gpg-agent man page on Archlinux

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

       gpg-agent - Secret key management for GnuPG

       gpg-agent [--homedir dir] [--options file] [options]
       gpg-agent [--homedir dir] [--options file] [options] --server
       gpg-agent  [--homedir  dir]  [--options	file] [options] --daemon [com‐

       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

	 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 ~/.profile or .bash_profile.  It is best not to run multi‐
       ple 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 information about the agent is written
       to a file in the HOME directory.	 Note that by running gpg-agent	 with‐
       out 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

       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:

	 export GPG_TTY

       It is important that this environment variable always reflects the out‐
       put of the tty command.	For W32 systems this option is not required.

       Please  make  sure  that	 a  proper pinentry program has been installed
       under the default filename (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	pinen‐
       try   (e.g.   ‘/usr/bin/pinentry-gtk’)	to   the  expected  one	 (e.g.

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

	      Print  the program version and licensing information.  Note that
	      you cannot abbreviate this command.


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

	      Print  a	list of all available options and commands.  Note that
	      you cannot abbreviate this command.

	      Run in server mode and wait for  commands	 on  the  stdin.   The
	      default  mode  is	 to  create  a	socket and listen for commands

       --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 commonly used to do this.  Yet another way is creat‐
	      ing a new process as a child of  gpg-agent:  gpg-agent  --daemon
	      /bin/sh.	This way you get a new shell with the environment set‐
	      up properly; if you exit from this shell,	 gpg-agent  terminates
	      as well.

       --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


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


	      Try to be as quiet as possible.

	      Don't  invoke  a	pinentry or do any other thing requiring human

       --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 keyword.

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

		     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

       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 currently 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

	      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.

	      Don't detach the process from the console.  This is mainly  use‐
	      ful for debugging.




       --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 cor‐
	      rect 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 available.  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

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

	      Tell  the	 pinentry  not	to  grab the keyboard and mouse.  This
	      option should  in	 general  not  be  used	 to  avoid  X-sniffing

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

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

	      This option will let gpg-agent bypass the passphrase  cache  for
	      all  signing  operation.	 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  sec‐
	      onds.  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

	      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 warn‐
	      ing 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.

	      This option does nothing yet.

       --pinentry-program filename
	      Use program filename as the PIN entry.  The default is installa‐
	      tion 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  dependent  and  can be shown with the gpgconf com‐

	      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.

	      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


	      By  enabling  this  option  gpg-agent  will listen on the socket
	      named ‘S.gpg-agent’, located in the home directory, and not cre‐
	      ate a random socket below a temporary directory.	Tools connect‐
	      ing 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 system which does not support spe‐
	      cial 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  configured  for  use
	      with the standard socket by issuing the command gpg-agent --use-
	      standard-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


	      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 the OpenSSH Agent protocol.

	      In this mode of operation, the agent does not only implement the
	      gpg-agent	 protocol, but also the agent protocol used by OpenSSH
	      (through a separate socket).  Consequently, it should be	possi‐
	      ble  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 neces‐
	      sary  for decrypting the stored key.  Since the ssh-agent proto‐
	      col 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 display  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 authenti‐
       cation.	To fix this you may start gpg-agent if needed using this  sim‐
       ple command:

	 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.

       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:


	 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

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

       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]).

		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 abbre‐
		This file is also read after a SIGHUP however only a few
		options	 will  actually have an effect.	 This default name may
		changed on the command line (see: [option --options]).
		You should backup this file.

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

		Comment	 lines,	 indicated  by a leading hash mark, as well as
		lines are ignored.  To mark a key as trusted you need to enter
		fingerprint  followed  by  a  space  and  a  capital letter S.
		may optionally be used to separate the bytes of a fingerprint;
		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
		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

       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

	      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.

	      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

	      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


		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]).

       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-sign‐
	      ing,  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.

	      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.

	      Dump internal information to the log file.

	      This signal is used for internal purposes.

       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

	 info gnupg

       should give you access to the complete manual including a  menu	struc‐
       ture and an index.

GnuPG 2.0.22			  2013-12-16			  GPG-AGENT(1)

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