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GPG-AGENT(1)				GNU Privacy Guard			     GPG-AGENT(1)

NAME
       gpg-agent - Secret key management for GnuPG

SYNOPSIS
       gpg-agent [--homedir dir] [--options file] [options]
       gpg-agent [--homedir dir] [--options file] [options] --server
       gpg-agent [--homedir dir] [--options file] [options] --daemon [command_line]

DESCRIPTION
       gpg-agent is a daemon to manage secret (private) keys independently from any protocol.  It
       is used as a backend for gpg and gpgsm as well as for a couple of other utilities.

       The agent is usualy started on demand by gpg, gpgsm, gpgconf or	gpg-connect-agent.   Thus
       there  is  no  reason  to  start it manually.  In case you want to use the included Secure
       Shell Agent you may start the agent using:

	 gpg-connect-agent /bye

       The usual way to run the agent is from the ~/.xsession file:

	 eval $(gpg-agent --daemon)

       If you don't use an X server, you can also put this into your regular startup file ~/.pro-
       file  or  .bash_profile.  It is best not to run multiple instance of the gpg-agent, so you
       should make sure that only one is running:  gpg-agent  uses  an	environment  variable  to
       inform clients about the communication parameters. You can write the content of this envi-
       ronment variable to a file so that you can test for a running agent.  Here is  an  example
       using Bourne shell syntax:

	 gpg-agent --daemon --enable-ssh-support \
		   --write-env-file "${HOME}/.gpg-agent-info"

       This code should only be run once per user session to initially fire up the agent.  In the
       example the optional support for the included Secure Shell agent is enabled and the infor-
       mation  about  the agent is written to a file in the HOME directory.  Note that by running
       gpg-agent without arguments you may test whether an agent is already running; however such
       a test may lead to a race condition, thus it is not suggested.

       The second script needs to be run for each interactive session:

	 if [ -f "${HOME}/.gpg-agent-info" ]; then
	   . "${HOME}/.gpg-agent-info"
	   export GPG_AGENT_INFO
	   export SSH_AUTH_SOCK
	 fi

       It  reads  the  data  out  of the file and exports the variables.  If you don't use Secure
       Shell, you don't need the last two export statements.

       You should always add the following lines to your .bashrc or whatever initialization  file
       is used for all shell invocations:

	 GPG_TTY=$(tty)
	 export GPG_TTY

       It  is important that this environment variable always reflects the output of the tty com-
       mand.  For W32 systems this option is not required.

       Please make sure that a proper pinentry program has been installed under the default file-
       name  (which  is  system dependant) or use the option pinentry-program to specify the full
       name of that program.  It is often useful to install a symbolic link from the actual  used
       pinentry (e.g. '/usr/bin/pinentry-gtk') to the expected one (e.g. '/usr/bin/pinentry').

COMMANDS
       Commands  are  not distinguished from options except for the fact that only one command is
       allowed.

       --version
	      Print the program version and licensing information.  Note that you cannot abbrevi-
	      ate this command.

       --help

       -h     Print  a usage message summarizing the most useful command-line options.	Note that
	      you cannot abbreviate this command.

       --dump-options
	      Print a list of all available options and commands.  Note that you cannot  abbrevi-
	      ate this command.

       --server
	      Run in server mode and wait for commands on the stdin.  The default mode is to cre-
	      ate a socket and listen for commands there.

       --daemon [command line]
	      Start the gpg-agent as a daemon; that is, detach it from the console and run it  in
	      the  background.	 Because  gpg-agent prints out important information required for
	      further use, a common way of invoking gpg-agent is: eval $(gpg-agent  --daemon)  to
	      setup  the  environment variables.  The option --write-env-file is another way com-
	      monly used to do this.  Yet another way is creating a new process  as  a	child  of
	      gpg-agent: gpg-agent --daemon /bin/sh.  This way you get a new shell with the envi-
	      ronment setup properly; if you exit from this shell, gpg-agent terminates as well.

OPTIONS
       --options file
	      Reads configuration from file instead of from the  default  per-user  configuration
	      file.  The default configuration file is named 'gpg-agent.conf' and expected in the
	      '.gnupg' directory directly below the home directory of the user.

       --homedir dir
	      Set the name of the home directory to dir. If this option is  not  used,	the  home
	      directory  defaults to '~/.gnupg'.  It is only recognized when given on the command
	      line.  It also overrides any home directory stated through the environment variable
	      'GNUPGHOME'  or  (on  W32  systems)  by  means  of  the  Registry  entry HKCU\Soft-
	      ware\GNU\GnuPG:HomeDir.

       -v

       --verbose
	      Outputs additional information while running.  You can increase  the  verbosity  by
	      giving several verbose commands to gpgsm, such as '-vv'.

       -q

       --quiet
	      Try to be as quiet as possible.

       --batch
	      Don't invoke a pinentry or do any other thing requiring human interaction.

       --faked-system-time epoch
	      This  option  is	only useful for testing; it sets the system time back or forth to
	      epoch which is the number of seconds elapsed since the year 1970.

       --debug-level level
	      Select the debug level for investigating problems. level may be a numeric value  or
	      a keyword:

	      none   No debugging at all.  A value of less than 1 may be used instead of the key-
		     word.

	      basic  Some basic debug messages.  A value between 1 and 2 may be used  instead  of
		     the keyword.

	      advanced
		     More verbose debug messages.  A value between 3 and 5 may be used instead of
		     the keyword.

	      expert Even more detailed messages.  A value between 6 and 8 may be used instead of
		     the keyword.

	      guru   All  of  the  debug messages you can get. A value greater than 8 may be used
		     instead of the keyword.  The creation of hash tracing files is only  enabled
		     if the keyword is used.

       How  these  messages  are  mapped  to  the actual debugging flags is not specified and may
       change with newer releases of this program. They are however carefully  selected  to  best
       aid in debugging.

       --debug flags
	      This  option  is only useful for debugging and the behaviour may change at any time
	      without notice.  FLAGS are bit encoded and may be given in usual C-Syntax. The cur-
	      rently defined bits are:

	      0 (1)  X.509 or OpenPGP protocol related data

	      1 (2)  values of big number integers

	      2 (4)  low level crypto operations

	      5 (32) memory allocation

	      6 (64) caching

	      7 (128)
		     show memory statistics.

	      9 (512)
		     write hashed data to files named dbgmd-000*

	      10 (1024)
		     trace Assuan protocol

	      12 (4096)
		     bypass all certificate validation

       --debug-all
	      Same as --debug=0xffffffff

       --debug-wait n
	      When  running  in server mode, wait n seconds before entering the actual processing
	      loop and print the pid.  This gives time to attach a debugger.

       --no-detach
	      Don't detach the process from the console.  This is mainly useful for debugging.

       -s

       --sh

       -c

       --csh  Format the info output in daemon mode for use with the standard Bourne shell or the
	      C-shell respectively.  The default is to guess it based on the environment variable
	      SHELL which is correct in almost all cases.

       --write-env-file file
	      Often it is required to connect to the agent from a process not being  an  inferior
	      of  gpg-agent  and thus the environment variable with the socket name is not avail-
	      able.  To help setting up those variables in other sessions,  this  option  may  be
	      used to write the information into file.	If file is not specified the default name
	      '${HOME}/.gpg-agent-info' will be used.  The format is suitable to be evaluated  by
	      a Bourne shell like in this simple example:

	 eval $(cat file)
	 eval $(cut -d= -f 1 < file | xargs echo export)

       --no-grab
	      Tell  the  pinentry not to grab the keyboard and mouse.  This option should in gen-
	      eral not be used to avoid X-sniffing attacks.

       --log-file file
	      Append all logging output to file.  This is very helpful in seeing what  the  agent
	      actually	does.	If neither a log file nor a log file descriptor has been set on a
	      Windows platform, the  Registry  entry  HKCU\Software\GNU\GnuPG:DefaultLogFile,  if
	      set, is used to specify the logging output.

       --allow-mark-trusted
	      Allow clients to mark keys as trusted, i.e. put them into the 'trustlist.txt' file.
	      This is by default not allowed to make it harder for users to inadvertently  accept
	      Root-CA keys.

       --allow-loopback-pinentry
	      Allow  clients  to use the loopback pinentry features; see the option pinentry-mode
	      for details.

       --ignore-cache-for-signing
	      This option will let gpg-agent bypass the passphrase cache for all  signing  opera-
	      tion.   Note  that there is also a per-session option to control this behaviour but
	      this command line option takes precedence.

       --default-cache-ttl n
	      Set the time a cache entry is valid to n seconds.  The default is 600 seconds.

       --default-cache-ttl-ssh n
	      Set the time a cache entry used for SSH keys is valid to n seconds.  The default is
	      1800 seconds.

       --max-cache-ttl n
	      Set  the maximum time a cache entry is valid to n seconds.  After this time a cache
	      entry will be expired even if it has been accessed  recently.   The  default  is	2
	      hours (7200 seconds).

       --max-cache-ttl-ssh n
	      Set  the maximum time a cache entry used for SSH keys is valid to n seconds.  After
	      this time a cache entry will be expired even if it has been accessed recently.  The
	      default is 2 hours (7200 seconds).

       --enforce-passphrase-constraints
	      Enforce  the  passphrase	constraints by not allowing the user to bypass them using
	      the ``Take it anyway'' button.

       --min-passphrase-len n
	      Set the minimal length of a passphrase.  When entering  a  new  passphrase  shorter
	      than this value a warning will be displayed.  Defaults to 8.

       --min-passphrase-nonalpha n
	      Set  the	minimal  number of digits or special characters required in a passphrase.
	      When entering a new passphrase with less than this  number  of  digits  or  special
	      characters a warning will be displayed.  Defaults to 1.

       --check-passphrase-pattern file
	      Check  the  passphrase  against  the  pattern  given  in file.  When entering a new
	      passphrase matching one of these pattern a warning will be displayed.  file  should
	      be an absolute filename.	The default is not to use any pattern file.

	      Security	note: It is known that checking a passphrase against a list of pattern or
	      even  against  a	complete  dictionary  is  not  very  effective	to  enforce  good
	      passphrases.   Users  will  soon	figure up ways to bypass such a policy.  A better
	      policy is to educate users on good  security  behavior  and  optionally  to  run	a
	      passphrase  cracker  regularly  on  all  users passphrases to catch the very simple
	      ones.

       --max-passphrase-days n
	      Ask the user to change the passphrase if n days have passed since the last  change.
	      With --enforce-passphrase-constraints set the user may not bypass this check.

       --enable-passphrase-history
	      This option does nothing yet.

       --pinentry-program filename
	      Use program filename as the PIN entry.  The default is installation dependent.

       --pinentry-touch-file filename
	      By default the filename of the socket gpg-agent is listening for requests is passed
	      to Pinentry, so that it can touch that file before exiting (it does  this  only  in
	      curses  mode).   This  option changes the file passed to Pinentry to filename.  The
	      special name /dev/null may be used to completely disable this feature.   Note  that
	      Pinentry will not create that file, it will only change the modification and access
	      time.

       --scdaemon-program filename
	      Use program filename as the Smartcard daemon.  The default is  installation  depen-
	      dent and can be shown with the gpgconf command.

       --disable-scdaemon
	      Do  not make use of the scdaemon tool.  This option has the effect of disabling the
	      ability to do smartcard operations.  Note, that enabling	this  option  at  runtime
	      does not kill an already forked scdaemon.

       --disable-check-own-socket
	      gpg-agent  employs  a  periodic  self-test to detect a stolen socket.  This usually
	      means a second instance of gpg-agent has taken over the socket and  gpg-agent  will
	      then  terminate  itself.	 This  option  may  be used to disable this self-test for
	      debugging purposes.

       --use-standard-socket

       --no-use-standard-socket
	      By enabling this option gpg-agent will listen on the  socket  named  'S.gpg-agent',
	      located  in  the	home  directory, and not create a random socket below a temporary
	      directory.  Tools connecting to gpg-agent should first try to connect to the socket
	      given  in  environment  variable	GPG_AGENT_INFO and then fall back to this socket.
	      This option may not be used if the home directory is mounted on a remote file  sys-
	      tem  which does not support special files like fifos or sockets.	Note, that --use-
	      standard-socket is the default on all systems since GnuPG 2.1.  Note,  that  --use-
	      standard-socket  is  the default on Windows systems.  The default may be changed at
	      build time.  It is possible to test at runtime whether the agent has  been  config-
	      ured  for use with the standard socket by issuing the command gpg-agent --use-stan-
	      dard-socket-p which returns success if the standard socket option has been enabled.

       --display string

       --ttyname string

       --ttytype string

       --lc-ctype string

       --lc-messages string

       --xauthority string
	      These options are used with the server mode to pass localization information.

       --keep-tty

       --keep-display
	      Ignore requests to change the current tty or X  window  system's	DISPLAY  variable
	      respectively.   This is useful to lock the pinentry to pop up at the tty or display
	      you started the agent.

       --enable-ssh-support

	      Enable the OpenSSH Agent protocol.

	      In this mode of operation, the agent does not only implement the	gpg-agent  proto-
	      col, but also the agent protocol used by OpenSSH (through a separate socket).  Con-
	      sequently, it should be possible to use the gpg-agent as a drop-in replacement  for
	      the well known ssh-agent.

	      SSH Keys, which are to be used through the agent, need to be added to the gpg-agent
	      initially through the ssh-add utility.  When a key is added, ssh-add will  ask  for
	      the  password of the provided key file and send the unprotected key material to the
	      agent; this causes the gpg-agent to ask for a passphrase, which is to be	used  for
	      encrypting the newly received key and storing it in a gpg-agent specific directory.

	      Once a key has been added to the gpg-agent this way, the gpg-agent will be ready to
	      use the key.

	      Note: in case the gpg-agent receives a signature request, the user might need to be
	      prompted for a passphrase, which is necessary for decrypting the stored key.  Since
	      the ssh-agent protocol does not contain a mechanism for telling the agent on  which
	      display/terminal	it is running, gpg-agent's ssh-support will use the TTY or X dis-
	      play where gpg-agent has been started.  To switch this display to the current  one,
	      the following command may be used:

	 gpg-connect-agent updatestartuptty /bye

       Although  all  GnuPG components try to start the gpg-agent as needed, this is not possible
       for the ssh support because ssh does not know about it.	 Thus  if  no  GnuPG  tool  which
       accesses  the agent has been run, there is no guarantee that ssh is abale to use gpg-agent
       for authentication.  To fix this you may start gpg-agent if needed using this simple  com-
       mand:

	 gpg-connect-agent /bye

       Adding the --verbose shows the progress of starting the agent.

       All  the  long options may also be given in the configuration file after stripping off the
       two leading dashes.

EXAMPLES
       The usual way to invoke gpg-agent is

	 $ eval $(gpg-agent --daemon)

       An alternative way is by replacing ssh-agent with gpg-agent.  If for example ssh-agent  is
       started	as  part  of  the  Xsession initialization, you may simply replace ssh-agent by a
       script like:

	 #!/bin/sh

	 exec /usr/local/bin/gpg-agent --enable-ssh-support --daemon \
	       --write-env-file ${HOME}/.gpg-agent-info "$@"

       and add something like (for Bourne shells)

	   if [ -f "${HOME}/.gpg-agent-info" ]; then
	     . "${HOME}/.gpg-agent-info"
	     export GPG_AGENT_INFO
	     export SSH_AUTH_SOCK
	   fi

       to your shell initialization file (e.g. '~/.bashrc').

FILES
       There are a few configuration files needed for the operation of the agent. By default they
       may all be found in the current home directory (see: [option --homedir]).

       gpg-agent.conf
		This is the standard configuration file read by gpg-agent on
		startup.  It may contain any valid long option; the leading
		two dashes may not be entered and the option may not be abbreviated.
		This file is also read after a SIGHUP however only a few
		options will actually have an effect.  This default name may be
		changed on the command line (see: [option --options]).
		You should backup this file.

       trustlist.txt
		This is the list of trusted keys.  You should backup this file.

		Comment lines, indicated by a leading hash mark, as well as empty
		lines are ignored.  To mark a key as trusted you need to enter its
		fingerprint followed by a space and a capital letter S.  Colons
		may optionally be used to separate the bytes of a fingerprint; this
		allows to cut and paste the fingerprint from a key listing output.  If
		the line is prefixed with a ! the key is explicitly marked as
		not trusted.

		Here is an example where two keys are marked as ultimately trusted
		and one as not trusted:

		.RS 2
		# CN=Wurzel ZS 3,O=Intevation GmbH,C=DE
		A6935DD34EF3087973C706FC311AA2CCF733765B S

		# CN=PCA-1-Verwaltung-02/O=PKI-1-Verwaltung/C=DE
		DC:BD:69:25:48:BD:BB:7E:31:6E:BB:80:D3:00:80:35:D4:F8:A6:CD S

		# CN=Root-CA/O=Schlapphuete/L=Pullach/C=DE
		!14:56:98:D3:FE:9C:CA:5A:31:6E:BC:81:D3:11:4E:00:90:A3:44:C2 S
		.fi

       Before entering a key into this file, you need to ensure its
       authenticity.  How to do this depends on your organisation; your
       administrator might have already entered those keys which are deemed
       trustworthy enough into this file.  Places where to look for the
       fingerprint of a root certificate are letters received from the CA or
       the website of the CA (after making 100% sure that this is indeed the
       website of that CA).  You may want to consider allowing interactive
       updates of this file by using the see: [option --allow-mark-trusted].
       This is however not as secure as maintaining this file manually.  It is
       even advisable to change the permissions to read-only so that this file
       can't be changed inadvertently.

       As a special feature a line include-default will include a global
       list of trusted certificates (e.g. '/etc/gnupg/trustlist.txt').
       This global list is also used if the local list is not available.

       It is possible to add further flags after the S for use by the
       caller:

	      relax  Relax checking of some root certificate requirements.  As of now this
		     flag allows the use of root certificates with a missing basicConstraints
		     attribute (despite that it is a MUST for CA certificates) and disables
		     CRL checking for the root certificate.

	      cm     If validation of a certificate finally issued by a CA with this flag set
		     fails, try again using the chain validation model.

       sshcontrol
	      This file is used when support for the secure shell agent protocol has
	      been enabled (see: [option --enable-ssh-support]). Only keys present in
	      this file are used in the SSH protocol.  You should backup this file.

	      The ssh-add tool may be used to add new entries to this file;
	      you may also add them manually.  Comment lines, indicated by a leading
	      hash mark, as well as empty lines are ignored.  An entry starts with
	      optional whitespace, followed by the keygrip of the key given as 40 hex
	      digits, optionally followed by the caching TTL in seconds and another
	      optional field for arbitrary flags.  A non-zero TTL overrides the global
	      default as set by --default-cache-ttl-ssh.

	      The only flag support is confirm.  If this flag is found for a
	      key, each use of the key will pop up a pinentry to confirm the use of
	      that key.  The flag is automatically set if a new key was loaded into
	      gpg-agent using the option -c of the ssh-add
	      command.

	      The keygrip may be prefixed with a ! to disable an entry entry.

	      The following example lists exactly one key.  Note that keys available
	      through a OpenPGP smartcard in the active smartcard reader are
	      implicitly added to this list; i.e. there is no need to list them.

		.RS 2
		# Key added on: 2011-07-20 20:38:46
		# Fingerprint:	5e:8d:c4:ad:e7:af:6e:27:8a:d6:13:e4:79:ad:0b:81
		34B62F25E277CF13D3C6BCEBFD3F85D08F0A864B 0 confirm
		.fi

       private-keys-v1.d/

		This is the directory where gpg-agent stores the private keys.	Each
		key is stored in a file with the name made up of the keygrip and the
		suffix 'key'.  You should backup all files in this directory
		and take great care to keep this backup closed away.

	      Note that on larger installations, it is useful to put predefined
	      files into the directory '/etc/skel/.gnupg/' so that newly created
	      users start up with a working configuration.  For existing users the
	      a small helper script is provided to create these files (see: [addgnupghome]).

SIGNALS
       A  running  gpg-agent  may be controlled by signals, i.e. using the kill command to send a
       signal to the process.

       Here is a list of supported signals:

       SIGHUP This signal flushes all cached passphrases and if the program has been started with
	      a  configuration	file, the configuration file is read again.  Only certain options
	      are honored: quiet, verbose, debug, debug-all, debug-level, no-grab,  pinentry-pro-
	      gram,   default-cache-ttl,   max-cache-ttl,  ignore-cache-for-signing,  allow-mark-
	      trusted, disable-scdaemon, and disable-check-own-socket.	scdaemon-program is  also
	      supported  but  due  to  the  current implementation, which calls the scdaemon only
	      once, it is not of much use unless you manually kill the scdaemon.

       SIGTERM
	      Shuts down the process but waits until all current requests are fulfilled.  If  the
	      process  has received 3 of these signals and requests are still pending, a shutdown
	      is forced.

       SIGINT Shuts down the process immediately.

       SIGUSR1
	      Dump internal information to the log file.

       SIGUSR2
	      This signal is used for internal purposes.

SEE ALSO
       gpg2(1), gpgsm(1), gpg-connect-agent(1), scdaemon(1)

       The full documentation for this tool is maintained as a Texinfo manual.	If GnuPG and  the
       info program are properly installed at your site, the command

	 info gnupg

       should give you access to the complete manual including a menu structure and an index.

GnuPG 2.0.22				    2014-06-10				     GPG-AGENT(1)
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