Provided by: gnupg-agent_2.0.22-3ubuntu1_amd64 bug

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
       ~/.profile 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
       environment 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 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
       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    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
              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.  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 creating 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;  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\Software\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
                     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 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

       --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
              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 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
              general 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
              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 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
              dependent 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
              system  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  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 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
              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 abale 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.

       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-
              program, 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.