gpg-agent(glossar.html) - phpMan

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

NAME
       gpg-agent - Secret key management for GnuPG
SYNOPSIS
       gpg-agent [--homedir dir] [--options file] [options]
       gpg-agent [--homedir dir] [--options file] [options] --server
       gpg-agent  [--homedir  dir]  [--options  file] [options] --daemon [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 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 $(gpg-agent --daemon)
       If  you  don't use an X server, you can also put this into your regular
       startup file ~/.profile or .bash_profile.  It is best not to run multi-
       ple instance of the gpg-agent, so you should make sure that only one is
       running: gpg-agent uses an environment variable to inform clients about
       the  communication  parameters. You can write the content of this envi-
       ronment variable to a file so that you can test for  a  running  agent.
       Here is an example using Bourne shell syntax:
         gpg-agent --daemon --enable-ssh-support \
                   --write-env-file "${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
         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 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.
       `/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 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
       --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  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.

       --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 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-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  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
              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-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-
              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
              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
              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  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.

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 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
                allows  to  cut  and  paste the fingerprint from a key listing
              output.  If
                the line is prefixed with a ! the key is explicitly marked as
                not trusted.
                Here is an example where two keys  are  marked  as  ultimately
              trusted
                and one as not trusted:
                .RS 2
                # CN=Wurzel ZS 3,O=Intevation GmbH,C=DE
                A6935DD34EF3087973C706FC311AA2CCF733765B S
                # CN=PCA-1-Verwaltung-02/O=PKI-1-Verwaltung/C=DE
                DC:BD:69:25:48:BD:BB:7E:31:6E:BB:80:D3:00:80:35:D4:F8:A6:CD S
                # CN=Root-CA/O=Schlapphuete/L=Pullach/C=DE
                !14:56:98:D3:FE:9C:CA:5A:31:6E:BC:81:D3:11:4E:00:90:A3:44:C2 S
                .fi
       Before entering a key into this file, you need to ensure its
       authenticity.  How to do this depends on your organisation; your
       administrator might have already entered those keys which are deemed
       trustworthy enough into this file.  Places where to look for the
       fingerprint of a root certificate are letters received from the CA or
       the website of the CA (after making 100% sure that this is indeed the
       website of that CA).  You may want to consider allowing interactive
       updates of this file by using the see: [option --allow-mark-trusted].
       This is however not as secure as maintaining this file manually.  It is
       even advisable to change the permissions to read-only so that this file
       can't be changed inadvertently.
       As a special feature a line include-default will include a global
       list of trusted certificates (e.g. `/etc/gnupg/trustlist.txt').
       This global list is also used if the local list is not available.
       It is possible to add further flags after the S for use by the
       caller:

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

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


       sshcontrol
              This file is used when support for the secure shell agent protocol has
              been enabled (see: [option --enable-ssh-support]). Only keys present in
              this file are used in the SSH protocol.  You should backup this file.
              The ssh-add tool may be used to add new entries to this file;
              you may also add them manually.  Comment lines, indicated by a leading
              hash mark, as well as empty lines are ignored.  An entry starts with
              optional whitespace, followed by the keygrip of the key given as 40 hex
              digits, optionally followed by the caching TTL in seconds and another
              optional field for arbitrary flags.  A non-zero TTL overrides the global
              default as set by --default-cache-ttl-ssh.
              The only flag support is confirm.  If this flag is found for a
              key, each use of the key will pop up a pinentry to confirm the use of
              that key.  The flag is automatically set if a new key was loaded into
              gpg-agent using the option -c of the ssh-add
              command.
              The keygrip may be prefixed with a ! to disable an entry entry.
              The following example lists exactly one key.  Note that keys available
              through a OpenPGP smartcard in the active smartcard reader are
              implicitly added to this list; i.e. there is no need to list them.
                .RS 2
                # Key added on: 2011-07-20 20:38:46
                # Fingerprint:  5e:8d:c4:ad:e7:af:6e:27:8a:d6:13:e4:79:ad:0b:81
                34B62F25E277CF13D3C6BCEBFD3F85D08F0A864B 0 confirm
                .fi

       private-keys-v1.d/
                This is the directory where gpg-agent stores the private keys.  Each
                key is stored in a file with the name made up of the keygrip and the
                suffix `key'.  You should backup all files in this directory
                and take great care to keep this backup closed away.

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


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

       SIGHUP This signal flushes all cached passphrases and  if  the  program
              has  been  started  with a configuration file, the configuration
              file is read again.  Only certain options  are  honored:  quiet,
              verbose,  debug,  debug-all, debug-level, no-grab, pinentry-pro-
              gram, default-cache-ttl,  max-cache-ttl,  ignore-cache-for-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.

       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  struc-
       ture and an index.

GnuPG 2.0.22                      2018-07-13                      GPG-AGENT(1)