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


   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 automatically 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

   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
   output  of  the  tty  command.   For  W32  systems  this  option is not

   Please make sure that a proper  pinentry  program  has  been  installed
   under  the  default  filename  (which  is  system dependent) 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.


   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.

          As an alternative you may create a new process  as  a  child  of
          gpg-agent:  gpg-agent  --daemon /bin/sh.  This way you get a new
          shell with the environment setup properly; after you  exit  from
          this shell, gpg-agent terminates within a few seconds.


   --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 Windows systems) by  means  of  the  Registry
          entry HKCU\Software\GNU\GnuPG:HomeDir.

          On Windows systems it is possible to install GnuPG as a portable
          application.  In this case only  this  command  line  option  is
          considered, all other ways to set a home directory are ignored.

          To install GnuPG as a portable application under Windows, create
          an empty file name 'gpgconf.ctl' in the same  directory  as  the
          tool  'gpgconf.exe'.   The root of the installation is than that
          directory; or, if  'gpgconf.exe'  has  been  installed  directly
          below  a  directory named 'bin', its parent directory.  You also
          need to make sure that the following directories exist  and  are
          writable:     'ROOT/home'     for    the    GnuPG    home    and
          'ROOT/var/cache/gnupg' for internal cache files.


          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.

          This  option  inhibits the use of the very secure random quality
          level (Libgcrypt's  GCRY_VERY_STRONG_RANDOM)  and  degrades  all
          request  down  to  standard random quality.  It is only used for
          testing and should not be used for any production quality  keys.
          This option is only effective when given on the command line.

          On  GNU/Linux,  another way to quickly generate insecure keys is
          to use rngd to fill the kernel's entropy pool with lower quality
          random  data.   rngd  is  typically  provided  by  the rng-tools
          package.   It  can  be  run  as  follows:  'sudo  rngd   -f   -r

          This  option  enables  extra debug information pertaining to the
          Pinentry.  As of now it is only  useful  when  used  along  with
          --debug 1024.

          Don't  detach  the  process  from  the  console.  This is mainly
          useful 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
          correct in almost all cases.

          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
          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.

          Do not allow clients to mark keys as trusted, i.e. put them into
          the 'trustlist.txt' file.  This makes it  harder  for  users  to
          inadvertently accept Root-CA keys.

          This  option allows the use of gpg-preset-passphrase to seed the
          internal cache of gpg-agent with passphrases.


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

          The  --force  option  of  the  Assuan command DELETE_KEY is also
          controlled by this option: The option is ignored if  a  loopback
          pinentry is disallowed.

          Tell Pinentry not to enable features which use an external cache
          for passphrases.

          Some desktop environments prefer to unlock all credentials  with
          one  master  password  and  may  have installed a Pinentry which
          employs an additional external cache to implement such a policy.
          By  using this option the Pinentry is advised not to make use of
          such a cache and instead always ask the user for  the  requested

          Tell  Pinentry  to allow features to divert the passphrase entry
          to a running  Emacs  instance.   How  this  is  exactly  handled
          depends on the version of the used Pinentry.

          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.   Each  time  a  cache  entry is accessed, the
          entry's timer is reset.  To set an entry's maximum lifetime, use

   --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.  Each time a cache  entry
          is  accessed,  the  entry's  timer  is reset.  To set an entry's
          maximum lifetime, use max-cache-ttl-ssh.

   --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 or has been set  using  gpg-preset-passphrase.
          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 or has been set using gpg-
          preset-passphrase.  The default is 2 hours (7200 seconds).

          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.

          This option does nothing yet.

   --pinentry-invisible-char char
          This  option asks the Pinentry to use char for displaying hidden
          characters.   char  must  be  one  character  UTF-8  string.   A
          Pinentry may or may not honor this request.

   --pinentry-timeout n
          This option asks the Pinentry to timeout after n seconds with no
          user input.  The default value of 0 does not ask the pinentry to
          timeout,  however  a  Pinentry  may  use its own default timeout
          value in this case.  A  Pinentry  may  or  may  not  honor  this

   --pinentry-program filename
          Use   program  filename  as  the  PIN  entry.   The  default  is
          installation dependent.  With the default configuration the name
          of  the  default  pinentry  is 'pinentry'; if that file does not
          exist but a 'pinentry-basic' exist the latter is used.

          On a Windows platform the default is to use the  first  existing
          program       from      this      list:      'bin\pinentry.exe',
          '..\Gpg4win	in\pinentry.exe',        '..\Gpg4win\pinentry.exe',
          '..\GNU\GnuPG\pinentry.exe',          '..\GNU	in\pinentry.exe',
          'bin\pinentry-basic.exe' where the file names  are  relative  to
          the GnuPG installation directory.

   --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

          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

          Since GnuPG 2.1 the  standard  socket  is  always  used.   These
          options  have  no  more  effect.   The  command gpg-agent --use-
          standard-socket-p will thus always return success.

   --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.

   --extra-socket name
          Also listen on native gpg-agent connections on the given socket.
          The intended use for this extra socket is to setup a Unix domain
          socket  forwarding  from  a remote machine to this socket on the
          local machine.  A gpg running on the  remote  machine  may  then
          connect  to  the local gpg-agent and use its private keys.  This
          enables decrypting or signing data on a remote  machine  without
          exposing the private keys to the remote machine.


          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
          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 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  able  to  use  gpg-agent   for
   authentication.   To  fix  this you may start gpg-agent if needed using
   this simple command:

     gpg-connect-agent /bye

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

   The --enable-putty-support is only available under Windows  and  allows
   the  use  of  gpg-agent  with  the  ssh  implementation putty.  This is
   similar to the regular ssh-agent  support  but  makes  use  of  Windows
   message queue as required by putty.

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


   It is important to set the environment variable GPG_TTY in  your  login
   shell, for example in the '~/.bashrc' init script:

       export GPG_TTY=$(tty)

   If  you  enabled the Ssh Agent Support, you also need to tell ssh about
   it by adding this to your init script:

     unset SSH_AGENT_PID
     if [ "${gnupg_SSH_AUTH_SOCK_by:-0}" -ne $$ ]; then
       export SSH_AUTH_SOCK="$(gpgconf --list-dirs agent-ssh-socket)"


   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
            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;
            enables cutting and pasting 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 disallowing interactive
   updates of this file by using the see: [option --no-allow-mark-trusted].
   It might even be 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.

            # 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.
            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, debug-pinentry, no-grab,
          pinentry-program,   pinentry-invisible-char,  default-cache-ttl,
          max-cache-ttl,   ignore-cache-for-signing,    no-allow-external-
          cache,   allow-emacs-pinentry,  no-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
   structure and an index.


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