1 @c Copyright (C) 2002 Free Software Foundation, Inc.
2 @c This is part of the GnuPG manual.
3 @c For copying conditions, see the file gnupg.texi.
7 @node Invoking GPG-AGENT
8 @chapter Invoking GPG-AGENT
9 @cindex GPG-AGENT command options
10 @cindex command options
11 @cindex options, GPG-AGENT command
16 \- Secret key management for GnuPG
47 @command{gpg-agent} is a daemon to manage secret (private) keys
48 independently from any protocol. It is used as a backend for
49 @command{gpg} and @command{gpgsm} as well as for a couple of other
52 The agent is automatically started on demand by @command{gpg},
53 @command{gpgsm}, @command{gpgconf}, or @command{gpg-connect-agent}.
54 Thus there is no reason to start it manually. In case you want to use
55 the included Secure Shell Agent you may start the agent using:
58 gpg-connect-agent /bye
62 You should always add the following lines to your @code{.bashrc} or
63 whatever initialization file is used for all shell invocations:
71 It is important that this environment variable always reflects the
72 output of the @code{tty} command. For W32 systems this option is not
75 Please make sure that a proper pinentry program has been installed
76 under the default filename (which is system dependent) or use the
77 option @option{pinentry-program} to specify the full name of that program.
78 It is often useful to install a symbolic link from the actual used
79 pinentry (e.g. @file{@value{BINDIR}/pinentry-gtk}) to the expected
80 one (e.g. @file{@value{BINDIR}/pinentry}).
84 @xref{Option Index},for an index to @command{GPG-AGENT}'s commands and options.
88 * Agent Commands:: List of all commands.
89 * Agent Options:: List of all options.
90 * Agent Configuration:: Configuration files.
91 * Agent Signals:: Use of some signals.
92 * Agent Examples:: Some usage examples.
93 * Agent Protocol:: The protocol the agent uses.
100 Commands are not distinguished from options except for the fact that
101 only one command is allowed.
106 Print the program version and licensing information. Note that you cannot
107 abbreviate this command.
112 Print a usage message summarizing the most useful command-line options.
113 Note that you cannot abbreviate this command.
116 @opindex dump-options
117 Print a list of all available options and commands. Note that you cannot
118 abbreviate this command.
122 Run in server mode and wait for commands on the @code{stdin}. The
123 default mode is to create a socket and listen for commands there.
125 @item --daemon [@var{command line}]
127 Start the gpg-agent as a daemon; that is, detach it from the console
128 and run it in the background.
130 As an alternative you may create a new process as a child of
131 gpg-agent: @code{gpg-agent --daemon /bin/sh}. This way you get a new
132 shell with the environment setup properly; after you exit from this
133 shell, gpg-agent terminates within a few seconds.
138 @section Option Summary
142 @anchor{option --options}
143 @item --options @var{file}
145 Reads configuration from @var{file} instead of from the default
146 per-user configuration file. The default configuration file is named
147 @file{gpg-agent.conf} and expected in the @file{.gnupg} directory directly
148 below the home directory of the user.
150 @anchor{option --homedir}
151 @include opt-homedir.texi
157 Outputs additional information while running.
158 You can increase the verbosity by giving several
159 verbose commands to @command{gpgsm}, such as @samp{-vv}.
164 Try to be as quiet as possible.
168 Don't invoke a pinentry or do any other thing requiring human interaction.
170 @item --faked-system-time @var{epoch}
171 @opindex faked-system-time
172 This option is only useful for testing; it sets the system time back or
173 forth to @var{epoch} which is the number of seconds elapsed since the year
176 @item --debug-level @var{level}
178 Select the debug level for investigating problems. @var{level} may be
179 a numeric value or a keyword:
183 No debugging at all. A value of less than 1 may be used instead of
186 Some basic debug messages. A value between 1 and 2 may be used
187 instead of the keyword.
189 More verbose debug messages. A value between 3 and 5 may be used
190 instead of the keyword.
192 Even more detailed messages. A value between 6 and 8 may be used
193 instead of the keyword.
195 All of the debug messages you can get. A value greater than 8 may be
196 used instead of the keyword. The creation of hash tracing files is
197 only enabled if the keyword is used.
200 How these messages are mapped to the actual debugging flags is not
201 specified and may change with newer releases of this program. They are
202 however carefully selected to best aid in debugging.
204 @item --debug @var{flags}
206 This option is only useful for debugging and the behaviour may change at
207 any time without notice. FLAGS are bit encoded and may be given in
208 usual C-Syntax. The currently defined bits are:
212 X.509 or OpenPGP protocol related data
214 values of big number integers
216 low level crypto operations
222 show memory statistics.
224 write hashed data to files named @code{dbgmd-000*}
226 trace Assuan protocol
228 bypass all certificate validation
233 Same as @code{--debug=0xffffffff}
235 @item --debug-wait @var{n}
237 When running in server mode, wait @var{n} seconds before entering the
238 actual processing loop and print the pid. This gives time to attach a
241 @item --debug-quick-random
242 @opindex debug-quick-random
243 This option inhibits the use of the very secure random quality level
244 (Libgcrypt’s @code{GCRY_VERY_STRONG_RANDOM}) and degrades all request
245 down to standard random quality. It is only used for testing and
246 shall not be used for any production quality keys. This option is
247 only effective when given on the command line.
249 @item --debug-pinentry
250 @opindex debug-pinentry
251 This option enables extra debug information pertaining to the
252 Pinentry. As of now it is only useful when used along with
257 Don't detach the process from the console. This is mainly useful for
266 Format the info output in daemon mode for use with the standard Bourne
267 shell or the C-shell respectively. The default is to guess it based on
268 the environment variable @code{SHELL} which is correct in almost all
274 Tell the pinentry not to grab the keyboard and mouse. This option
275 should in general not be used to avoid X-sniffing attacks.
277 @anchor{option --log-file}
278 @item --log-file @var{file}
280 Append all logging output to @var{file}. This is very helpful in seeing
281 what the agent actually does. If neither a log file nor a log file
282 descriptor has been set on a Windows platform, the Registry entry
283 @code{HKCU\Software\GNU\GnuPG:DefaultLogFile}, if set, is used to specify
287 @anchor{option --no-allow-mark-trusted}
288 @item --no-allow-mark-trusted
289 @opindex no-allow-mark-trusted
290 Do not allow clients to mark keys as trusted, i.e. put them into the
291 @file{trustlist.txt} file. This makes it harder for users to inadvertently
294 @anchor{option --allow-preset-passphrase}
295 @item --allow-preset-passphrase
296 @opindex allow-preset-passphrase
297 This option allows the use of @command{gpg-preset-passphrase} to seed the
298 internal cache of @command{gpg-agent} with passphrases.
300 @anchor{option --allow-loopback-pinentry}
301 @item --allow-loopback-pinentry
302 @opindex allow-loopback-pinentry
303 Allow clients to use the loopback pinentry features; see the option
304 @option{pinentry-mode} for details.
306 @item --no-allow-external-cache
307 @opindex no-allow-external-cache
308 Tell Pinentry not to enable features which use an external cache for
311 Some desktop environments prefer to unlock all
312 credentials with one master password and may have installed a Pinentry
313 which employs an additional external cache to implement such a policy.
314 By using this option the Pinentry is advised not to make use of such a
315 cache and instead always ask the user for the requested passphrase.
317 @item --allow-emacs-pinentry
318 @opindex allow-emacs-pinentry
319 Tell Pinentry to allow features to divert the passphrase entry to a
320 running Emacs instance. How this is exactly handled depends on the
321 version of the used Pinentry.
323 @item --ignore-cache-for-signing
324 @opindex ignore-cache-for-signing
325 This option will let @command{gpg-agent} bypass the passphrase cache for all
326 signing operation. Note that there is also a per-session option to
327 control this behaviour but this command line option takes precedence.
329 @item --default-cache-ttl @var{n}
330 @opindex default-cache-ttl
331 Set the time a cache entry is valid to @var{n} seconds. The default is
334 @item --default-cache-ttl-ssh @var{n}
335 @opindex default-cache-ttl
336 Set the time a cache entry used for SSH keys is valid to @var{n}
337 seconds. The default is 1800 seconds.
339 @item --max-cache-ttl @var{n}
340 @opindex max-cache-ttl
341 Set the maximum time a cache entry is valid to @var{n} seconds. After
342 this time a cache entry will be expired even if it has been accessed
343 recently or has been set using @command{gpg-preset-passphrase}. The
344 default is 2 hours (7200 seconds).
346 @item --max-cache-ttl-ssh @var{n}
347 @opindex max-cache-ttl-ssh
348 Set the maximum time a cache entry used for SSH keys is valid to
349 @var{n} seconds. After this time a cache entry will be expired even
350 if it has been accessed recently or has been set using
351 @command{gpg-preset-passphrase}. The default is 2 hours (7200
354 @item --enforce-passphrase-constraints
355 @opindex enforce-passphrase-constraints
356 Enforce the passphrase constraints by not allowing the user to bypass
357 them using the ``Take it anyway'' button.
359 @item --min-passphrase-len @var{n}
360 @opindex min-passphrase-len
361 Set the minimal length of a passphrase. When entering a new passphrase
362 shorter than this value a warning will be displayed. Defaults to 8.
364 @item --min-passphrase-nonalpha @var{n}
365 @opindex min-passphrase-nonalpha
366 Set the minimal number of digits or special characters required in a
367 passphrase. When entering a new passphrase with less than this number
368 of digits or special characters a warning will be displayed. Defaults
371 @item --check-passphrase-pattern @var{file}
372 @opindex check-passphrase-pattern
373 Check the passphrase against the pattern given in @var{file}. When
374 entering a new passphrase matching one of these pattern a warning will
375 be displayed. @var{file} should be an absolute filename. The default is
376 not to use any pattern file.
378 Security note: It is known that checking a passphrase against a list of
379 pattern or even against a complete dictionary is not very effective to
380 enforce good passphrases. Users will soon figure up ways to bypass such
381 a policy. A better policy is to educate users on good security
382 behavior and optionally to run a passphrase cracker regularly on all
383 users passphrases to catch the very simple ones.
385 @item --max-passphrase-days @var{n}
386 @opindex max-passphrase-days
387 Ask the user to change the passphrase if @var{n} days have passed since
388 the last change. With @option{--enforce-passphrase-constraints} set the
389 user may not bypass this check.
391 @item --enable-passphrase-history
392 @opindex enable-passphrase-history
393 This option does nothing yet.
395 @item --pinentry-program @var{filename}
396 @opindex pinentry-program
397 Use program @var{filename} as the PIN entry. The default is
398 installation dependent. With the default configuration the name of
399 the default pinentry is @file{pinentry}; if that file does not exist
400 but a @file{pinentry-basic} exist the latter is used.
402 @item --pinentry-touch-file @var{filename}
403 @opindex pinentry-touch-file
404 By default the filename of the socket gpg-agent is listening for
405 requests is passed to Pinentry, so that it can touch that file before
406 exiting (it does this only in curses mode). This option changes the
407 file passed to Pinentry to @var{filename}. The special name
408 @code{/dev/null} may be used to completely disable this feature. Note
409 that Pinentry will not create that file, it will only change the
410 modification and access time.
413 @item --scdaemon-program @var{filename}
414 @opindex scdaemon-program
415 Use program @var{filename} as the Smartcard daemon. The default is
416 installation dependent and can be shown with the @command{gpgconf}
419 @item --disable-scdaemon
420 @opindex disable-scdaemon
421 Do not make use of the scdaemon tool. This option has the effect of
422 disabling the ability to do smartcard operations. Note, that enabling
423 this option at runtime does not kill an already forked scdaemon.
425 @item --disable-check-own-socket
426 @opindex disable-check-own-socket
427 @command{gpg-agent} employs a periodic self-test to detect a stolen
428 socket. This usually means a second instance of @command{gpg-agent}
429 has taken over the socket and @command{gpg-agent} will then terminate
430 itself. This option may be used to disable this self-test for
433 @item --use-standard-socket
434 @itemx --no-use-standard-socket
435 @itemx --use-standard-socket-p
436 @opindex use-standard-socket
437 @opindex no-use-standard-socket
438 @opindex use-standard-socket-p
439 Since GnuPG 2.1 the standard socket is always used. These options
440 have no more effect. The command @code{gpg-agent
441 --use-standard-socket-p} will thus always return success.
443 @item --display @var{string}
444 @itemx --ttyname @var{string}
445 @itemx --ttytype @var{string}
446 @itemx --lc-ctype @var{string}
447 @itemx --lc-messages @var{string}
448 @itemx --xauthority @var{string}
455 These options are used with the server mode to pass localization
459 @itemx --keep-display
461 @opindex keep-display
462 Ignore requests to change the current @code{tty} or X window system's
463 @code{DISPLAY} variable respectively. This is useful to lock the
464 pinentry to pop up at the @code{tty} or display you started the agent.
467 @anchor{option --extra-socket}
468 @item --extra-socket @var{name}
469 @opindex extra-socket
470 Also listen on native gpg-agent connections on the given socket. The
471 intended use for this extra socket is to setup a Unix domain socket
472 forwarding from a remote machine to this socket on the local machine.
473 A @command{gpg} running on the remote machine may then connect to the
474 local gpg-agent and use its private keys. This allows to decrypt or
475 sign data on a remote machine without exposing the private keys to the
479 @anchor{option --enable-ssh-support}
480 @item --enable-ssh-support
481 @opindex enable-ssh-support
483 Enable the OpenSSH Agent protocol.
485 In this mode of operation, the agent does not only implement the
486 gpg-agent protocol, but also the agent protocol used by OpenSSH
487 (through a separate socket). Consequently, it should be possible to use
488 the gpg-agent as a drop-in replacement for the well known ssh-agent.
490 SSH Keys, which are to be used through the agent, need to be added to
491 the gpg-agent initially through the ssh-add utility. When a key is
492 added, ssh-add will ask for the password of the provided key file and
493 send the unprotected key material to the agent; this causes the
494 gpg-agent to ask for a passphrase, which is to be used for encrypting
495 the newly received key and storing it in a gpg-agent specific
498 Once a key has been added to the gpg-agent this way, the gpg-agent
499 will be ready to use the key.
501 Note: in case the gpg-agent receives a signature request, the user might
502 need to be prompted for a passphrase, which is necessary for decrypting
503 the stored key. Since the ssh-agent protocol does not contain a
504 mechanism for telling the agent on which display/terminal it is running,
505 gpg-agent's ssh-support will use the TTY or X display where gpg-agent
506 has been started. To switch this display to the current one, the
507 following command may be used:
510 gpg-connect-agent updatestartuptty /bye
513 Although all GnuPG components try to start the gpg-agent as needed, this
514 is not possible for the ssh support because ssh does not know about it.
515 Thus if no GnuPG tool which accesses the agent has been run, there is no
516 guarantee that ssh is able to use gpg-agent for authentication. To fix
517 this you may start gpg-agent if needed using this simple command:
520 gpg-connect-agent /bye
523 Adding the @option{--verbose} shows the progress of starting the agent.
527 All the long options may also be given in the configuration file after
528 stripping off the two leading dashes.
532 @node Agent Configuration
533 @section Configuration
535 There are a few configuration files needed for the operation of the
536 agent. By default they may all be found in the current home directory
537 (@pxref{option --homedir}).
542 @cindex gpg-agent.conf
543 This is the standard configuration file read by @command{gpg-agent} on
544 startup. It may contain any valid long option; the leading
545 two dashes may not be entered and the option may not be abbreviated.
546 This file is also read after a @code{SIGHUP} however only a few
547 options will actually have an effect. This default name may be
548 changed on the command line (@pxref{option --options}).
549 You should backup this file.
552 This is the list of trusted keys. You should backup this file.
554 Comment lines, indicated by a leading hash mark, as well as empty
555 lines are ignored. To mark a key as trusted you need to enter its
556 fingerprint followed by a space and a capital letter @code{S}. Colons
557 may optionally be used to separate the bytes of a fingerprint; this
558 allows to cut and paste the fingerprint from a key listing output. If
559 the line is prefixed with a @code{!} the key is explicitly marked as
562 Here is an example where two keys are marked as ultimately trusted
563 and one as not trusted:
567 # CN=Wurzel ZS 3,O=Intevation GmbH,C=DE
568 A6935DD34EF3087973C706FC311AA2CCF733765B S
570 # CN=PCA-1-Verwaltung-02/O=PKI-1-Verwaltung/C=DE
571 DC:BD:69:25:48:BD:BB:7E:31:6E:BB:80:D3:00:80:35:D4:F8:A6:CD S
573 # CN=Root-CA/O=Schlapphuete/L=Pullach/C=DE
574 !14:56:98:D3:FE:9C:CA:5A:31:6E:BC:81:D3:11:4E:00:90:A3:44:C2 S
578 Before entering a key into this file, you need to ensure its
579 authenticity. How to do this depends on your organisation; your
580 administrator might have already entered those keys which are deemed
581 trustworthy enough into this file. Places where to look for the
582 fingerprint of a root certificate are letters received from the CA or
583 the website of the CA (after making 100% sure that this is indeed the
584 website of that CA). You may want to consider disallowing interactive
585 updates of this file by using the @xref{option --no-allow-mark-trusted}.
586 It might even be advisable to change the permissions to read-only so
587 that this file can't be changed inadvertently.
589 As a special feature a line @code{include-default} will include a global
590 list of trusted certificates (e.g. @file{@value{SYSCONFDIR}/trustlist.txt}).
591 This global list is also used if the local list is not available.
593 It is possible to add further flags after the @code{S} for use by the
600 Relax checking of some root certificate requirements. As of now this
601 flag allows the use of root certificates with a missing basicConstraints
602 attribute (despite that it is a MUST for CA certificates) and disables
603 CRL checking for the root certificate.
606 If validation of a certificate finally issued by a CA with this flag set
607 fails, try again using the chain validation model.
614 This file is used when support for the secure shell agent protocol has
615 been enabled (@pxref{option --enable-ssh-support}). Only keys present in
616 this file are used in the SSH protocol. You should backup this file.
618 The @command{ssh-add} tool may be used to add new entries to this file;
619 you may also add them manually. Comment lines, indicated by a leading
620 hash mark, as well as empty lines are ignored. An entry starts with
621 optional whitespace, followed by the keygrip of the key given as 40 hex
622 digits, optionally followed by the caching TTL in seconds and another
623 optional field for arbitrary flags. A non-zero TTL overrides the global
624 default as set by @option{--default-cache-ttl-ssh}.
626 The only flag support is @code{confirm}. If this flag is found for a
627 key, each use of the key will pop up a pinentry to confirm the use of
628 that key. The flag is automatically set if a new key was loaded into
629 @code{gpg-agent} using the option @option{-c} of the @code{ssh-add}
632 The keygrip may be prefixed with a @code{!} to disable an entry entry.
634 The following example lists exactly one key. Note that keys available
635 through a OpenPGP smartcard in the active smartcard reader are
636 implicitly added to this list; i.e. there is no need to list them.
640 # Key added on: 2011-07-20 20:38:46
641 # Fingerprint: 5e:8d:c4:ad:e7:af:6e:27:8a:d6:13:e4:79:ad:0b:81
642 34B62F25E277CF13D3C6BCEBFD3F85D08F0A864B 0 confirm
646 @item private-keys-v1.d/
648 This is the directory where gpg-agent stores the private keys. Each
649 key is stored in a file with the name made up of the keygrip and the
650 suffix @file{key}. You should backup all files in this directory
651 and take great care to keep this backup closed away.
656 Note that on larger installations, it is useful to put predefined
657 files into the directory @file{@value{SYSCONFSKELDIR}} so that newly created
658 users start up with a working configuration. For existing users the
659 a small helper script is provided to create these files (@pxref{addgnupghome}).
668 @section Use of some signals.
669 A running @command{gpg-agent} may be controlled by signals, i.e. using
670 the @command{kill} command to send a signal to the process.
672 Here is a list of supported signals:
678 This signal flushes all cached passphrases and if the program has been
679 started with a configuration file, the configuration file is read
680 again. Only certain options are honored: @code{quiet},
681 @code{verbose}, @code{debug}, @code{debug-all}, @code{debug-level},
682 @code{debug-pinentry},
683 @code{no-grab}, @code{pinentry-program}, @code{default-cache-ttl},
684 @code{max-cache-ttl}, @code{ignore-cache-for-signing},
685 @code{no-allow-external-cache}, @code{allow-emacs-pinentry},
686 @code{no-allow-mark-trusted}, @code{disable-scdaemon}, and
687 @code{disable-check-own-socket}. @code{scdaemon-program} is also
688 supported but due to the current implementation, which calls the
689 scdaemon only once, it is not of much use unless you manually kill the
695 Shuts down the process but waits until all current requests are
696 fulfilled. If the process has received 3 of these signals and requests
697 are still pending, a shutdown is forced.
701 Shuts down the process immediately.
705 Dump internal information to the log file.
709 This signal is used for internal purposes.
720 It is important to set the GPG_TTY environment variable in
721 your login shell, for example in the @file{~/.bashrc} init script:
725 export GPG_TTY=$(tty)
729 If you enabled the Ssh Agent Support, you also need to tell ssh about
730 it by adding this to your init script:
735 if [ "$@{gnupg_SSH_AUTH_SOCK_by:-0@}" -ne $$ ]; then
736 export SSH_AUTH_SOCK="$@{HOME@}/.gnupg/S.gpg-agent.ssh"
747 @section Agent's Assuan Protocol
749 Note: this section does only document the protocol, which is used by
750 GnuPG components; it does not deal with the ssh-agent protocol.
752 The @command{gpg-agent} daemon is started on demand by the GnuPG
755 To identify a key we use a thing called keygrip which is the SHA-1 hash
756 of an canonical encoded S-Expression of the public key as used in
757 Libgcrypt. For the purpose of this interface the keygrip is given as a
758 hex string. The advantage of using this and not the hash of a
759 certificate is that it will be possible to use the same keypair for
760 different protocols, thereby saving space on the token used to keep the
763 The @command{gpg-agent} may send status messages during a command or when
764 returning from a command to inform a client about the progress or result of an
765 operation. For example, the @var{INQUIRE_MAXLEN} status message may be sent
766 during a server inquire to inform the client of the maximum usable length of
767 the inquired data (which should not be exceeded).
770 * Agent PKDECRYPT:: Decrypting a session key
771 * Agent PKSIGN:: Signing a Hash
772 * Agent GENKEY:: Generating a Key
773 * Agent IMPORT:: Importing a Secret Key
774 * Agent EXPORT:: Exporting a Secret Key
775 * Agent ISTRUSTED:: Importing a Root Certificate
776 * Agent GET_PASSPHRASE:: Ask for a passphrase
777 * Agent CLEAR_PASSPHRASE:: Expire a cached passphrase
778 * Agent PRESET_PASSPHRASE:: Set a passphrase for a keygrip
779 * Agent GET_CONFIRMATION:: Ask for confirmation
780 * Agent HAVEKEY:: Check whether a key is available
781 * Agent LEARN:: Register a smartcard
782 * Agent PASSWD:: Change a Passphrase
783 * Agent UPDATESTARTUPTTY:: Change the Standard Display
784 * Agent GETEVENTCOUNTER:: Get the Event Counters
785 * Agent GETINFO:: Return information about the process
786 * Agent OPTION:: Set options for the session
789 @node Agent PKDECRYPT
790 @subsection Decrypting a session key
792 The client asks the server to decrypt a session key. The encrypted
793 session key should have all information needed to select the
794 appropriate secret key or to delegate it to a smartcard.
800 Tell the server about the key to be used for decryption. If this is
801 not used, @command{gpg-agent} may try to figure out the key by trying to
802 decrypt the message with each key available.
808 The agent checks whether this command is allowed and then does an
809 INQUIRY to get the ciphertext the client should then send the cipher
813 S: INQUIRE CIPHERTEXT
819 Please note that the server may send status info lines while reading the
820 data lines from the client. The data send is a SPKI like S-Exp with
826 (<param_name1> <mpi>)
828 (<param_namen> <mpi>)))
831 Where algo is a string with the name of the algorithm; see the libgcrypt
832 documentation for a list of valid algorithms. The number and names of
833 the parameters depend on the algorithm. The agent does return an error
834 if there is an inconsistency.
836 If the decryption was successful the decrypted data is returned by
839 Here is an example session:
843 S: INQUIRE CIPHERTEXT
844 C: D (enc-val elg (a 349324324)
845 C: D (b 3F444677CA)))
847 S: # session key follows
849 S: D (value 1234567890ABCDEF0)
850 S: OK descryption successful
854 The “PADDING” status line is only send if gpg-agent can tell what kind
855 of padding is used. As of now only the value 0 is used to indicate
856 that the padding has been removed.
860 @subsection Signing a Hash
862 The client ask the agent to sign a given hash value. A default key
863 will be chosen if no key has been set. To set a key a client first
870 This can be used multiple times to create multiple signature, the list
871 of keys is reset with the next PKSIGN command or a RESET. The server
872 test whether the key is a valid key to sign something and responds with
876 SETHASH --hash=<name>|<algo> <hexstring>
879 The client can use this command to tell the server about the data <hexstring>
880 (which usually is a hash) to be signed. <algo> is the decimal encoded hash
881 algorithm number as used by Libgcrypt. Either <algo> or --hash=<name>
882 must be given. Valid names for <name> are:
886 The SHA-1 hash algorithm
888 The SHA-256 hash algorithm
890 The RIPE-MD160 hash algorithm
892 The old and broken MD5 hash algorithm
894 A combined hash algorithm as used by the TLS protocol.
898 The actual signing is done using
904 Options are not yet defined, but my later be used to choose among
905 different algorithms. The agent does then some checks, asks for the
906 passphrase and as a result the server returns the signature as an SPKI
907 like S-expression in "D" lines:
912 (<param_name1> <mpi>)
914 (<param_namen> <mpi>)))
918 The operation is affected by the option
921 OPTION use-cache-for-signing=0|1
924 The default of @code{1} uses the cache. Setting this option to @code{0}
925 will lead @command{gpg-agent} to ignore the passphrase cache. Note, that there is
926 also a global command line option for @command{gpg-agent} to globally disable the
930 Here is an example session:
938 S: # I did ask the user whether he really wants to sign
939 S: # I did ask the user for the passphrase
941 C: D ABCDEF012345678901234
943 S: # signature follows
944 S: D (sig-val rsa (s 45435453654612121212))
950 @subsection Generating a Key
952 This is used to create a new keypair and store the secret key inside the
953 active PSE --- which is in most cases a Soft-PSE. An not yet defined
954 option allows to choose the storage location. To get the secret key out
955 of the PSE, a special export tool has to be used.
958 GENKEY [--no-protection] [--preset] [<cache_nonce>]
961 Invokes the key generation process and the server will then inquire
962 on the generation parameters, like:
966 C: D (genkey (rsa (nbits 1024)))
970 The format of the key parameters which depends on the algorithm is of
976 (parameter_name_1 ....)
978 (parameter_name_n ....)))
981 If everything succeeds, the server returns the *public key* in a SPKI
982 like S-Expression like this:
991 Here is an example session:
996 C: D (genkey (rsa (nbits 1024)))
999 S: D (rsa (n 326487324683264) (e 10001)))
1004 The @option{--no-protection} option may be used to prevent prompting for a
1005 passphrase to protect the secret key while leaving the secret key unprotected.
1006 The @option{--preset} option may be used to add the passphrase to the cache
1007 using the default cache parameters.
1009 The @option{--inq-passwd} option may be used to create the key with a
1010 supplied passphrase. When used the agent does an inquiry with the
1011 keyword @code{NEWPASSWD} to retrieve that passphrase. This option
1012 takes precedence over @option{--no-protection}; however if the client
1013 sends a empty (zero-length) passphrase, this is identical to
1014 @option{--no-protection}.
1017 @subsection Importing a Secret Key
1019 This operation is not yet supported by GpgAgent. Specialized tools
1020 are to be used for this.
1022 There is no actual need because we can expect that secret keys
1023 created by a 3rd party are stored on a smartcard. If we have
1024 generated the key ourself, we do not need to import it.
1027 @subsection Export a Secret Key
1031 Should be done by an extra tool.
1033 @node Agent ISTRUSTED
1034 @subsection Importing a Root Certificate
1036 Actually we do not import a Root Cert but provide a way to validate
1037 any piece of data by storing its Hash along with a description and
1038 an identifier in the PSE. Here is the interface description:
1041 ISTRUSTED <fingerprint>
1044 Check whether the OpenPGP primary key or the X.509 certificate with the
1045 given fingerprint is an ultimately trusted key or a trusted Root CA
1046 certificate. The fingerprint should be given as a hexstring (without
1047 any blanks or colons or whatever in between) and may be left padded with
1048 00 in case of an MD5 fingerprint. GPGAgent will answer with:
1054 The key is in the table of trusted keys.
1057 ERR 304 (Not Trusted)
1060 The key is not in this table.
1062 Gpg needs the entire list of trusted keys to maintain the web of
1063 trust; the following command is therefore quite helpful:
1069 GpgAgent returns a list of trusted keys line by line:
1072 S: D 000000001234454556565656677878AF2F1ECCFF P
1073 S: D 340387563485634856435645634856438576457A P
1074 S: D FEDC6532453745367FD83474357495743757435D S
1078 The first item on a line is the hexified fingerprint where MD5
1079 fingerprints are @code{00} padded to the left and the second item is a
1080 flag to indicate the type of key (so that gpg is able to only take care
1081 of PGP keys). P = OpenPGP, S = S/MIME. A client should ignore the rest
1082 of the line, so that we can extend the format in the future.
1084 Finally a client should be able to mark a key as trusted:
1087 MARKTRUSTED @var{fingerprint} "P"|"S"
1090 The server will then pop up a window to ask the user whether she
1091 really trusts this key. For this it will probably ask for a text to
1092 be displayed like this:
1095 S: INQUIRE TRUSTDESC
1096 C: D Do you trust the key with the fingerprint @@FPR@@
1097 C: D bla fasel blurb.
1102 Known sequences with the pattern @@foo@@ are replaced according to this
1107 Format the fingerprint according to gpg rules for a v3 keys.
1109 Format the fingerprint according to gpg rules for a v4 keys.
1111 Choose an appropriate format to format the fingerprint.
1113 Replaced by a single @code{@@}
1116 @node Agent GET_PASSPHRASE
1117 @subsection Ask for a passphrase
1119 This function is usually used to ask for a passphrase to be used for
1120 symmetric encryption, but may also be used by programs which need
1121 special handling of passphrases. This command uses a syntax which helps
1122 clients to use the agent with minimum effort.
1125 GET_PASSPHRASE [--data] [--check] [--no-ask] [--repeat[=N]] \
1126 [--qualitybar] @var{cache_id} \
1127 [@var{error_message} @var{prompt} @var{description}]
1130 @var{cache_id} is expected to be a string used to identify a cached
1131 passphrase. Use a @code{X} to bypass the cache. With no other
1132 arguments the agent returns a cached passphrase or an error. By
1133 convention either the hexified fingerprint of the key shall be used for
1134 @var{cache_id} or an arbitrary string prefixed with the name of the
1135 calling application and a colon: Like @code{gpg:somestring}.
1137 @var{error_message} is either a single @code{X} for no error message or
1138 a string to be shown as an error message like (e.g. "invalid
1139 passphrase"). Blanks must be percent escaped or replaced by @code{+}'.
1141 @var{prompt} is either a single @code{X} for a default prompt or the
1142 text to be shown as the prompt. Blanks must be percent escaped or
1143 replaced by @code{+}.
1145 @var{description} is a text shown above the entry field. Blanks must be
1146 percent escaped or replaced by @code{+}.
1148 The agent either returns with an error or with a OK followed by the hex
1149 encoded passphrase. Note that the length of the strings is implicitly
1150 limited by the maximum length of a command. If the option
1151 @option{--data} is used, the passphrase is not returned on the OK line
1152 but by regular data lines; this is the preferred method.
1154 If the option @option{--check} is used, the standard passphrase
1155 constraints checks are applied. A check is not done if the passphrase
1156 has been found in the cache.
1158 If the option @option{--no-ask} is used and the passphrase is not in the
1159 cache the user will not be asked to enter a passphrase but the error
1160 code @code{GPG_ERR_NO_DATA} is returned.
1162 If the option @option{--qualitybar} is used and a minimum passphrase
1163 length has been configured, a visual indication of the entered
1164 passphrase quality is shown.
1167 CLEAR_PASSPHRASE @var{cache_id}
1170 may be used to invalidate the cache entry for a passphrase. The
1171 function returns with OK even when there is no cached passphrase.
1175 @node Agent CLEAR_PASSPHRASE
1176 @subsection Remove a cached passphrase
1178 Use this command to remove a cached passphrase.
1181 CLEAR_PASSPHRASE [--mode=normal] <cache_id>
1184 The @option{--mode=normal} option can be used to clear a @var{cache_id} that
1185 was set by gpg-agent.
1188 @node Agent PRESET_PASSPHRASE
1189 @subsection Set a passphrase for a keygrip
1191 This command adds a passphrase to the cache for the specified @var{keygrip}.
1194 PRESET_PASSPHRASE [--inquire] <string_or_keygrip> <timeout> [<hexstring>]
1197 The passphrase is a hexidecimal string when specified. When not specified, the
1198 passphrase will be retrieved from the pinentry module unless the
1199 @option{--inquire} option was specified in which case the passphrase will be
1200 retrieved from the client.
1202 The @var{timeout} parameter keeps the passphrase cached for the specified
1203 number of seconds. A value of @code{-1} means infinate while @code{0} means
1204 the default (currently only a timeout of -1 is allowed, which means to never
1208 @node Agent GET_CONFIRMATION
1209 @subsection Ask for confirmation
1211 This command may be used to ask for a simple confirmation by
1212 presenting a text and 2 buttons: Okay and Cancel.
1215 GET_CONFIRMATION @var{description}
1218 @var{description}is displayed along with a Okay and Cancel
1219 button. Blanks must be percent escaped or replaced by @code{+}. A
1220 @code{X} may be used to display confirmation dialog with a default
1223 The agent either returns with an error or with a OK. Note, that the
1224 length of @var{description} is implicitly limited by the maximum
1225 length of a command.
1230 @subsection Check whether a key is available
1232 This can be used to see whether a secret key is available. It does
1233 not return any information on whether the key is somehow protected.
1236 HAVEKEY @var{keygrips}
1239 The agent answers either with OK or @code{No_Secret_Key} (208). The
1240 caller may want to check for other error codes as well. More than one
1241 keygrip may be given. In this case the command returns success if at
1242 least one of the keygrips corresponds to an available secret key.
1246 @subsection Register a smartcard
1252 This command is used to register a smartcard. With the --send
1253 option given the certificates are send back.
1257 @subsection Change a Passphrase
1260 PASSWD [--cache-nonce=<c>] [--passwd-nonce=<s>] [--preset] @var{keygrip}
1263 This command is used to interactively change the passphrase of the key
1264 identified by the hex string @var{keygrip}. The @option{--preset}
1265 option may be used to add the new passphrase to the cache using the
1266 default cache parameters.
1269 @node Agent UPDATESTARTUPTTY
1270 @subsection Change the standard display
1276 Set the startup TTY and X-DISPLAY variables to the values of this
1277 session. This command is useful to direct future pinentry invocations
1278 to another screen. It is only required because there is no way in the
1279 ssh-agent protocol to convey this information.
1282 @node Agent GETEVENTCOUNTER
1283 @subsection Get the Event Counters
1289 This function return one status line with the current values of the
1290 event counters. The event counters are useful to avoid polling by
1291 delaying a poll until something has changed. The values are decimal
1292 numbers in the range @code{0} to @code{UINT_MAX} and wrapping around to
1293 0. The actual values should not be relied upon; they shall only be used
1296 The currently defined counters are are:
1299 Incremented with any change of any of the other counters.
1301 Incremented for added or removed private keys.
1303 Incremented for changes of the card readers stati.
1307 @subsection Return information about the process
1309 This is a multipurpose function to return a variety of information.
1315 The value of @var{what} specifies the kind of information returned:
1318 Return the version of the program.
1320 Return the process id of the process.
1322 Return the name of the socket used to connect the agent.
1323 @item ssh_socket_name
1324 Return the name of the socket used for SSH connections. If SSH support
1325 has not been enabled the error @code{GPG_ERR_NO_DATA} will be returned.
1329 @subsection Set options for the session
1331 Here is a list of session options which are not yet described with
1332 other commands. The general syntax for an Assuan option is:
1335 OPTION @var{key}=@var{value}
1339 Supported @var{key}s are:
1342 @item agent-awareness
1343 This may be used to tell gpg-agent of which gpg-agent version the
1344 client is aware of. gpg-agent uses this information to enable
1345 features which might break older clients.
1348 Change the session's environment to be used for the
1349 Pinentry. Valid values are:
1353 Delete envvar @var{name}
1355 Set envvar @var{name} to the empty string
1356 @item @var{name}=@var{value}
1357 Set envvar @var{name} to the string @var{value}.
1360 @item use-cache-for-signing
1361 See Assuan command @code{PKSIGN}.
1363 @item allow-pinentry-notify
1364 This does not need any value. It is used to enable the
1365 PINENTRY_LAUNCHED inquiry.
1368 This option is used to change the operation mode of the pinentry. The
1369 following values are defined:
1373 This is the default mode which pops up a pinentry as needed.
1376 Instead of popping up a pinentry, return the error code
1377 @code{GPG_ERR_CANCELED}.
1380 Instead of popping up a pinentry, return the error code
1381 @code{GPG_ERR_NO_PIN_ENTRY}.
1384 Use a loopback pinentry. This fakes a pinentry by using inquiries
1385 back to the caller to ask for a passphrase. This option may only be
1386 set if the agent has been configured for that.
1387 Use the @xref{option --allow-loopback-pinentry}.
1391 @item cache-ttl-opt-preset
1392 This option sets the cache TTL for new entries created by GENKEY and
1393 PASSWD commands when using the @option{--preset} option. It it is not
1394 used a default value is used.
1397 Instead of using the standard S2K count (which is computed on the
1398 fly), the given S2K count is used for new keys or when changing the
1399 passphrase of a key. Values below 65536 are considered to be 0. This
1400 option is valid for the entire session or until reset to 0. This
1401 option is useful if the key is later used on boxes which are either
1402 much slower or faster than the actual box.
1411 @command{gpg-connect-agent}(1),
1412 @command{scdaemon}(1)
1414 @include see-also-note.texi