gpg-agent(1)



GPG-AGENT(1)                 GNU Privacy Guard 2.1                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 [com-
       mand_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 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

       If  you want to manually terminate the currently-running agent, you can
       safely do so with:

         gpgconf --kill gpg-agent

       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 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 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 pinen-
       try  (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 abbreviate 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 abbreviate this command.

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

              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.

       --supervised
              Run  in  the  foreground, sending logs by default to stderr, and
              listening on provided file descriptors, which  must  already  be
              bound to listening sockets.  This command is useful when running
              under systemd or  other  similar  process  supervision  schemes.
              This option is not supported on Windows.

              In --supervised mode, different file descriptors can be provided
              for use as different socket types (e.g. ssh, extra) as  long  as
              they  are  identified in the environment variable LISTEN_FDNAMES
              (see sd_listen_fds(3)  on  some  Linux  distributions  for  more
              information on this convention).

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 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 con-
              sidered, all other ways to set a home directory are ignored.

              To install GnuPG as a portable application under Windows, create
              an empty file named 'gpgconf.ctl' in the same directory  as  the
              tool  'gpgconf.exe'.   The root of the installation is then 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.

       -v

       --verbose
              Outputs additional information while running.  You can  increase
              the  verbosity  by giving several verbose commands to gpg-agent,
              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 keyword.

              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 behavior 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

       --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.

       --debug-quick-random
              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 pack-
              age.  It can be run as follows: 'sudo rngd -f -r /dev/urandom'.

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

       --no-detach
              Don't detach the process from the console.  This is mainly  use-
              ful 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 cor-
              rect in almost all cases.

       --grab
       --no-grab
              Tell the pinentry to grab the keyboard and mouse.   This  option
              should be used on X-Servers to avoid X-sniffing attacks. Any use
              of the option --grab overrides an used  option  --no-grab.   The
              default is --no-grab.

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

       --no-allow-mark-trusted
              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.

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

       --no-allow-loopback-pinentry

       --allow-loopback-pinentry
              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 con-
              trolled  by  this  option:  The  option is ignored if a loopback
              pinentry is disallowed.

       --no-allow-external-cache
              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
              passphrase.

       --allow-emacs-pinentry
              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.

       --ignore-cache-for-signing
              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 behavior 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
              max-cache-ttl.

       --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.  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-pre-
              set-passphrase.  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  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.

       --enable-passphrase-history
              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 Pinen-
              try 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
              request.

       --pinentry-program filename
              Use program filename as the PIN entry.  The default is installa-
              tion  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\bin\pinentry.exe',        '..\Gpg4win\pinentry.exe',
              '..\GNU\GnuPG\pinentry.exe',          '..\GNU\bin\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 com-
              mand.

       --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
       --use-standard-socket-p
              Since  GnuPG  2.1  the  standard  socket  is always used.  These
              options have no more effect.  The command gpg-agent  --use-stan-
              dard-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
              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.

       --extra-socket name
              The extra socket is created by default, you may use this  option
              to  change  the  name of the socket.  To disable the creation of
              the socket use ``none'' or ``/dev/null'' for 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-extended-key-format
              This option creates keys in the  extended  private  key  format.
              Changing  the  passphrase  of a key will also convert the key to
              that new format.  Using  this  option  makes  the  private  keys
              unreadable  for gpg-agent versions before 2.1.12.  The advantage
              of the extended private key format is that it is text based  and
              can  carry  additional  meta  data.   Note that this option also
              changes the key protection format to use OCB mode.

       --enable-ssh-support
       --enable-putty-support

              The OpenSSH Agent protocol is always enabled, but gpg-agent will
              only set the SSH_AUTH_SOCK variable if this flag is given.

              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 able to use gpg-agent for authentica-
       tion.   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 simi-
       lar to the regular ssh-agent support but makes use of  Windows  message
       queue as required by putty.

       --ssh-fingerprint-digest

              Select  the  digest  algorithm  used to compute ssh fingerprints
              that are communicated to the user,  e.g.  in  pinentry  dialogs.
              OpenSSH  has  transitioned  from  using  MD5  to the more secure
              SHA256.

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

EXAMPLES
       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)"
         fi

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 abbre-
              viated.
                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
                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
              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 disallowing interactive
       updates of this file by using the [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
       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.

              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

       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, 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.

       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
       gpg(1), gpgsm(1), gpgconf(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  struc-
       ture and an index.

GnuPG 2.2.1                       2017-09-18                      GPG-AGENT(1)

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