Options may either be used on the command line or, after stripping off the two leading dashes, in the configuration 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. This option is ignored if used in an options file.
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
(on Windows systems) by means of the Registry entry
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 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 ROOTAPPDATA/GNU/cache/gnupg for internal cache files.
Outputs additional information while running.
You can increase the verbosity by giving several
verbose commands to
gpg-agent, such as ‘-vv’.
Try to be as quiet as possible.
Don’t invoke a pinentry or do any other thing requiring human interaction.
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.
Select the debug level for investigating problems. level may be a numeric value or a keyword:
No debugging at all. A value of less than 1 may be used instead of the keyword.
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.
Even more detailed messages. A value between 6 and 8 may be used instead of the keyword.
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.
Set debug flags. All flags are or-ed and flags may be given in C syntax (e.g. 0x0042) or as a comma separated list of flag names. To get a list of all supported flags the single word "help" can be used. This option is only useful for debugging and the behavior may change at any time without notice.
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
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
rngd is typically provided by the
rng-tools package. It can be run as follows: ‘sudo
rngd -f -r /dev/urandom’.
This option enables extra debug information pertaining to the
Pinentry. As of now it is only useful when used along with
Don’t detach the process from the console. This is mainly useful for debugging.
In --daemon mode, gpg-agent detects an already running gpg-agent and does not allow to start a new instance. This option can be used to override this check: the new gpg-agent process will try to take over the communication sockets from the already running process and start anyway. This option should in general not be used.
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
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.
Append all logging output to file. This is very helpful in
seeing 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\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.
Entirely ignore the user trust list and consider only the global trustlist (APPDATA/GNU/etc/gnupg/trustlist.txt). This implies the option --no-allow-mark-trusted.
Changes the default name for the global trustlist from "trustlist.txt" to file. If file does not contain any slashes and does not start with "~/" it is searched in the system configuration directory (APPDATA/GNU/etc/gnupg).
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
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 passphrase.
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 behavior but this command line option takes precedence.
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. Note that a cached passphrase may not be
evicted immediately from memory if no client requests a cache
operation. This is due to an internal housekeeping function which is
only run every few seconds.
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
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
default is 2 hours (7200 seconds).
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
Enforce the passphrase constraints by not allowing the user to bypass them using the “Take it anyway” button.
Set the minimal length of a passphrase. When entering a new passphrase shorter than this value a warning will be displayed. Defaults to 8.
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 the passphrase against the pattern given in file. When entering a new passphrase matching one of these pattern a warning will be displayed. If file does not contain any slashes and does not start with "~/" it is searched in the system configuration directory (APPDATA/GNU/etc/gnupg). The default is not to use any pattern file. The second version of this option is only used when creating a new symmetric key to allow the use of different patterns for such passphrases.
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.
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.
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.
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.
This option asks the Pinentry to enable passphrase formatting when asking the user for a new passphrase and masking of the passphrase is turned off.
If passphrase formatting is enabled, then all non-breaking space characters are stripped from the entered passphrase. Passphrase formatting is mostly useful in combination with passphrases generated with the GENPIN feature of some Pinentries. Note that such a generated passphrase, if not modified by the user, skips all passphrase constraints checking because such constraints would actually weaken the generated passphrase.
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\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.
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.
Use program filename as the Smartcard daemon. The default is
installation dependent and can be shown with the
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
has taken over the socket and
gpg-agent will then terminate
itself. This option may be used to disable this self-test for
Since GnuPG 2.1 the standard socket is always used. These options
have no more effect. The command
--use-standard-socket-p will thus always return success.
These options are used with the server mode to pass localization information.
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.
Set the size of the queue for pending connections. The default is 64.
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.
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
These options are obsolete and have no effect. The extended key format is used for years now and has been supported since 2.1.12. Existing keys in the old format are migrated to the new format as soon as they are touched.
The OpenSSH Agent protocol is always enabled, but
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 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:
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
The order in which keys are presented to ssh are:
Negative Use-for-ssh values
If a key file has the attribute "Use-for-ssh" and its value is negative, these keys are presented first to ssh. The negative values are capped at -999 with -999 beeing lower ranked than -1. These values can be used to prefer on-disk keys over keys taken from active cards.
Active cards (inserted into a card reader or plugged in tokens) are always tried; they are ordered by their serial numbers.
Keys listed in the sshcontrol file
Non-disabled keys from the sshcontrol file are presented in the order they appear in this file. Note that the sshcontrol file is deprecated.
Positive Use-for-ssh values
If a key file has the attribute "Use-for-ssh" and its value is "yes", "true", or any positive number the key is presented in the order of their values. "yes" and "true" have a value of 1; other values are capped at 99999.
Editing the "Use-for-ssh" values can be done with an editor or using
gpg-connect-agent and "KEYATTR" (Remember to append a colon
to the key; i.e. use "Use-for-ssh:").
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.
Allow Libgcrypt to expand its secure memory area as required. The optional value n is a non-negative integer with a suggested size in bytes of each additionally allocated secure memory area. The value is rounded up to the next 32 KiB; usual C style prefixes are allowed. For an heavy loaded gpg-agent with many concurrent connection this option avoids sign or decrypt errors due to out of secure memory error returns.
Change the default calibration time to milliseconds. The given
value is capped at 60 seconds; a value of 0 resets to the compiled-in
default. This option is re-read on a SIGHUP (or
--reload gpg-agent) and the S2K count is then re-calibrated.
Specify the iteration count used to protect the passphrase. This option can be used to override the auto-calibration done by default. The auto-calibration computes a count which requires by default 100ms to mangle a given passphrase. See also --s2k-calibration.
To view the actually used iteration count and the milliseconds required for an S2K operation use:
gpg-connect-agent 'GETINFO s2k_count' /bye gpg-connect-agent 'GETINFO s2k_time' /bye
To view the auto-calibrated count use:
gpg-connect-agent 'GETINFO s2k_count_cal' /bye