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
332 is 600 seconds. Each time a cache entry is accessed, the entry's
333 timer is reset. To set an entry's maximum lifetime, use
334 @command{max-cache-ttl}.
336 @item --default-cache-ttl-ssh @var{n}
337 @opindex default-cache-ttl
338 Set the time a cache entry used for SSH keys is valid to @var{n}
339 seconds. The default is 1800 seconds. Each time a cache entry is
340 accessed, the entry's timer is reset. To set an entry's maximum
341 lifetime, use @command{max-cache-ttl-ssh}.
343 @item --max-cache-ttl @var{n}
344 @opindex max-cache-ttl
345 Set the maximum time a cache entry is valid to @var{n} seconds. After
346 this time a cache entry will be expired even if it has been accessed
347 recently or has been set using @command{gpg-preset-passphrase}. The
348 default is 2 hours (7200 seconds).
350 @item --max-cache-ttl-ssh @var{n}
351 @opindex max-cache-ttl-ssh
352 Set the maximum time a cache entry used for SSH keys is valid to
353 @var{n} seconds. After this time a cache entry will be expired even
354 if it has been accessed recently or has been set using
355 @command{gpg-preset-passphrase}. The default is 2 hours (7200
358 @item --enforce-passphrase-constraints
359 @opindex enforce-passphrase-constraints
360 Enforce the passphrase constraints by not allowing the user to bypass
361 them using the ``Take it anyway'' button.
363 @item --min-passphrase-len @var{n}
364 @opindex min-passphrase-len
365 Set the minimal length of a passphrase. When entering a new passphrase
366 shorter than this value a warning will be displayed. Defaults to 8.
368 @item --min-passphrase-nonalpha @var{n}
369 @opindex min-passphrase-nonalpha
370 Set the minimal number of digits or special characters required in a
371 passphrase. When entering a new passphrase with less than this number
372 of digits or special characters a warning will be displayed. Defaults
375 @item --check-passphrase-pattern @var{file}
376 @opindex check-passphrase-pattern
377 Check the passphrase against the pattern given in @var{file}. When
378 entering a new passphrase matching one of these pattern a warning will
379 be displayed. @var{file} should be an absolute filename. The default is
380 not to use any pattern file.
382 Security note: It is known that checking a passphrase against a list of
383 pattern or even against a complete dictionary is not very effective to
384 enforce good passphrases. Users will soon figure up ways to bypass such
385 a policy. A better policy is to educate users on good security
386 behavior and optionally to run a passphrase cracker regularly on all
387 users passphrases to catch the very simple ones.
389 @item --max-passphrase-days @var{n}
390 @opindex max-passphrase-days
391 Ask the user to change the passphrase if @var{n} days have passed since
392 the last change. With @option{--enforce-passphrase-constraints} set the
393 user may not bypass this check.
395 @item --enable-passphrase-history
396 @opindex enable-passphrase-history
397 This option does nothing yet.
399 @item --pinentry-program @var{filename}
400 @opindex pinentry-program
401 Use program @var{filename} as the PIN entry. The default is
402 installation dependent. With the default configuration the name of
403 the default pinentry is @file{pinentry}; if that file does not exist
404 but a @file{pinentry-basic} exist the latter is used.
406 @item --pinentry-touch-file @var{filename}
407 @opindex pinentry-touch-file
408 By default the filename of the socket gpg-agent is listening for
409 requests is passed to Pinentry, so that it can touch that file before
410 exiting (it does this only in curses mode). This option changes the
411 file passed to Pinentry to @var{filename}. The special name
412 @code{/dev/null} may be used to completely disable this feature. Note
413 that Pinentry will not create that file, it will only change the
414 modification and access time.
417 @item --scdaemon-program @var{filename}
418 @opindex scdaemon-program
419 Use program @var{filename} as the Smartcard daemon. The default is
420 installation dependent and can be shown with the @command{gpgconf}
423 @item --disable-scdaemon
424 @opindex disable-scdaemon
425 Do not make use of the scdaemon tool. This option has the effect of
426 disabling the ability to do smartcard operations. Note, that enabling
427 this option at runtime does not kill an already forked scdaemon.
429 @item --disable-check-own-socket
430 @opindex disable-check-own-socket
431 @command{gpg-agent} employs a periodic self-test to detect a stolen
432 socket. This usually means a second instance of @command{gpg-agent}
433 has taken over the socket and @command{gpg-agent} will then terminate
434 itself. This option may be used to disable this self-test for
437 @item --use-standard-socket
438 @itemx --no-use-standard-socket
439 @itemx --use-standard-socket-p
440 @opindex use-standard-socket
441 @opindex no-use-standard-socket
442 @opindex use-standard-socket-p
443 Since GnuPG 2.1 the standard socket is always used. These options
444 have no more effect. The command @code{gpg-agent
445 --use-standard-socket-p} will thus always return success.
447 @item --display @var{string}
448 @itemx --ttyname @var{string}
449 @itemx --ttytype @var{string}
450 @itemx --lc-ctype @var{string}
451 @itemx --lc-messages @var{string}
452 @itemx --xauthority @var{string}
459 These options are used with the server mode to pass localization
463 @itemx --keep-display
465 @opindex keep-display
466 Ignore requests to change the current @code{tty} or X window system's
467 @code{DISPLAY} variable respectively. This is useful to lock the
468 pinentry to pop up at the @code{tty} or display you started the agent.
471 @anchor{option --extra-socket}
472 @item --extra-socket @var{name}
473 @opindex extra-socket
474 Also listen on native gpg-agent connections on the given socket. The
475 intended use for this extra socket is to setup a Unix domain socket
476 forwarding from a remote machine to this socket on the local machine.
477 A @command{gpg} running on the remote machine may then connect to the
478 local gpg-agent and use its private keys. This allows to decrypt or
479 sign data on a remote machine without exposing the private keys to the
483 @anchor{option --enable-ssh-support}
484 @item --enable-ssh-support
485 @itemx --enable-putty-support
486 @opindex enable-ssh-support
487 @opindex enable-putty-support
489 Enable the OpenSSH Agent protocol.
491 In this mode of operation, the agent does not only implement the
492 gpg-agent protocol, but also the agent protocol used by OpenSSH
493 (through a separate socket). Consequently, it should be possible to use
494 the gpg-agent as a drop-in replacement for the well known ssh-agent.
496 SSH Keys, which are to be used through the agent, need to be added to
497 the gpg-agent initially through the ssh-add utility. When a key is
498 added, ssh-add will ask for the password of the provided key file and
499 send the unprotected key material to the agent; this causes the
500 gpg-agent to ask for a passphrase, which is to be used for encrypting
501 the newly received key and storing it in a gpg-agent specific
504 Once a key has been added to the gpg-agent this way, the gpg-agent
505 will be ready to use the key.
507 Note: in case the gpg-agent receives a signature request, the user might
508 need to be prompted for a passphrase, which is necessary for decrypting
509 the stored key. Since the ssh-agent protocol does not contain a
510 mechanism for telling the agent on which display/terminal it is running,
511 gpg-agent's ssh-support will use the TTY or X display where gpg-agent
512 has been started. To switch this display to the current one, the
513 following command may be used:
516 gpg-connect-agent updatestartuptty /bye
519 Although all GnuPG components try to start the gpg-agent as needed, this
520 is not possible for the ssh support because ssh does not know about it.
521 Thus if no GnuPG tool which accesses the agent has been run, there is no
522 guarantee that ssh is able to use gpg-agent for authentication. To fix
523 this you may start gpg-agent if needed using this simple command:
526 gpg-connect-agent /bye
529 Adding the @option{--verbose} shows the progress of starting the agent.
531 The @option{--enable-putty-support} is only available under Windows
532 and allows the use of gpg-agent with the ssh implementation
533 @command{putty}. This is similar to the regular ssh-agent support but
534 makes use of Windows message queue as required by @command{putty}.
539 All the long options may also be given in the configuration file after
540 stripping off the two leading dashes.
544 @node Agent Configuration
545 @section Configuration
547 There are a few configuration files needed for the operation of the
548 agent. By default they may all be found in the current home directory
549 (@pxref{option --homedir}).
554 @cindex gpg-agent.conf
555 This is the standard configuration file read by @command{gpg-agent} on
556 startup. It may contain any valid long option; the leading
557 two dashes may not be entered and the option may not be abbreviated.
558 This file is also read after a @code{SIGHUP} however only a few
559 options will actually have an effect. This default name may be
560 changed on the command line (@pxref{option --options}).
561 You should backup this file.
564 This is the list of trusted keys. You should backup this file.
566 Comment lines, indicated by a leading hash mark, as well as empty
567 lines are ignored. To mark a key as trusted you need to enter its
568 fingerprint followed by a space and a capital letter @code{S}. Colons
569 may optionally be used to separate the bytes of a fingerprint; this
570 allows to cut and paste the fingerprint from a key listing output. If
571 the line is prefixed with a @code{!} the key is explicitly marked as
574 Here is an example where two keys are marked as ultimately trusted
575 and one as not trusted:
579 # CN=Wurzel ZS 3,O=Intevation GmbH,C=DE
580 A6935DD34EF3087973C706FC311AA2CCF733765B S
582 # CN=PCA-1-Verwaltung-02/O=PKI-1-Verwaltung/C=DE
583 DC:BD:69:25:48:BD:BB:7E:31:6E:BB:80:D3:00:80:35:D4:F8:A6:CD S
585 # CN=Root-CA/O=Schlapphuete/L=Pullach/C=DE
586 !14:56:98:D3:FE:9C:CA:5A:31:6E:BC:81:D3:11:4E:00:90:A3:44:C2 S
590 Before entering a key into this file, you need to ensure its
591 authenticity. How to do this depends on your organisation; your
592 administrator might have already entered those keys which are deemed
593 trustworthy enough into this file. Places where to look for the
594 fingerprint of a root certificate are letters received from the CA or
595 the website of the CA (after making 100% sure that this is indeed the
596 website of that CA). You may want to consider disallowing interactive
597 updates of this file by using the @xref{option --no-allow-mark-trusted}.
598 It might even be advisable to change the permissions to read-only so
599 that this file can't be changed inadvertently.
601 As a special feature a line @code{include-default} will include a global
602 list of trusted certificates (e.g. @file{@value{SYSCONFDIR}/trustlist.txt}).
603 This global list is also used if the local list is not available.
605 It is possible to add further flags after the @code{S} for use by the
612 Relax checking of some root certificate requirements. As of now this
613 flag allows the use of root certificates with a missing basicConstraints
614 attribute (despite that it is a MUST for CA certificates) and disables
615 CRL checking for the root certificate.
618 If validation of a certificate finally issued by a CA with this flag set
619 fails, try again using the chain validation model.
626 This file is used when support for the secure shell agent protocol has
627 been enabled (@pxref{option --enable-ssh-support}). Only keys present in
628 this file are used in the SSH protocol. You should backup this file.
630 The @command{ssh-add} tool may be used to add new entries to this file;
631 you may also add them manually. Comment lines, indicated by a leading
632 hash mark, as well as empty lines are ignored. An entry starts with
633 optional whitespace, followed by the keygrip of the key given as 40 hex
634 digits, optionally followed by the caching TTL in seconds and another
635 optional field for arbitrary flags. A non-zero TTL overrides the global
636 default as set by @option{--default-cache-ttl-ssh}.
638 The only flag support is @code{confirm}. If this flag is found for a
639 key, each use of the key will pop up a pinentry to confirm the use of
640 that key. The flag is automatically set if a new key was loaded into
641 @code{gpg-agent} using the option @option{-c} of the @code{ssh-add}
644 The keygrip may be prefixed with a @code{!} to disable an entry entry.
646 The following example lists exactly one key. Note that keys available
647 through a OpenPGP smartcard in the active smartcard reader are
648 implicitly added to this list; i.e. there is no need to list them.
652 # Key added on: 2011-07-20 20:38:46
653 # Fingerprint: 5e:8d:c4:ad:e7:af:6e:27:8a:d6:13:e4:79:ad:0b:81
654 34B62F25E277CF13D3C6BCEBFD3F85D08F0A864B 0 confirm
658 @item private-keys-v1.d/
660 This is the directory where gpg-agent stores the private keys. Each
661 key is stored in a file with the name made up of the keygrip and the
662 suffix @file{key}. You should backup all files in this directory
663 and take great care to keep this backup closed away.
668 Note that on larger installations, it is useful to put predefined
669 files into the directory @file{@value{SYSCONFSKELDIR}} so that newly created
670 users start up with a working configuration. For existing users the
671 a small helper script is provided to create these files (@pxref{addgnupghome}).
680 @section Use of some signals.
681 A running @command{gpg-agent} may be controlled by signals, i.e. using
682 the @command{kill} command to send a signal to the process.
684 Here is a list of supported signals:
690 This signal flushes all cached passphrases and if the program has been
691 started with a configuration file, the configuration file is read
692 again. Only certain options are honored: @code{quiet},
693 @code{verbose}, @code{debug}, @code{debug-all}, @code{debug-level},
694 @code{debug-pinentry},
695 @code{no-grab}, @code{pinentry-program}, @code{default-cache-ttl},
696 @code{max-cache-ttl}, @code{ignore-cache-for-signing},
697 @code{no-allow-external-cache}, @code{allow-emacs-pinentry},
698 @code{no-allow-mark-trusted}, @code{disable-scdaemon}, and
699 @code{disable-check-own-socket}. @code{scdaemon-program} is also
700 supported but due to the current implementation, which calls the
701 scdaemon only once, it is not of much use unless you manually kill the
707 Shuts down the process but waits until all current requests are
708 fulfilled. If the process has received 3 of these signals and requests
709 are still pending, a shutdown is forced.
713 Shuts down the process immediately.
717 Dump internal information to the log file.
721 This signal is used for internal purposes.
732 It is important to set the GPG_TTY environment variable in
733 your login shell, for example in the @file{~/.bashrc} init script:
737 export GPG_TTY=$(tty)
741 If you enabled the Ssh Agent Support, you also need to tell ssh about
742 it by adding this to your init script:
747 if [ "$@{gnupg_SSH_AUTH_SOCK_by:-0@}" -ne $$ ]; then
748 export SSH_AUTH_SOCK="$@{HOME@}/.gnupg/S.gpg-agent.ssh"
759 @section Agent's Assuan Protocol
761 Note: this section does only document the protocol, which is used by
762 GnuPG components; it does not deal with the ssh-agent protocol.
764 The @command{gpg-agent} daemon is started on demand by the GnuPG
767 To identify a key we use a thing called keygrip which is the SHA-1 hash
768 of an canonical encoded S-Expression of the public key as used in
769 Libgcrypt. For the purpose of this interface the keygrip is given as a
770 hex string. The advantage of using this and not the hash of a
771 certificate is that it will be possible to use the same keypair for
772 different protocols, thereby saving space on the token used to keep the
775 The @command{gpg-agent} may send status messages during a command or when
776 returning from a command to inform a client about the progress or result of an
777 operation. For example, the @var{INQUIRE_MAXLEN} status message may be sent
778 during a server inquire to inform the client of the maximum usable length of
779 the inquired data (which should not be exceeded).
782 * Agent PKDECRYPT:: Decrypting a session key
783 * Agent PKSIGN:: Signing a Hash
784 * Agent GENKEY:: Generating a Key
785 * Agent IMPORT:: Importing a Secret Key
786 * Agent EXPORT:: Exporting a Secret Key
787 * Agent ISTRUSTED:: Importing a Root Certificate
788 * Agent GET_PASSPHRASE:: Ask for a passphrase
789 * Agent CLEAR_PASSPHRASE:: Expire a cached passphrase
790 * Agent PRESET_PASSPHRASE:: Set a passphrase for a keygrip
791 * Agent GET_CONFIRMATION:: Ask for confirmation
792 * Agent HAVEKEY:: Check whether a key is available
793 * Agent LEARN:: Register a smartcard
794 * Agent PASSWD:: Change a Passphrase
795 * Agent UPDATESTARTUPTTY:: Change the Standard Display
796 * Agent GETEVENTCOUNTER:: Get the Event Counters
797 * Agent GETINFO:: Return information about the process
798 * Agent OPTION:: Set options for the session
801 @node Agent PKDECRYPT
802 @subsection Decrypting a session key
804 The client asks the server to decrypt a session key. The encrypted
805 session key should have all information needed to select the
806 appropriate secret key or to delegate it to a smartcard.
812 Tell the server about the key to be used for decryption. If this is
813 not used, @command{gpg-agent} may try to figure out the key by trying to
814 decrypt the message with each key available.
820 The agent checks whether this command is allowed and then does an
821 INQUIRY to get the ciphertext the client should then send the cipher
825 S: INQUIRE CIPHERTEXT
831 Please note that the server may send status info lines while reading the
832 data lines from the client. The data send is a SPKI like S-Exp with
838 (<param_name1> <mpi>)
840 (<param_namen> <mpi>)))
843 Where algo is a string with the name of the algorithm; see the libgcrypt
844 documentation for a list of valid algorithms. The number and names of
845 the parameters depend on the algorithm. The agent does return an error
846 if there is an inconsistency.
848 If the decryption was successful the decrypted data is returned by
851 Here is an example session:
855 S: INQUIRE CIPHERTEXT
856 C: D (enc-val elg (a 349324324)
857 C: D (b 3F444677CA)))
859 S: # session key follows
861 S: D (value 1234567890ABCDEF0)
862 S: OK descryption successful
866 The “PADDING” status line is only send if gpg-agent can tell what kind
867 of padding is used. As of now only the value 0 is used to indicate
868 that the padding has been removed.
872 @subsection Signing a Hash
874 The client ask the agent to sign a given hash value. A default key
875 will be chosen if no key has been set. To set a key a client first
882 This can be used multiple times to create multiple signature, the list
883 of keys is reset with the next PKSIGN command or a RESET. The server
884 test whether the key is a valid key to sign something and responds with
888 SETHASH --hash=<name>|<algo> <hexstring>
891 The client can use this command to tell the server about the data <hexstring>
892 (which usually is a hash) to be signed. <algo> is the decimal encoded hash
893 algorithm number as used by Libgcrypt. Either <algo> or --hash=<name>
894 must be given. Valid names for <name> are:
898 The SHA-1 hash algorithm
900 The SHA-256 hash algorithm
902 The RIPE-MD160 hash algorithm
904 The old and broken MD5 hash algorithm
906 A combined hash algorithm as used by the TLS protocol.
910 The actual signing is done using
916 Options are not yet defined, but my later be used to choose among
917 different algorithms. The agent does then some checks, asks for the
918 passphrase and as a result the server returns the signature as an SPKI
919 like S-expression in "D" lines:
924 (<param_name1> <mpi>)
926 (<param_namen> <mpi>)))
930 The operation is affected by the option
933 OPTION use-cache-for-signing=0|1
936 The default of @code{1} uses the cache. Setting this option to @code{0}
937 will lead @command{gpg-agent} to ignore the passphrase cache. Note, that there is
938 also a global command line option for @command{gpg-agent} to globally disable the
942 Here is an example session:
950 S: # I did ask the user whether he really wants to sign
951 S: # I did ask the user for the passphrase
953 C: D ABCDEF012345678901234
955 S: # signature follows
956 S: D (sig-val rsa (s 45435453654612121212))
962 @subsection Generating a Key
964 This is used to create a new keypair and store the secret key inside the
965 active PSE --- which is in most cases a Soft-PSE. An not yet defined
966 option allows to choose the storage location. To get the secret key out
967 of the PSE, a special export tool has to be used.
970 GENKEY [--no-protection] [--preset] [<cache_nonce>]
973 Invokes the key generation process and the server will then inquire
974 on the generation parameters, like:
978 C: D (genkey (rsa (nbits 1024)))
982 The format of the key parameters which depends on the algorithm is of
988 (parameter_name_1 ....)
990 (parameter_name_n ....)))
993 If everything succeeds, the server returns the *public key* in a SPKI
994 like S-Expression like this:
1003 Here is an example session:
1008 C: D (genkey (rsa (nbits 1024)))
1011 S: D (rsa (n 326487324683264) (e 10001)))
1016 The @option{--no-protection} option may be used to prevent prompting for a
1017 passphrase to protect the secret key while leaving the secret key unprotected.
1018 The @option{--preset} option may be used to add the passphrase to the cache
1019 using the default cache parameters.
1021 The @option{--inq-passwd} option may be used to create the key with a
1022 supplied passphrase. When used the agent does an inquiry with the
1023 keyword @code{NEWPASSWD} to retrieve that passphrase. This option
1024 takes precedence over @option{--no-protection}; however if the client
1025 sends a empty (zero-length) passphrase, this is identical to
1026 @option{--no-protection}.
1029 @subsection Importing a Secret Key
1031 This operation is not yet supported by GpgAgent. Specialized tools
1032 are to be used for this.
1034 There is no actual need because we can expect that secret keys
1035 created by a 3rd party are stored on a smartcard. If we have
1036 generated the key ourself, we do not need to import it.
1039 @subsection Export a Secret Key
1043 Should be done by an extra tool.
1045 @node Agent ISTRUSTED
1046 @subsection Importing a Root Certificate
1048 Actually we do not import a Root Cert but provide a way to validate
1049 any piece of data by storing its Hash along with a description and
1050 an identifier in the PSE. Here is the interface description:
1053 ISTRUSTED <fingerprint>
1056 Check whether the OpenPGP primary key or the X.509 certificate with the
1057 given fingerprint is an ultimately trusted key or a trusted Root CA
1058 certificate. The fingerprint should be given as a hexstring (without
1059 any blanks or colons or whatever in between) and may be left padded with
1060 00 in case of an MD5 fingerprint. GPGAgent will answer with:
1066 The key is in the table of trusted keys.
1069 ERR 304 (Not Trusted)
1072 The key is not in this table.
1074 Gpg needs the entire list of trusted keys to maintain the web of
1075 trust; the following command is therefore quite helpful:
1081 GpgAgent returns a list of trusted keys line by line:
1084 S: D 000000001234454556565656677878AF2F1ECCFF P
1085 S: D 340387563485634856435645634856438576457A P
1086 S: D FEDC6532453745367FD83474357495743757435D S
1090 The first item on a line is the hexified fingerprint where MD5
1091 fingerprints are @code{00} padded to the left and the second item is a
1092 flag to indicate the type of key (so that gpg is able to only take care
1093 of PGP keys). P = OpenPGP, S = S/MIME. A client should ignore the rest
1094 of the line, so that we can extend the format in the future.
1096 Finally a client should be able to mark a key as trusted:
1099 MARKTRUSTED @var{fingerprint} "P"|"S"
1102 The server will then pop up a window to ask the user whether she
1103 really trusts this key. For this it will probably ask for a text to
1104 be displayed like this:
1107 S: INQUIRE TRUSTDESC
1108 C: D Do you trust the key with the fingerprint @@FPR@@
1109 C: D bla fasel blurb.
1114 Known sequences with the pattern @@foo@@ are replaced according to this
1119 Format the fingerprint according to gpg rules for a v3 keys.
1121 Format the fingerprint according to gpg rules for a v4 keys.
1123 Choose an appropriate format to format the fingerprint.
1125 Replaced by a single @code{@@}
1128 @node Agent GET_PASSPHRASE
1129 @subsection Ask for a passphrase
1131 This function is usually used to ask for a passphrase to be used for
1132 symmetric encryption, but may also be used by programs which need
1133 special handling of passphrases. This command uses a syntax which helps
1134 clients to use the agent with minimum effort.
1137 GET_PASSPHRASE [--data] [--check] [--no-ask] [--repeat[=N]] \
1138 [--qualitybar] @var{cache_id} \
1139 [@var{error_message} @var{prompt} @var{description}]
1142 @var{cache_id} is expected to be a string used to identify a cached
1143 passphrase. Use a @code{X} to bypass the cache. With no other
1144 arguments the agent returns a cached passphrase or an error. By
1145 convention either the hexified fingerprint of the key shall be used for
1146 @var{cache_id} or an arbitrary string prefixed with the name of the
1147 calling application and a colon: Like @code{gpg:somestring}.
1149 @var{error_message} is either a single @code{X} for no error message or
1150 a string to be shown as an error message like (e.g. "invalid
1151 passphrase"). Blanks must be percent escaped or replaced by @code{+}'.
1153 @var{prompt} is either a single @code{X} for a default prompt or the
1154 text to be shown as the prompt. Blanks must be percent escaped or
1155 replaced by @code{+}.
1157 @var{description} is a text shown above the entry field. Blanks must be
1158 percent escaped or replaced by @code{+}.
1160 The agent either returns with an error or with a OK followed by the hex
1161 encoded passphrase. Note that the length of the strings is implicitly
1162 limited by the maximum length of a command. If the option
1163 @option{--data} is used, the passphrase is not returned on the OK line
1164 but by regular data lines; this is the preferred method.
1166 If the option @option{--check} is used, the standard passphrase
1167 constraints checks are applied. A check is not done if the passphrase
1168 has been found in the cache.
1170 If the option @option{--no-ask} is used and the passphrase is not in the
1171 cache the user will not be asked to enter a passphrase but the error
1172 code @code{GPG_ERR_NO_DATA} is returned.
1174 If the option @option{--qualitybar} is used and a minimum passphrase
1175 length has been configured, a visual indication of the entered
1176 passphrase quality is shown.
1179 CLEAR_PASSPHRASE @var{cache_id}
1182 may be used to invalidate the cache entry for a passphrase. The
1183 function returns with OK even when there is no cached passphrase.
1187 @node Agent CLEAR_PASSPHRASE
1188 @subsection Remove a cached passphrase
1190 Use this command to remove a cached passphrase.
1193 CLEAR_PASSPHRASE [--mode=normal] <cache_id>
1196 The @option{--mode=normal} option can be used to clear a @var{cache_id} that
1197 was set by gpg-agent.
1200 @node Agent PRESET_PASSPHRASE
1201 @subsection Set a passphrase for a keygrip
1203 This command adds a passphrase to the cache for the specified @var{keygrip}.
1206 PRESET_PASSPHRASE [--inquire] <string_or_keygrip> <timeout> [<hexstring>]
1209 The passphrase is a hexidecimal string when specified. When not specified, the
1210 passphrase will be retrieved from the pinentry module unless the
1211 @option{--inquire} option was specified in which case the passphrase will be
1212 retrieved from the client.
1214 The @var{timeout} parameter keeps the passphrase cached for the specified
1215 number of seconds. A value of @code{-1} means infinate while @code{0} means
1216 the default (currently only a timeout of -1 is allowed, which means to never
1220 @node Agent GET_CONFIRMATION
1221 @subsection Ask for confirmation
1223 This command may be used to ask for a simple confirmation by
1224 presenting a text and 2 buttons: Okay and Cancel.
1227 GET_CONFIRMATION @var{description}
1230 @var{description}is displayed along with a Okay and Cancel
1231 button. Blanks must be percent escaped or replaced by @code{+}. A
1232 @code{X} may be used to display confirmation dialog with a default
1235 The agent either returns with an error or with a OK. Note, that the
1236 length of @var{description} is implicitly limited by the maximum
1237 length of a command.
1242 @subsection Check whether a key is available
1244 This can be used to see whether a secret key is available. It does
1245 not return any information on whether the key is somehow protected.
1248 HAVEKEY @var{keygrips}
1251 The agent answers either with OK or @code{No_Secret_Key} (208). The
1252 caller may want to check for other error codes as well. More than one
1253 keygrip may be given. In this case the command returns success if at
1254 least one of the keygrips corresponds to an available secret key.
1258 @subsection Register a smartcard
1264 This command is used to register a smartcard. With the --send
1265 option given the certificates are send back.
1269 @subsection Change a Passphrase
1272 PASSWD [--cache-nonce=<c>] [--passwd-nonce=<s>] [--preset] @var{keygrip}
1275 This command is used to interactively change the passphrase of the key
1276 identified by the hex string @var{keygrip}. The @option{--preset}
1277 option may be used to add the new passphrase to the cache using the
1278 default cache parameters.
1281 @node Agent UPDATESTARTUPTTY
1282 @subsection Change the standard display
1288 Set the startup TTY and X-DISPLAY variables to the values of this
1289 session. This command is useful to direct future pinentry invocations
1290 to another screen. It is only required because there is no way in the
1291 ssh-agent protocol to convey this information.
1294 @node Agent GETEVENTCOUNTER
1295 @subsection Get the Event Counters
1301 This function return one status line with the current values of the
1302 event counters. The event counters are useful to avoid polling by
1303 delaying a poll until something has changed. The values are decimal
1304 numbers in the range @code{0} to @code{UINT_MAX} and wrapping around to
1305 0. The actual values should not be relied upon; they shall only be used
1308 The currently defined counters are are:
1311 Incremented with any change of any of the other counters.
1313 Incremented for added or removed private keys.
1315 Incremented for changes of the card readers stati.
1319 @subsection Return information about the process
1321 This is a multipurpose function to return a variety of information.
1327 The value of @var{what} specifies the kind of information returned:
1330 Return the version of the program.
1332 Return the process id of the process.
1334 Return the name of the socket used to connect the agent.
1335 @item ssh_socket_name
1336 Return the name of the socket used for SSH connections. If SSH support
1337 has not been enabled the error @code{GPG_ERR_NO_DATA} will be returned.
1341 @subsection Set options for the session
1343 Here is a list of session options which are not yet described with
1344 other commands. The general syntax for an Assuan option is:
1347 OPTION @var{key}=@var{value}
1351 Supported @var{key}s are:
1354 @item agent-awareness
1355 This may be used to tell gpg-agent of which gpg-agent version the
1356 client is aware of. gpg-agent uses this information to enable
1357 features which might break older clients.
1360 Change the session's environment to be used for the
1361 Pinentry. Valid values are:
1365 Delete envvar @var{name}
1367 Set envvar @var{name} to the empty string
1368 @item @var{name}=@var{value}
1369 Set envvar @var{name} to the string @var{value}.
1372 @item use-cache-for-signing
1373 See Assuan command @code{PKSIGN}.
1375 @item allow-pinentry-notify
1376 This does not need any value. It is used to enable the
1377 PINENTRY_LAUNCHED inquiry.
1380 This option is used to change the operation mode of the pinentry. The
1381 following values are defined:
1385 This is the default mode which pops up a pinentry as needed.
1388 Instead of popping up a pinentry, return the error code
1389 @code{GPG_ERR_CANCELED}.
1392 Instead of popping up a pinentry, return the error code
1393 @code{GPG_ERR_NO_PIN_ENTRY}.
1396 Use a loopback pinentry. This fakes a pinentry by using inquiries
1397 back to the caller to ask for a passphrase. This option may only be
1398 set if the agent has been configured for that.
1399 Use the @xref{option --allow-loopback-pinentry}.
1403 @item cache-ttl-opt-preset
1404 This option sets the cache TTL for new entries created by GENKEY and
1405 PASSWD commands when using the @option{--preset} option. It it is not
1406 used a default value is used.
1409 Instead of using the standard S2K count (which is computed on the
1410 fly), the given S2K count is used for new keys or when changing the
1411 passphrase of a key. Values below 65536 are considered to be 0. This
1412 option is valid for the entire session or until reset to 0. This
1413 option is useful if the key is later used on boxes which are either
1414 much slower or faster than the actual box.
1423 @command{gpg-connect-agent}(1),
1424 @command{scdaemon}(1)
1426 @include see-also-note.texi