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mc-gpg.el
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mc-gpg.el
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;; mc-gpg.el, GPG support for Mailcrypt
;; Copyright (C) 1995 Jin Choi <jin@atype.com>
;; Patrick LoPresti <patl@lcs.mit.edu>
;; 1998 Brian Warner <warner@lothar.com>
;;{{{ Licensing
;; This file is intended to be used with GNU Emacs.
;; 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 GNU Emacs; see the file COPYING. If not, write to
;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
;;}}}
(require 'mailcrypt)
; pieces to do:
; #key lookup?
; #mc-gpg-encrypt-region
; need to deal with untrusted keys, missing keys (offer to fetch), --throw
; #mc-gpg-decrypt-region [anything not clearsigned] (a,as,ae,ase)
; need to implement signature-key fetch, ponder --throw-keyid case
; keys without passphrases, sigs with bad algorithms (ignore sig? warn?)
; #mc-gpg-sign-region (clearsign/notclearsign)
; #mc-gpg-verify-region [clearsigned only] (ok/badsig/missingkey/corruptmsg)
; #mc-gpg-insert-public-key (comment, altkeyring)
; #mc-gpg-snarf-keys (one, multiple, old, corrupt)
; key fetching (is there a GPG key server yet?)
; clean up use of buffers, #kill off old tmp buffers
; in verify-region, print date of signature too
; ~maybe have bad-signature message print keyid/date? (no, sig is invalid,
; ~ anything other than its invalidity is misleading)
; make messages shorter (get it all to fit in echo area)
; enhancements I'd like to add
; trustdb status reporting during encryption/decryption: show the best trust
; path to the recipient/signer?
; completion on local id when signing (--list-secret-keys should know them)
; algorithm preferences, possibly by destination user
; (this is embedded in gpg)
; extra options, possibly by destination user. Maybe for pgp5.0/pgp2.6 compat?
; rfc2015 operation (MIME: application/pgp-signature, etc)
; signature dates are currently reported with just the date. Find a time
; formatting function and use the longtime in the VALIDSIG message.
; mc-gpg-alternate-keyring seems dubious.. have two options, public/private?
; using a shell introduces concerns about quoting and such. If the name of a
; key used as a recipient or as a mc-gpg-user-id (a key to sign with) has a
; double quote or ! or weird stuff, things could break.
; encrypting to a nontrusted key is problematic: when not in --batch mode,
; gpg warns the user and asks if they want to use the key anyway. In --batch
; mode, it fails, even if we give --yes. Worse yet, if we encrypt to multiple
; recipients, the untrusted ones get dropped withou flagging an error (stderr
; does get a message, but it doesn't indicate which keys had a problem)
(defvar mc-gpg-user-id (user-login-name)
"*GPG ID of your default identity.")
(defvar mc-gpg-path "gpg" "*The GPG executable.")
(defvar mc-gpg-display-snarf-output nil
"*If t, pop up the GPG output window when snarfing keys.")
(defvar mc-gpg-always-fetch 'never
"*If t, always fetch missing keys. If 'never, never fetch. If nil,
ask the user.")
(defvar mc-gpg-alternate-keyring nil
"*Public keyring to use instead of default.")
(defvar mc-gpg-comment
(format "Processed by Mailcrypt %s <http://mailcrypt.sourceforge.net/>"
mc-version)
"*Comment field to appear in ASCII armor output. If nil, let GPG use its
default.")
(defconst mc-gpg-msg-begin-line "^-----BEGIN PGP MESSAGE-----\r?$"
"Text for start of GPG message delimiter.")
(defconst mc-gpg-msg-end-line "^-----END PGP MESSAGE-----\r?$"
"Text for end of GPG message delimiter.")
(defconst mc-gpg-signed-begin-line "^-----BEGIN PGP SIGNED MESSAGE-----\r?$"
"Text for start of GPG signed messages.")
(defconst mc-gpg-signed-end-line "^-----END PGP SIGNATURE-----\r?$"
"Text for end of GPG signed messages.")
(defconst mc-gpg-key-begin-line "^-----BEGIN PGP PUBLIC KEY BLOCK-----\r?$"
"Text for start of GPG public key.")
(defconst mc-gpg-key-end-line "^-----END PGP PUBLIC KEY BLOCK-----\r?$"
"Text for end of GPG public key.")
(defvar mc-gpg-extra-args nil
"Extra arguments to pass to all invocations of gpg. Used during debugging to
set --homedir, to use special test keys instead of the developer's normal
keyring.")
(defvar mc-gpg-debug-buffer nil
"A buffer for debugging messages. If nil, no debugging messages are logged.
BEWARE! Sensitive data (including your passphrase) is put here. Set this with:
(setq mc-gpg-debug-buffer (get-buffer-create \"mc debug\"))")
;; we use with-current-buffer for clarity. emacs19 doesn't have it. This
;; code is cribbed from lazy-lock.el which does the same thing
(eval-when-compile
;; We use this for clarity and speed. Borrowed from a future Emacs.
(or (fboundp 'with-current-buffer)
(defmacro with-current-buffer (buffer &rest body)
"Execute the forms in BODY with BUFFER as the current buffer.
The value returned is the value of the last form in BODY."
(` (save-excursion (set-buffer (, buffer)) (,@ body)))))
)
(defun mc-gpg-debug-print (string)
(if (and (boundp 'mc-gpg-debug-buffer) mc-gpg-debug-buffer)
(print string mc-gpg-debug-buffer)))
;; the insert parser will return '(t) and insert the whole of stdout if
;; rc == 0, and will return '(nil rc stderr) if rc != 0
(defun mc-gpg-insert-parser (stdoutbuf stderrbuf statusbuf rc parserdata)
(mc-gpg-debug-print
(format "(mc-gpg-generic-parser stdoutbuf=%s stderrbuf=%s rc=%s"
stdoutbuf stderrbuf rc))
(if (= rc 0)
'(t (t))
(list nil nil rc (with-current-buffer stderrbuf (buffer-string))))
)
;; the null parser returns rc and never inserts anything
(defun mc-gpg-null-parser (stdoutbuf stderrbuf statusbuf rc parserdata)
(list nil rc))
; utility function (variant of mc-process-region):
; take region in current buffer, send as stdin to a process
; maybe send in a passphrase first
; three buffers of output are collected: stdout, stderr, and --status-fd
;
; parser is called with stdoutbuf as the current buffer as
; (parser stdoutbuf stderrbuf statusbuf rc parserdata)
; and is expected to return a list:
; '(REPLACEP RESULT)
;
; if REPLACEP is true, the original buffer's [beg..end] will be replaced by
; the stdout data buffer's contents (all of it). Otherwise the original buffer
; is left alone. RESULT (specifically (cdr parser-return-value)) is returned
; by mc-gpg-process-region.
(defun mc-gpg-process-region (beg end passwd program args parser bufferdummy
&optional parserdata)
(let ((obuf (current-buffer))
(process-connection-type nil)
(shell-file-name "/bin/sh") ;; ??? force? need sh (not tcsh) for "2>"
; other local vars
mybuf
stderr-tempfilename stderr-buf
status-tempfilename status-buf
proc rc status parser-result
)
(mc-gpg-debug-print (format
"(mc-gpg-process-region beg=%s end=%s passwd=%s program=%s args=%s parser=%s bufferdummy=%s)"
beg end passwd program args parser bufferdummy))
(setq stderr-tempfilename
(make-temp-name (expand-file-name "mailcrypt-gpg-stderr-"
mc-temp-directory)))
(setq status-tempfilename
(make-temp-name (expand-file-name "mailcrypt-gpg-status-"
mc-temp-directory)))
(unwind-protect
(progn
;; get output places ready
(setq mybuf (get-buffer-create " *mailcrypt stdout temp"))
(set-buffer mybuf)
(erase-buffer)
;; set the stdout buffer to be multibyte, so it can handle
;; whatever characters come back from GPG. These may be non-ASCII,
;; and unibyte buffers can't handle those correctly. If emacs is
;; in unibyte mode (such as when standard-display-european is
;; active), the multibyte characters will be downgraded to unibyte
;; when they are copied back into the email buffer. iso-latin-1
;; characters will survive this transition, others will not (but
;; then you wouldn't be using standard-display-european anyway).
(set-buffer-multibyte t)
(set-buffer obuf)
(buffer-disable-undo mybuf)
(if passwd
(setq args (append '("--passphrase-fd" "0") args)))
(setq args (append (list (concat "2>" stderr-tempfilename)) args))
(setq args (append (list (concat "3>" status-tempfilename)) args))
(setq args (append '("--status-fd" "3") args))
(if mc-gpg-extra-args
(setq args (append mc-gpg-extra-args args)))
(mc-gpg-debug-print (format "prog is %s, args are %s"
program
(mapconcat '(lambda (x)
(format "'%s'" x))
args " ")))
(setq proc
(apply 'start-process-shell-command "*GPG*" mybuf
program args))
;; send in passwd if necessary
(if passwd
(progn
(process-send-string proc (concat passwd "\n"))
(or mc-passwd-timeout (mc-deactivate-passwd t))))
;; send in the region
(process-send-region proc beg end)
;; finish it off
(process-send-eof proc)
;; wait for it to finish
(while (eq 'run (process-status proc))
(accept-process-output proc 5))
;; remember result codes
(setq status (process-status proc))
(setq rc (process-exit-status proc))
(mc-gpg-debug-print (format "prog finished, rc=%s" rc))
;; Hack to force a status_notify() in Emacs 19.29
(delete-process proc)
;; remove the annoying "yes your process has finished" message
(set-buffer mybuf)
(goto-char (point-max))
(if (re-search-backward "\nProcess \\*GPG.*\n\\'" nil t)
(delete-region (match-beginning 0) (match-end 0)))
(goto-char (point-min))
;; CRNL -> NL
(while (search-forward "\r\n" nil t)
(replace-match "\n"))
;; ponder process death: signal, not just rc!=0
(if (or (eq 'stop status) (eq 'signal status))
;; process died
(error "%s exited abnormally: '%s'" program rc) ;;is rc a string?
)
(if (= 127 rc)
(error "%s could not be found" program) ;; at least on my system
)
;; fill stderr buf
(setq stderr-buf (get-buffer-create " *mailcrypt stderr temp"))
(buffer-disable-undo stderr-buf)
(set-buffer stderr-buf)
(erase-buffer)
(insert-file-contents stderr-tempfilename)
;; fill status buf
(setq status-buf (get-buffer-create " *mailcrypt status temp"))
(buffer-disable-undo status-buf)
(set-buffer status-buf)
(erase-buffer)
(insert-file-contents status-tempfilename)
;; feed the parser
(set-buffer mybuf)
(setq parser-result (funcall parser
mybuf stderr-buf status-buf
rc parserdata))
(mc-gpg-debug-print (format " parser returned %s" parser-result))
;; what did the parser tell us?
(if (car parser-result)
;; yes, replace region
(progn
(set-buffer obuf)
(delete-region beg end)
(goto-char beg)
(insert-buffer-substring mybuf)
))
;; return result
(cdr parser-result)
)
;; cleanup forms
(if (and proc (eq 'run (process-status proc)))
;; it is still running. kill it.
(interrupt-process proc))
(set-buffer obuf)
(delete-file stderr-tempfilename)
(delete-file status-tempfilename)
;; kill off temporary buffers unless we're debugging
(if (or (not (boundp 'mc-gpg-debug-buffer))
(not mc-gpg-debug-buffer))
(progn
(if (get-buffer " *mailcrypt stdout temp")
(kill-buffer " *mailcrypt stdout temp"))
(if (get-buffer " *mailcrypt stderr temp")
(kill-buffer " *mailcrypt stderr temp"))
(if (get-buffer " *mailcrypt status temp")
(kill-buffer " *mailcrypt status temp"))
))
)))
; this lookup is used to turn key identifiers into names suitable for
; presentation to the user. When decrypting, the hex keyid to which the
; incoming message is encrypted is looked up to ask the user for a passphrase
; by name. When encrypting, the user's id (mc-gpg-user-id) is looked up to
; ask for a passphrase, and if mc-gpg-encrypt-to-me is true, the user's id
; is looked up to provide a full name to gpg. gpg is always given full names,
; because the hex keyids it provides might not work for both signing and
; encryption (split keys in gpg/pgp5)
;
;31:warner@zs2-pc4% gpg --list-secret-keys --with-colons --no-greeting
;/home/warner/.gnupg/secring.gpg
;-------------------------------
;sec::1024:17:1FE9CBFDC63B6750:1998-08-04:0:::Brian Warner (temporary GPG key) <warner@lothar.com>:
;ssb::1024:20:C68E8DE9F759FBDE:1998-08-04:0:::
;sec::768:17:16BD446D567E33CF:1998-08-04:0:::signature (sample signature key) <key@key>:
;sec::768:16:D514CB72B37D9AF4:1998-08-04:0:::crypt (crypt) <crypt@crypt>:
;sec::1024:17:4DBDD3258230A3E0:1998-08-04:0:::dummyy <d@d>:
;ssb::1024:20:549B0E6CBBBB43D1:1998-08-04:0:::
;
; we use the whole user id string (Brian..lothar.com>) as USER-ID, and the
; long keyid 1FE9CBFDC63B6750 for KEY-ID
(defvar mc-gpg-key-cache nil
"Association list mapping GPG IDs to canonical \"keys\". A \"key\"
is a pair (USER-ID . KEY-ID) which identifies the canonical IDs of the
GPG ID.")
(defun mc-gpg-lookup-key (str &optional type)
;; Look up the string STR in the user's secret key ring. Return a
;; pair of strings (USER-ID . KEY-ID) which uniquely identifies the
;; matching key, or nil if no key matches.
(let (args)
(if (string= str "***** CONVENTIONAL *****") nil
(let ((result (cdr-safe (assoc str mc-gpg-key-cache)))
(key-regexp
"^\\(sec\\|pub\\):[^:]*:[^:]*:[^:]*:\\([^:]*\\):[^:]*:[^:]*:[^:]*:[^:]*:\\([^:]*\\):"
)
(obuf (current-buffer))
buffer)
(if (null result)
(unwind-protect
(progn
(setq buffer (generate-new-buffer " *mailcrypt temp"))
(setq args (list
"--with-colons"
"--no-greeting" "--batch"
"--list-secret-keys" str
))
(if mc-gpg-alternate-keyring
(setq args (append (list "--keyring"
mc-gpg-alternate-keyring)
args)))
(if mc-gpg-extra-args
(setq args (append mc-gpg-extra-args args)))
(mc-gpg-debug-print
(format "lookup: args are %s" args))
(let ((coding-system-for-read
(if (and (fboundp 'coding-system-p)
(coding-system-p 'utf-8))
'utf-8 nil)))
(apply 'call-process mc-gpg-path nil buffer nil args))
(set-buffer buffer)
(goto-char (point-min))
(if (re-search-forward key-regexp nil t)
(progn
(setq result
(cons (buffer-substring-no-properties
(match-beginning 3) (match-end 3))
(concat
"0x"
(buffer-substring-no-properties
(match-beginning 2) (match-end 2)))))
(setq mc-gpg-key-cache (cons (cons str result)
mc-gpg-key-cache)))))
;(if buffer (kill-buffer buffer))
(set-buffer obuf)))
(if (null result)
(error "No GPG secret key for %s" str))
result))))
;gpg: no info to calculate a trust probability
;gpg: no valid addressees
;gpg: [stdin]: encryption failed: No such user id
(defun mc-gpg-encrypt-region (recipients start end &optional id sign)
(let ((process-environment process-environment)
(buffer (get-buffer-create mc-buffer-name))
(obuf (current-buffer))
action msg args key passwd result gpg-id)
(mc-gpg-debug-print (format
"(mc-gpg-encrypt-region recipients=%s start=%s end=%s id=%s sign=%s)"
recipients start end id sign))
(setq args (list
"--batch" "--armor" "--textmode" "--always-trust"
(if recipients "--encrypt" "--store")
))
(setq action (if recipients "Encrypting" "Armoring"))
(setq msg (format "%s..." action)) ; May get overridden below
(if mc-gpg-comment
(setq args (append (list "--comment" (format "'%s'" mc-gpg-comment))
args)))
(if mc-gpg-alternate-keyring
(setq args (append (list "--keyring" mc-gpg-alternate-keyring) args)))
(if (and (not (eq mc-pgp-always-sign 'never))
(or mc-pgp-always-sign sign (y-or-n-p "Sign the message? ")))
(progn
(setq key (mc-gpg-lookup-key (or id mc-gpg-user-id) 'encrypt))
(setq passwd
(mc-activate-passwd
(cdr key)
(format "GPG passphrase for %s (%s): " (car key) (cdr key))))
(setq args
(append (list "--local-user" (cdr key)
"--sign"
)
args))
(setq msg (format "%s+signing as %s ..." action (car key)))
(if (not recipients)
;; the --store is last in args. remove it. remove --textmode too
(setq args (nreverse (cddr (nreverse args)))))
)
)
; if we're supposed to encrypt for the user too, we need their key
;; FIXME: we only need their public key, not the secret one. Some users
;; (the author included) keep their secret keys offline unless needed
;; (but the public ones are still available).. the --list-secret-keys
;; done by mc-gpg-lookup-key will fail in this situation. Change
;; mc-gpg-lookup-key to have a way to look for public keys too.
(if (and recipients mc-encrypt-for-me)
(setq recipients (cons (cdr (or key
(setq key (mc-gpg-lookup-key
mc-gpg-user-id 'encrypt)))
) recipients)))
; push(@args, map {qq<-r "$_">} @recipients) if @recipients; # roughly
(if recipients
(setq args (append (apply 'append
(mapcar '(lambda (x)
(list "--recipient"
(concat "\"" x "\"")))
recipients))
args)))
(message "%s" msg)
(setq result (mc-gpg-process-region start end passwd mc-gpg-path args
'mc-gpg-insert-parser buffer))
(if (not (car result))
(error "%s failed: %s" msg (nth 2 result)))
t
))
; GPG DECRYPT BEHAVIOR: gnupg-0.9.9 only
; (all status messages are prefixed by "[GNUPG:] "
; signed (not encrypted) by a known key [S.s1v]:
; rc == 0, stdout has message
; status:
; SIG_ID <sigid> <date> <longtime>
; GOODSIG <longkeyid> <username>
; VALIDSIG <keyfingerprint> <date> <longtime>
; TRUST_foo
; signed (not encrypted) by unknown key [S.s4]:
; rc == 2, stdout has message
; status:
; ERRSIG <longkeyid> <pubkeyalgo> <hashalgo> <sigclass> <longtime> <rc>
; NO_PUBKEY <longkeyid>
; encrypted to a private key we don't have [E.e3]:
; rc == 2,
; stderr: gpg: decryption failed: secret key not available
; status:
; ENC_TO <longkeyid> <keytype> <keylength==0>
; NO_SECKEY <longkeyid>
; DECRYPTION_FAILED
; encrypted to us, our key has no passphrase
; rc == 0?
; stderr: gpg: NOTE: secret key foo is NOT protected
; status:
; ENC_TO <longkeyid> <keytype> <keylen==0>
; GOOD_PASSPHRASE
; DECRYPTION_OKAY
; encrypted to us, but we didn't give a passphrase [E.e1r, no pw]:
; rc == 2
; stderr: gpg: fatal: Can't query password in batchmode
; status:
; ENC_TO <longkeyid> <keytype> <keylength==0>
; NEED_PASSPHRASE <longkeyid> <otherlongkeyid> <keytype> <keylen==0>
; MISSSING_PASSPHRASE
; BAD_PASSPHRASE <longkeyid>
; DECRYPTION_FAILED
; (N.B.: gpg cannot tell tell the difference between no passphrase and an
; empty passphrase.)
; encrypted to us *and someone else*, no passphrase [E.e3re1r, no pw]:
; rc == 2?
; stderr: gpg: fatal: Can't query password in batchmode
; status:
; ENC_TO <longkeyid1> <keytype> <keylength==0>
; NEED_PASSPHRASE <longkeyid1> <otherlongkeyid> <keytype> <keylen==0>
; MISSSING_PASSPHRASE
; BAD_PASSPHRASE <longkeyid1>
; ENC_TO <longkeyid2> .. ..
; NO_SECKEY <longkeyid2>
; DECRYPTION_FAILED
; encrypted to us, but we used the wrong passphrase [E.e1r, bad pw]:
; rc == 2
; stderr: gpg: public key decryption failed: [Bb]ad passphrase
; status:
; ENC_TO <longkeyid> <keytype> <keylength==0>
; NEED_PASSPHRASE <longkeyid> <otherlongkeyid> <keytype> <keylen==0>
; BAD_PASSPHRASE <longkeyid>
; DECRYPTION_FAILED
; encrypted to us, good passphrase [E.e1r, good pw]:
; rc == 0, stdout has message
; status:
; ENC_TO <longkeyid> <keytype> <keylength==0>
; NEED_PASSPHRASE <longkeyid> <otherlongkeyid> <keytype> <keylen==0>
; GOOD_PASSPHRASE
; DECRYPTION_OKAY
; encrypted to us, good passphrase, signed by trusted/untrusted party
; [ES.e1r.s1v, good ps]:
; rc == 0, stdout has message
; stderr: gpg: Signature made <date> using DSA key ID <pubkeyid>
; stderr: gpg: Good signature from "<keyname>"
; status:
; ENC_TO <longkeyid> <keytype> <keylength==0>
; NEED_PASSPHRASE <longkeyid> <otherlongkeyid> <keytype> <keylen==0>
; GOOD_PASSPHRASE
; SIG_ID <sigid> <date> <longtime>
; GOODSIG <longkeyid> <username>
; VALIDSIG <keyfingerprint> <date> <longtime>
; TRUST_(UNDEFINED|NEVER|MARGINAL|FULLY|ULTIMATE)
; DECRYPTION_OKAY
; encrypted to us, good passphrase, signed by unknown party [ES.e1r.s4]:
; rc == 2, stdout has message
; stderr: gpg: Signature made <date> using DSA key ID <pubkeyid>
; stderr: gpg: Can't check signature: [Pp]ublic key not found
; status:
; ENC_TO <longkeyid> <keytype> <keylength==0>
; NEED_PASSPHRASE <longkeyid> <otherlongkeyid> <keytype> <keylen==0>
; GOOD_PASSPHRASE
; ERRSIG <longkeyid> <pubkeyalgo> <hashalgo> <sigclass> <longtime> <rc>
; rc: 4 is unknown algorithm, 9 is missing public key
; NO_PUBKEY <longkeyid>
; DECRYPTION_OKAY
; symmetrically encrypted, we didn't give a passphrase
; rc == 2, stderr: gpg: fatal: Can't query password in batchmode
; status:
; NEED_PASSPHRASE_SYM <cipheralgo> <s2kmode> <s2khash>
; MISSING_PASSPHRASE
; DECRYPTION_FAILED
; symmetrically encrypted, we gave the wrong passphrase
; rc == 2, stderr: gpg: decryption failed: [Bb]ad key
; status:
; NEED_PASSPHRASE_SYM <cipheralgo> <s2kmode> <s2khash>
; DECRYPTION_FAILED
; symmetrically encrypted, good passphrase
; rc == 0, stdout: message
; status:
; NEED_PASSPHRASE_SYM <cipheralgo> <s2kmode> <s2khash>
; DECRYPTION_OKAY
; armored [A]:
; rc == 0, stdout: message
; no status
; corrupted armor
; rc == 2, stderr: gpg: CRC error; stuff - stuff
; ( to test: multiple recipients, keys without passphrases)
;; this parser's return convention:
;; '( (
;; replacep ; consumed by process-region: decrypt was successful
;;0 have-secret-key ; t: we are a recipient (TODO: stealth),
;; 'symmetric : need passphrase
;; 'signed : signed not encrypted
;; nil: not a recipient
;;1 passphrase-ok ; t was good, nil was bad, keyid: need pw for keyid
;;2 signature:
;; nil: no sig
;; keyid-hex : don't have signature key
;; '(keyid-string t trust date) : good signature on date with trust
;; '(keyid-string nil trust date) : bad signature on date with trust
;; )
;; )
; todo: stealth ("--throw-keyid")?
; when there is a signature that we can't check because of a bad algo
; then we pretend there wasn't a signature. extend the return convention
; to signal this case.
; when there is a signature that we can't check because we don't
; currently have a key, and if we successfully fetch that key in
; mc-gpg-decrypt-region, how do we restart the operation?
;; cases:
;; *not addressed to us (nil nil nil)
;; *just armored (same as good symmetric) ('symmetric t nil)
;; conventionally encrypted
;; *didn't give passphrase ('symmetric "***** CONVENTIONAL *****" nil)
;; did give passphrase
;; *bad passphrase ('symmetric nil nil)
;; *good passphrase ('symmetric t nil)
;; signed (not clearsigned), not encrypted
;; *don't have key ('signed t keyid)
;; do have key
;; *good sig ('signed t (t keyid-string trust date))
;; *bad sig ('signed t (nil keyid-string trust date))
;; encrypted to us:
;; *didn't give passphrase (t keyid nil)
;; gave passphrase:
;; *bad passphrase (t nil nil)
;; good passphrase
;; decrypted ok
;; *no signature (t t nil)
;; yes signature
;; *don't have key (offer to fetch) (t t keyid)
;; do have key
;; *good sig (t t (t keyid-string date trust))
;; *bad sig (t t (nil keyid-string date trust))
;; a subfunction to extract the signature info. Used in both decrypt-parser
;; and verify-parser. Call with statusbuf. Returns
;; '(sigtype sigid sigdate sigtrust)
(defun mc-gpg-sigstatus-parser ()
(let (sigtype sigid sigdate sigtrust)
;; sigtype: GOOD, BAD, ERR
;; sigid: who made the signature? (a name if possible, else hex keyid)
;; sigdate: date string of when the sig was made
(goto-char (point-min))
(if (re-search-forward "^\\[GNUPG:\\] +\\(GOOD\\|BAD\\|ERR\\)SIG\\b"
nil t)
(progn
(setq sigtype (match-string 1))
(goto-char (point-min))
(if (and (or (string= sigtype "GOOD") (string= sigtype "BAD"))
(re-search-forward
"^\\[GNUPG:\\] +\\(GOOD\\|BAD\\)SIG +\\(\\S +\\) +\\(.*\\)$" nil t))
;; match-string 2 is the hex keyid of the signator.
;; #3 is the name
(setq sigid (match-string 3)))
;; for ERRSIG:
;; match-string #1 is the hex keyid, #2 is the algorithm ID
;; (17: DSA, 1,3: RSA, 20: Elgamal)
;; #3: hashalgo, #4: sigclass, #5: longtime, #6: rc
;; (rc==4 for unknown algo, 9 for missing public key)
;; we only set sigtype if:
;; (#1 is present), and
;; ((#6 is missing) or (#6 == 9))
;; the idea being to not fetch a key if we aren't going to be able
;; to use the algorithm it wants
(goto-char (point-min))
(if (and (string= sigtype "ERR")
(re-search-forward
"^\\[GNUPG:\\] +ERRSIG +\\(\\S +\\)" nil t))
(let (errsig-rc (sigid-temp (match-string 1)))
(goto-char (point-min))
(if (re-search-forward
"^\\[GNUPG:\\] +ERRSIG +\\(\\S +\\) +\\(\\S +\\) +\\(\\S +\\) +\\(\\S +\\) +\\(\\S +\\) +\\(\\S +\\)" nil t)
(setq errsig-rc (match-string 6)))
(if (or
(not errsig-rc)
(string= errsig-rc "9"))
(setq sigid sigid-temp))
))
;; for GOODSIG:
;; VALIDSIG should be present, with <keyfingerprint> <date> <time>
(goto-char (point-min))
(if (and (string= sigtype "GOOD")
(re-search-forward
"^\\[GNUPG:\\] +SIG_ID +\\(\\S +\\) +\\(\\S +\\)\\b"
nil t))
(setq sigdate (match-string 2))
;; in gpg >= 0.9.7, a third field is a longtime value (seconds
;; since epoch)
)
;; sigtrust: how trusted is the signing key?
(goto-char (point-min))
(if (re-search-forward "^\\[GNUPG:\\] +\\(TRUST_\\S +\\)$" nil t)
(setq sigtrust (match-string 1)))
))
(list sigtype sigid sigdate sigtrust))
)
; this parser's job is to find the decrypted data if any is available. The
; code in -decrypt-region will worry about reporting other status information
; like signatures. PARSERDATA is non-nil if a passphrase was given to GPG.
(defun mc-gpg-decrypt-parser (stdoutbuf stderrbuf statusbuf rc parserdata)
(let
(
decryptstatus ; DECRYPTION_(OKAY|FAILED)
no-seckey ; NO_SECKEY
keyid ; NEED_PASSPHRASE <keyid>
missing-passphrase ; MISSING_PASSPHRASE
symmetric ; NEED_PASSPHRASE_SYM
badpass ; BAD_PASSPHRASE
sigtype ; GOODSIG, BADSIG, ERRSIG
sigid ;; GOODSIG <keyid> (note: not SIG_ID!),
;;; or ERRSIG <keyid> if ERRSIG-rc is 9 for missing pubkey
sigdate ; VALIDSIG .. <date>
sigtrust ; TRUST_(UNDEFINED|NEVER|MARGINAL|FULLY|ULTIMATE)
)
;; this code is split into two pieces. The first scans statusbuf
;; (and stderr if absolutely necessary) for keywords, setting the
;; local variables to describe what happened during our decryption attempt.
;; We don't try too hard to interpret the results yet.
;; the second part (the big cond statement below) interprets those vars
;; to decide what to report to the caller
(set-buffer statusbuf)
;; decryptstatus: no decryption took place, one was ok, or one failed
(goto-char (point-min))
(if (re-search-forward
"^\\[GNUPG:\\] +DECRYPTION_\\(OKAY\\|FAILED\\)\\b"
nil t)
(setq decryptstatus (match-string 1)))
;; no-seckey: set if we saw a NO_SECKEY message.
(goto-char (point-min))
(if (re-search-forward
"^\\[GNUPG:\\] +NO_SECKEY\\b"
nil t)
(setq no-seckey t))
;; keyid: the message is encrypted to one of our private keys and we
;; need a passphrase from the user. which one?
(goto-char (point-min))
(if (re-search-forward "^\\[GNUPG:\\] +NEED_PASSPHRASE +\\(\\S +\\)"
nil t)
(setq keyid (concat "0x" (match-string 1))))
;; missing-passphrase: set if we saw MISSING_PASSPHRASE
(goto-char (point-min))
(if (re-search-forward "^\\[GNUPG:\\] +MISSING_PASSPHRASE\\b"
nil t)
(setq missing-passphrase t))
;; symmetric: Set if the message is symmetrically encrypted.
(goto-char (point-min))
(if (re-search-forward
"^\\[GNUPG:\\] +NEED_PASSPHRASE_SYM\\b"
nil t)
(setq symmetric t))
;; badpass: GPG did not get a good passphrase. Either we didn't give one
;; or we gave the wrong one.
(goto-char (point-min))
(if (re-search-forward "^\\[GNUPG:\\] +BAD_PASSPHRASE\\b"
nil t)
(setq badpass t))
(let ((sigstuff (mc-gpg-sigstatus-parser)))
(setq sigtype (nth 0 sigstuff))
(setq sigid (nth 1 sigstuff))
(setq sigdate (nth 2 sigstuff))
(setq sigtrust (nth 3 sigstuff))
)
;; begin second piece: stare at those variables and decide what happened.
;; refer to the "cases:" comment above for what we look for.
(mc-gpg-debug-print
(format
"decrypt-parser: decryptstatus=%s no-seckey=%s keyid=%s missing-passphrase=%s symmetric=%s badpass=%s sigtype=%s sigid=%s sigdate=%s sigtrust=%s rc=%s"
decryptstatus no-seckey keyid missing-passphrase symmetric badpass sigtype sigid sigdate sigtrust rc))
(cond
((and (not decryptstatus) (not (or keyid symmetric)))
;; either corrupt, armored-only, signed-only
;; or we're using an old gpg and no passphrase was requested:
;; either corrupt, armored-only, signed-only, or not for us.
(cond
(sigtype
;; signed-only. extract info
(cond
((string= sigtype "GOOD") ;; good signature
(list t 'signed t (list t sigid sigtrust sigdate)))
((string= sigtype "BAD") ;; bad signature
(list t 'signed t (list nil sigid sigtrust sigdate)))
((string= sigtype "ERR") ;; couldn't check: why?
(if sigid
;; didn't have the key, we can fetch it
(list t 'signed t sigid)
;; can't use it. pretend it wasn't signed.
(list t t t nil)))
(t ;; sigtype is bogus
(error "sigtype was bogus. Shouldn't happen."))
))
((not (= rc 0)) ;; corrupt
(error "The message was corrupt."))
(t ;; armored-only
(list t 'symmetric t nil))
))
((or
(string= decryptstatus "FAILED")
;; couldn't decrypt: not to us, need pw, bad pw
(and (not decryptstatus)
(or keyid symmetric)
(not (= rc 0))
(not (string= sigtype "ERR")))
;; or old gpg and we could have decrypted it (a passphrase was
;; requested), but the decrypt went bad (rc!=0 but not due to ERRSIG)
)
(cond
((and (not symmetric) (not keyid))
;; didn't ask for a passphrase, ergo it isn't for us
(list nil nil nil nil))
((or missing-passphrase (not parserdata))
;; we didn't give a passphrase, need pubkey or symmetric
(if symmetric
(list nil 'symmetric "***** CONVENTIONAL *****" nil)
(list nil t keyid nil)))
(symmetric ;; symmetric fails without a BAD_PASSPHRASE
(list nil 'symmetric nil nil))
((or badpass parserdata)
;; probably pubkey, we gave the wrong passphrase
(list nil t nil nil))
(t ;; shouldn't happen, error out
(error "decryption failed, but I don't know why. Shouldn't happen."))
))
((or
(string= decryptstatus "OKAY")
;; decrypted okay, check for signature
(and (not decryptstatus)
keyid
(not (= rc 0))
(string= sigtype "ERR"))
;; or old gpg and sigcheck went bad (rc!=0 due to ERRSIG)
(and (not decryptstatus)
keyid
(= rc 0))
;; or old gpg, passphrase was requested, no errors reported
)
(cond
(sigtype ;; there was a signature, extract the info (never sym here)
(cond
((string= sigtype "GOOD") ;; good signature
(list t t t (list t sigid sigtrust sigdate)))
((string= sigtype "BAD") ;; bad signature
(list t t t (list nil sigid sigtrust sigdate)))
((string= sigtype "ERR") ;; couldn't check: why?
(if sigid
;; didn't have the key. we can fetch it.
(list t t t sigid)
;; no keyid, or we can't use it. pretend there wasn't a sig.
(list t t t nil)))
(t ;; sigtype is bogus
(error "sigtype was bogus. Shouldn't happen."))
))
(t ;; there wasn't a signature
(if symmetric
(list t 'symmetric t nil)
(list t t t nil)))
))
(t ;; decryptstatus was bogus. error out.
(error "decryptstatus was bogus '%s'. Shouldn't happen." decryptstatus))
)
))
;; message about who made the signature. This is a bit wide.. the date can
;; easily run off the echo area. Consider replacing 'Good signature' with
;; 'good sig', but keep it consistent with everything else. This function is
;; used by both the decrypt section and the verify section.
;; todo: should the keyid be put in here? If the user reads the trustvalue,
;; and if they have a trust path, then they can trust the name.
(defun mc-gpg-format-sigline (goodp sigid sigtrust sigdate)
(if goodp
(format "Good signature from '%s' %s made %s"
sigid sigtrust sigdate)
(format "BAD SIGNATURE claiming to be from '%s'" sigid)
))
;; decrypt-region is first called without ID. This means we'll try to decrypt
;; without a passphrase, almost guaranteed to fail, but it will tell us which
;; key is necessary. We then call decrypt-region again, this time with ID
;; set. This second time will lookup ID and ask the user for the passphrase.
(defun mc-gpg-decrypt-region (start end &optional id)
;; returns a pair (SUCCEEDED . VERIFIED) where SUCCEEDED is t if
;; the decryption succeeded and verified is t if there was a valid signature
(let ((process-environment process-environment)
(buffer (get-buffer-create mc-buffer-name))
(obuf (current-buffer))
args key new-key passwd result gpg-id)
(mc-gpg-debug-print (format "(mc-gpg-decrypt-region start=%s end=%s id=%s)"
start end id))
(undo-boundary)
(if id
;; second time through, now we know who the message is for.
;; id is either a hex keyid of the (first?) secret key that is in
;; the message's recipient list, or "**..CONVENTIONAL.."
(progn
(setq key (mc-gpg-lookup-key id 'encrypt))
;; key is nil if CONVENTIONAL, (string . hexid) otherwise
(setq passwd
(if key
(mc-activate-passwd (cdr key)
(format
"GPG passphrase for %s (%s): "
(car key) (cdr key)))
(mc-activate-passwd
id "GPG passphrase for conventional decryption: ")))
(if (string= passwd "")
(progn
(mc-deactivate-passwd t)
(error "Empty passphrases are bad, mmkay?")))
;; in particular, they cause an infinite loop. If the key doesn't
;; have a passphrase, the decryption should have worked the first
;; time around.
))
(setq args '("--batch"))
(if mc-gpg-alternate-keyring
(setq args (append args (list "--keyring" mc-gpg-alternate-keyring))))
(setq args (append args '("--decrypt"))) ; this wants to be last
(message "Decrypting...")
;; pass ID as the parserdata. This will be non-nil if a passphrase was
;; given (i.e. 2nd pass), which affects decrypt status parsing
(setq result
(mc-gpg-process-region
start end passwd mc-gpg-path args 'mc-gpg-decrypt-parser buffer id))
;(message "Decrypting... Done.")
;; result: '(HAVE-SECRET-KEY PASSPHRASE-OK SIG)
;; SIG: nil, sigkeyid, or '(KEYID GOODP TRUSTLEVEL DATESTRING)
(cond
((not (nth 0 result)) ;; we were not a recipient
(error "This message is not addressed to you"))
((not (nth 1 result)) ;; passphrase-ok is nil: bad passphrase
(mc-deactivate-passwd t)
(error "That passphrase was wrong"))
((not (equal (nth 1 result) t)) ;; passphrase-ok is keyid: need passphrase
;; get passphrase for (nth 1 result), try again
(mc-gpg-decrypt-region start end (nth 1 result))
)
;; passphrase was ok, were able to decrypt
((nth 2 result) ;; there was a signature
(let ((sig (nth 2 result)))
(cond
((atom sig) ;; don't have the signature key
(progn
;; offer to fetch the key, then what? run again? must we undo 1st?
(mc-message-sigstatus
(format "cannot check signature from keyid %s" sig))
(if (and (not (eq mc-gpg-always-fetch 'never))
(or mc-gpg-always-fetch
(y-or-n-p
(format "Key %s not found; attempt to fetch? " sig)))
(mc-gpg-fetch-key (cons nil sig)))
(progn
(undo-start)
(undo-more 1)
(mc-gpg-decrypt-region start end id))
'(t . nil))
))
((nth 0 sig) ;; good signature
(progn
(mc-message-sigstatus (mc-gpg-format-sigline
t (nth 1 sig) (nth 2 sig) (nth 3 sig)))
'(t . t)
))
(t ;; bad signature
(progn
(mc-message-sigstatus (mc-gpg-format-sigline
nil (nth 1 sig) (nth 2 sig) (nth 3 sig))
t ; get their attention
)