + +(define-obsolete-variable-alias + 'mml1991-encrypt-to-self 'mml-secure-openpgp-encrypt-to-self) +(define-obsolete-variable-alias + 'mml2015-encrypt-to-self 'mml-secure-openpgp-encrypt-to-self) +(defcustom mml-secure-openpgp-encrypt-to-self nil + "List of own key ID(s) or t; determines additional recipients with OpenPGP. +If t, also encrypt to key for message sender; if list, encrypt to those keys. +With this variable, you can ensure that you can decrypt your own messages. +Alternatives to this variable include Bcc'ing the message to yourself or +using the encrypt-to or hidden-encrypt-to option in gpg.conf (see man gpg(1)). +Note that this variable and the encrypt-to option give away your identity +for *every* encryption without warning, which is not what you want if you are +using, e.g., remailers. +Also, use of Bcc gives away your identity for *every* encryption without +warning, which is a bug, see: +https://debbugs.gnu.org/cgi/bugreport.cgi?bug=18718" + :group 'mime-security + :type '(choice (const :tag "None" nil) + (const :tag "From address" t) + (repeat (string :tag "Key ID")))) + +(define-obsolete-variable-alias + 'mml-smime-encrypt-to-self 'mml-secure-smime-encrypt-to-self) +(defcustom mml-secure-smime-encrypt-to-self nil + "List of own key ID(s) or t; determines additional recipients with S/MIME. +If t, also encrypt to key for message sender; if list, encrypt to those keys. +With this variable, you can ensure that you can decrypt your own messages. +Alternatives to this variable include Bcc'ing the message to yourself or +using the encrypt-to option in gpgsm.conf (see man gpgsm(1)). +Note that this variable and the encrypt-to option give away your identity +for *every* encryption without warning, which is not what you want if you are +using, e.g., remailers. +Also, use of Bcc gives away your identity for *every* encryption without +warning, which is a bug, see: +https://debbugs.gnu.org/cgi/bugreport.cgi?bug=18718" + :group 'mime-security + :type '(choice (const :tag "None" nil) + (const :tag "From address" t) + (repeat (string :tag "Key ID")))) + +(define-obsolete-variable-alias + 'mml2015-sign-with-sender 'mml-secure-openpgp-sign-with-sender) +;mml1991-sign-with-sender did never exist. +(defcustom mml-secure-openpgp-sign-with-sender nil + "If t, use message sender to find an OpenPGP key to sign with." + :group 'mime-security + :type 'boolean) + +(define-obsolete-variable-alias + 'mml-smime-sign-with-sender 'mml-secure-smime-sign-with-sender) +(defcustom mml-secure-smime-sign-with-sender nil + "If t, use message sender to find an S/MIME key to sign with." + :group 'mime-security + :type 'boolean) + +(define-obsolete-variable-alias + 'mml2015-always-trust 'mml-secure-openpgp-always-trust) +;mml1991-always-trust did never exist. +(defcustom mml-secure-openpgp-always-trust t + "If t, skip key validation of GnuPG on encryption." + :group 'mime-security + :type 'boolean) + +(defcustom mml-secure-fail-when-key-problem nil + "If t, raise an error if some key is missing or several keys exist. +Otherwise, ask the user." + :group 'mime-security + :type 'boolean) + +(defcustom mml-secure-key-preferences + '((OpenPGP (sign) (encrypt)) (CMS (sign) (encrypt))) + "Protocol- and usage-specific fingerprints of preferred keys. +This variable is only relevant if a recipient owns multiple key pairs (for +encryption) or you own multiple key pairs (for signing). In such cases, +you will be asked which key(s) should be used, and your choice can be +customized in this variable." + :group 'mime-security + :type '(alist :key-type (symbol :tag "Protocol") :value-type + (alist :key-type (symbol :tag "Usage") :value-type + (alist :key-type (string :tag "Name") :value-type + (repeat (string :tag "Fingerprint")))))) + +(defun mml-secure-cust-usage-lookup (context usage) + "Return preferences for CONTEXT and USAGE." + (let* ((protocol (epg-context-protocol context)) + (protocol-prefs (cdr (assoc protocol mml-secure-key-preferences)))) + (assoc usage protocol-prefs))) + +(defun mml-secure-cust-fpr-lookup (context usage name) + "Return fingerprints of preferred keys for CONTEXT, USAGE, and NAME." + (let* ((usage-prefs (mml-secure-cust-usage-lookup context usage)) + (fprs (assoc name (cdr usage-prefs)))) + (when fprs + (cdr fprs)))) + +(defun mml-secure-cust-record-keys (context usage name keys &optional save) + "For CONTEXT, USAGE, and NAME record fingerprint(s) of KEYS. +If optional SAVE is not nil, save customized fingerprints. +Return keys." + (assert keys) + (let* ((usage-prefs (mml-secure-cust-usage-lookup context usage)) + (curr-fprs (cdr (assoc name (cdr usage-prefs)))) + (key-fprs (mapcar 'mml-secure-fingerprint keys)) + (new-fprs (gnus-union curr-fprs key-fprs))) + (if curr-fprs + (setcdr (assoc name (cdr usage-prefs)) new-fprs) + (setcdr usage-prefs (cons (cons name new-fprs) (cdr usage-prefs)))) + (when save + (customize-save-variable + 'mml-secure-key-preferences mml-secure-key-preferences)) + keys)) + +(defun mml-secure-cust-remove-keys (context usage name) + "Remove keys for CONTEXT, USAGE, and NAME. +Return t if a customization for NAME was present (and has been removed)." + (let* ((usage-prefs (mml-secure-cust-usage-lookup context usage)) + (current (assoc name usage-prefs))) + (when current + (setcdr usage-prefs (remove current (cdr usage-prefs))) + t))) + +(defvar mml-secure-secret-key-id-list nil) + +(defun mml-secure-add-secret-key-id (key-id) + "Record KEY-ID in list of secret keys." + (add-to-list 'mml-secure-secret-key-id-list key-id)) + +(defun mml-secure-clear-secret-key-id-list () + "Remove passwords from cache and clear list of secret keys." + ;; Loosely based on code inside mml2015-epg-encrypt, + ;; mml2015-epg-clear-decrypt, and mml2015-epg-decrypt + (dolist (key-id mml-secure-secret-key-id-list nil) + (password-cache-remove key-id)) + (setq mml-secure-secret-key-id-list nil)) + +(defvar mml1991-cache-passphrase) +(defvar mml1991-passphrase-cache-expiry) + +(defun mml-secure-cache-passphrase-p (protocol) + "Return t if OpenPGP or S/MIME passphrases should be cached for PROTOCOL. +Passphrase caching in Emacs is NOT recommended. Use gpg-agent instead." + (or (and (eq 'OpenPGP protocol) + (or mml-secure-cache-passphrase + (and (boundp 'mml2015-cache-passphrase) + mml2015-cache-passphrase) + (and (boundp 'mml1991-cache-passphrase) + mml1991-cache-passphrase))) + (and (eq 'CMS protocol) + (or mml-secure-cache-passphrase + (and (boundp 'mml-smime-cache-passphrase) + mml-smime-cache-passphrase))))) + +(defun mml-secure-cache-expiry-interval (protocol) + "Return time in seconds to cache passphrases for PROTOCOL. +Passphrase caching in Emacs is NOT recommended. Use gpg-agent instead." + (or (and (eq 'OpenPGP protocol) + (or (and (boundp 'mml2015-passphrase-cache-expiry) + mml2015-passphrase-cache-expiry) + (and (boundp 'mml1991-passphrase-cache-expiry) + mml1991-passphrase-cache-expiry) + mml-secure-passphrase-cache-expiry)) + (and (eq 'CMS protocol) + (or (and (boundp 'mml-smime-passphrase-cache-expiry) + mml-smime-passphrase-cache-expiry) + mml-secure-passphrase-cache-expiry)))) + +(defun mml-secure-passphrase-callback (context key-id standard) + "Ask for passphrase in CONTEXT for KEY-ID for STANDARD. +The passphrase is read and cached." + ;; Based on mml2015-epg-passphrase-callback. + (if (eq key-id 'SYM) + (epg-passphrase-callback-function context key-id nil) + (let* ((password-cache-key-id + (if (eq key-id 'PIN) + "PIN" + key-id)) + (entry (assoc key-id epg-user-id-alist)) + (passphrase + (password-read + (if (eq key-id 'PIN) + "Passphrase for PIN: " + (if entry + (format "Passphrase for %s %s: " key-id (cdr entry)) + (format "Passphrase for %s: " key-id))) + ;; TODO: With mml-smime.el, password-cache-key-id is not passed + ;; as argument to password-read. + ;; Is that on purpose? If so, the following needs to be placed + ;; inside an if statement. + password-cache-key-id))) + (when passphrase + (let ((password-cache-expiry (mml-secure-cache-expiry-interval + (epg-context-protocol context)))) + (password-cache-add password-cache-key-id passphrase)) + (mml-secure-add-secret-key-id password-cache-key-id) + (copy-sequence passphrase))))) + +(defun mml-secure-check-user-id (key recipient) + "Check whether KEY has a non-revoked, non-expired UID for RECIPIENT." + ;; Based on mml2015-epg-check-user-id. + (let ((uids (epg-key-user-id-list key))) + (catch 'break + (dolist (uid uids nil) + (if (and (stringp (epg-user-id-string uid)) + (equal (car (mail-header-parse-address + (epg-user-id-string uid))) + (car (mail-header-parse-address + recipient))) + (not (memq (epg-user-id-validity uid) + '(revoked expired)))) + (throw 'break t)))))) + +(defun mml-secure-secret-key-exists-p (context subkey) + "Return t if keyring for CONTEXT contains secret key for public SUBKEY." + (let* ((fpr (epg-sub-key-fingerprint subkey)) + (candidates (epg-list-keys context fpr 'secret)) + (candno (length candidates))) + ;; If two or more subkeys with the same fingerprint exist, something is + ;; terribly wrong. + (when (>= candno 2) + (error "Found %d secret keys with same fingerprint %s" candno fpr)) + (= 1 candno))) + +(defun mml-secure-check-sub-key (context key usage &optional fingerprint) + "Check whether in CONTEXT the public KEY has a usable subkey for USAGE. +This is the case if KEY is not disabled, and there is a subkey for +USAGE that is neither revoked nor expired. Additionally, if optional +FINGERPRINT is present and if it is not the primary key's fingerprint, then +the returned subkey must have that FINGERPRINT. FINGERPRINT must consist of +hexadecimal digits only (no leading \"0x\" allowed). +If USAGE is not `encrypt', then additionally an appropriate secret key must +be present in the keyring." + ;; Based on mml2015-epg-check-sub-key, extended by + ;; - check for secret keys if usage is not 'encrypt and + ;; - check for new argument FINGERPRINT. + (let* ((subkeys (epg-key-sub-key-list key)) + (primary (car subkeys)) + (fpr (epg-sub-key-fingerprint primary))) + ;; The primary key will be marked as disabled, when the entire + ;; key is disabled (see 12 Field, Format of colon listings, in + ;; gnupg/doc/DETAILS) + (unless (memq 'disabled (epg-sub-key-capability primary)) + (catch 'break + (dolist (subkey subkeys nil) + (if (and (memq usage (epg-sub-key-capability subkey)) + (not (memq (epg-sub-key-validity subkey) + '(revoked expired))) + (or (eq 'encrypt usage) ; Encryption works with public key. + ;; In contrast, signing requires secret key. + (mml-secure-secret-key-exists-p context subkey)) + (or (not fingerprint) + (gnus-string-match-p (concat fingerprint "$") fpr) + (gnus-string-match-p (concat fingerprint "$") + (epg-sub-key-fingerprint subkey)))) + (throw 'break t))))))) + +(defun mml-secure-find-usable-keys (context name usage &optional justone) + "In CONTEXT return a list of keys for NAME and USAGE. +If USAGE is `encrypt' public keys are returned, otherwise secret ones. +Only non-revoked and non-expired keys are returned whose primary key is +not disabled. +NAME can be an e-mail address or a key ID. +If NAME just consists of hexadecimal digits (possibly prefixed by \"0x\"), it +is treated as key ID for which at most one key must exist in the keyring. +Otherwise, NAME is treated as user ID, for which no keys are returned if it +is expired or revoked. +If optional JUSTONE is not nil, return the first key instead of a list." + (let* ((keys (epg-list-keys context name)) + (iskeyid (string-match "\\(0x\\)?\\([0-9a-fA-F]\\{8,\\}\\)" name)) + (fingerprint (match-string 2 name)) + result) + (when (and iskeyid (>= (length keys) 2)) + (error + "Name %s (for %s) looks like a key ID but multiple keys found" + name usage)) + (catch 'break + (dolist (key keys result) + (if (and (or iskeyid + (mml-secure-check-user-id key name)) + (mml-secure-check-sub-key context key usage fingerprint)) + (if justone + (throw 'break key) + (push key result))))))) + +(defun mml-secure-select-preferred-keys (context names usage) + "Return list of preferred keys in CONTEXT for NAMES and USAGE. +This inspects the keyrings to find keys for each name in NAMES. If several +keys are found for a name, `mml-secure-select-keys' is used to look for +customized preferences or have the user select preferable ones. +When `mml-secure-fail-when-key-problem' is t, fail with an error in +case of missing, outdated, or multiple keys." + ;; Loosely based on code appearing inside mml2015-epg-sign and + ;; mml2015-epg-encrypt. + (apply + #'nconc + (mapcar + (lambda (name) + (let* ((keys (mml-secure-find-usable-keys context name usage)) + (keyno (length keys))) + (cond ((= 0 keyno) + (when (or mml-secure-fail-when-key-problem + (not (y-or-n-p + (format "No %s key for %s; skip it? " + usage name)))) + (error "No %s key for %s" usage name))) + ((= 1 keyno) keys) + (t (mml-secure-select-keys context name keys usage))))) + names))) + +(defun mml-secure-fingerprint (key) + "Return fingerprint for public KEY." + (epg-sub-key-fingerprint (car (epg-key-sub-key-list key)))) + +(defun mml-secure-filter-keys (keys fprs) + "Filter KEYS to subset with fingerprints in FPRS." + (when keys + (if (member (mml-secure-fingerprint (car keys)) fprs) + (cons (car keys) (mml-secure-filter-keys (cdr keys) fprs)) + (mml-secure-filter-keys (cdr keys) fprs)))) + +(defun mml-secure-normalize-cust-name (name) + "Normalize NAME to be used for customization. +Currently, remove ankle brackets." + (if (string-match "^<\\(.*\\)>$" name) + (match-string 1 name) + name)) + +(defun mml-secure-select-keys (context name keys usage) + "In CONTEXT for NAME select among KEYS for USAGE. +KEYS should be a list with multiple entries. +NAME is normalized first as customized keys are inspected. +When `mml-secure-fail-when-key-problem' is t, fail with an error in case of +outdated or multiple keys." + (let* ((nname (mml-secure-normalize-cust-name name)) + (fprs (mml-secure-cust-fpr-lookup context usage nname)) + (usable-fprs (mapcar 'mml-secure-fingerprint keys))) + (if fprs + (if (gnus-subsetp fprs usable-fprs) + (mml-secure-filter-keys keys fprs) + (mml-secure-cust-remove-keys context usage nname) + (let ((diff (gnus-setdiff fprs usable-fprs))) + (if mml-secure-fail-when-key-problem + (error "Customization of %s keys for %s outdated" usage nname) + (mml-secure-select-keys-1 + context nname keys usage (format "\ +Customized keys + (%s) +for %s not available any more. +Select anew. " + diff nname))))) + (if mml-secure-fail-when-key-problem + (error "Multiple %s keys for %s" usage nname) + (mml-secure-select-keys-1 + context nname keys usage (format "\ +Multiple %s keys for: + %s +Select preferred one(s). " + usage nname)))))) + +(defun mml-secure-select-keys-1 (context name keys usage message) + "In CONTEXT for NAME let user select among KEYS for USAGE, showing MESSAGE. +Return selected keys." + (let* ((selected (epa--select-keys message keys)) + (selno (length selected)) + ;; TODO: y-or-n-p does not always resize the echo area but may + ;; truncate the message. Why? The following does not help. + ;; yes-or-no-p shows full message, though. + (message-truncate-lines nil)) + (if selected + (if (y-or-n-p + (format "%d %s key(s) selected. Store for %s? " + selno usage name)) + (mml-secure-cust-record-keys context usage name selected 'save) + selected) + (unless (y-or-n-p + (format "No %s key for %s; skip it? " usage name)) + (error "No %s key for %s" usage name))))) + +(defun mml-secure-signer-names (protocol sender) + "Determine signer names for PROTOCOL and message from SENDER. +Returned names may be e-mail addresses or key IDs and are determined based +on `mml-secure-openpgp-signers' and `mml-secure-openpgp-sign-with-sender' with +OpenPGP or `mml-secure-smime-signers' and `mml-secure-smime-sign-with-sender' +with S/MIME." + (if (eq 'OpenPGP protocol) + (append mml-secure-openpgp-signers + (if (and mml-secure-openpgp-sign-with-sender sender) + (list (concat "<" sender ">")))) + (append mml-secure-smime-signers + (if (and mml-secure-smime-sign-with-sender sender) + (list (concat "<" sender ">")))))) + +(defun mml-secure-signers (context signer-names) + "Determine signing keys in CONTEXT from SIGNER-NAMES. +If `mm-sign-option' is `guided', the user is asked to choose. +Otherwise, `mml-secure-select-preferred-keys' is used." + ;; Based on code appearing inside mml2015-epg-sign and + ;; mml2015-epg-encrypt. + (if (eq mm-sign-option 'guided) + (epa-select-keys context "\ +Select keys for signing. +If no one is selected, default secret key is used. " + signer-names t) + (mml-secure-select-preferred-keys context signer-names 'sign))) + +(defun mml-secure-self-recipients (protocol sender) + "Determine additional recipients based on encrypt-to-self variables. +PROTOCOL specifies OpenPGP or S/MIME for a message from SENDER." + (let ((encrypt-to-self + (if (eq 'OpenPGP protocol) + mml-secure-openpgp-encrypt-to-self + mml-secure-smime-encrypt-to-self))) + (when encrypt-to-self + (if (listp encrypt-to-self) + encrypt-to-self + (list sender))))) + +(defun mml-secure-recipients (protocol context config sender) + "Determine encryption recipients. +PROTOCOL specifies OpenPGP or S/MIME with matching CONTEXT and CONFIG +for a message from SENDER." + ;; Based on code appearing inside mml2015-epg-encrypt. + (let ((recipients + (apply #'nconc + (mapcar + (lambda (recipient) + (or (epg-expand-group config recipient) + (list (concat "<" recipient ">")))) + (split-string + (or (message-options-get 'message-recipients) + (message-options-set 'message-recipients + (read-string "Recipients: "))) + "[ \f\t\n\r\v,]+"))))) + (nconc recipients (mml-secure-self-recipients protocol sender)) + (if (eq mm-encrypt-option 'guided) + (setq recipients + (epa-select-keys context "\ +Select recipients for encryption. +If no one is selected, symmetric encryption will be performed. " + recipients)) + (setq recipients + (mml-secure-select-preferred-keys context recipients 'encrypt)) + (unless recipients + (error "No recipient specified"))) + recipients)) + +(defun mml-secure-epg-encrypt (protocol cont &optional sign) + ;; Based on code appearing inside mml2015-epg-encrypt. + (let* ((context (epg-make-context protocol)) + (config (epg-configuration)) + (sender (message-options-get 'message-sender)) + (recipients (mml-secure-recipients protocol context config sender)) + (signer-names (mml-secure-signer-names protocol sender)) + cipher signers) + (when sign + (setq signers (mml-secure-signers context signer-names)) + (epg-context-set-signers context signers)) + (when (eq 'OpenPGP protocol) + (epg-context-set-armor context t) + (epg-context-set-textmode context t)) + (when (mml-secure-cache-passphrase-p protocol) + (epg-context-set-passphrase-callback + context + (cons 'mml-secure-passphrase-callback protocol))) + (condition-case error + (setq cipher + (if (eq 'OpenPGP protocol) + (epg-encrypt-string context (buffer-string) recipients sign + mml-secure-openpgp-always-trust) + (epg-encrypt-string context (buffer-string) recipients)) + mml-secure-secret-key-id-list nil) + (error + (mml-secure-clear-secret-key-id-list) + (signal (car error) (cdr error)))) + cipher)) + +(defun mml-secure-epg-sign (protocol mode) + ;; Based on code appearing inside mml2015-epg-sign. + (let* ((context (epg-make-context protocol)) + (sender (message-options-get 'message-sender)) + (signer-names (mml-secure-signer-names protocol sender)) + (signers (mml-secure-signers context signer-names)) + signature micalg) + (when (eq 'OpenPGP protocol) + (epg-context-set-armor context t) + (epg-context-set-textmode context t)) + (epg-context-set-signers context signers) + (when (mml-secure-cache-passphrase-p protocol) + (epg-context-set-passphrase-callback + context + (cons 'mml-secure-passphrase-callback protocol))) + (condition-case error + (setq signature + (if (eq 'OpenPGP protocol) + (epg-sign-string context (buffer-string) mode) + (epg-sign-string context + (mm-replace-in-string (buffer-string) + "\n" "\r\n") t)) + mml-secure-secret-key-id-list nil) + (error + (mml-secure-clear-secret-key-id-list) + (signal (car error) (cdr error)))) + (if (epg-context-result-for context 'sign) + (setq micalg (epg-new-signature-digest-algorithm + (car (epg-context-result-for context 'sign))))) + (cons signature micalg))) + (provide 'mml-sec) ;;; mml-sec.el ends here