# phpman > man > gpg-agent(1) [GPG-AGENT(1)](https://www.chedong.com/phpMan.php/man/GPG-AGENT/1/markdown) GNU Privacy Guard 2.2 [GPG-AGENT(1)](https://www.chedong.com/phpMan.php/man/GPG-AGENT/1/markdown) ## 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 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 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 dependent) or use the option **pinentry-program** to specify the full name of that program. It is often useful to install a symbolic link from the actual used pinentry (e.g. ‘_/usr/bin/pinentry-gtk_’) to the expected one (e.g. ‘_/usr/bin/pinentry_’). ## COMMANDS Commands are not distinguished from options except for the fact that only one command is al‐ lowed. ### --version Print the program version and licensing information. Note that you cannot abbreviate this command. ### --help ### -h 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 vari‐ able **LISTEN**___**FDNAMES** (see [sd_listen_fds(3)](https://www.chedong.com/phpMan.php/man/sdlistenfds/3/markdown) on some Linux distributions for more infor‐ mation on this convention). ## OPTIONS Options may either be used on the command line or, after stripping off the two leading dashes, in the configuration file. **--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. This option is ignored if used in an options file. **--homedir** _dir_ Set the name of the home directory to _dir_. If this option is not used, the home direc‐ tory 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\Soft__‐ _ware\GNU\GnuPG:HomeDir_. On Windows systems it is possible to install GnuPG as a portable application. In this case only this command line option is considered, all other ways to set a home direc‐ tory 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 in‐ stallation 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 giv‐ ing 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 key‐ word. **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 in‐ stead 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 de‐ bugging. **--debug** _flags_ This option is only useful for debugging and the behavior may change at any time with‐ out 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** package. 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 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. ### --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 seeing what the agent ac‐ tually 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 **pinen**‐‐ **try-mode** for details. Allow is the default. The **--force** option of the Assuan command **DELETE**___**KEY** is also controlled by this option: The option is ignored if a loopback pinentry is disallowed. ### --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 imple‐ ment 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 in‐ stance. 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**. Note that a cached passphrase may not be evicted immedi‐ ately from memory if no client requests a cache operation. This is due to an internal housekeeping function which is only run every few 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. 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 en‐ try will be expired even if it has been accessed recently or has been set using **gpg-** **preset-passphrase**. The default is 2 hours (7200 seconds). **--max-cache-ttl-ssh** _n_ Set the maximum time a cache entry used for SSH keys is valid to _n_ seconds. After this time a cache entry will be expired even if it has been accessed recently or has been set using **gpg-preset-passphrase**. The default is 2 hours (7200 seconds). ### --enforce-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-invisible-char** _char_ This option asks the Pinentry to use _char_ for displaying hidden characters. _char_ must be one character UTF-8 string. A Pinentry may or may not honor this request. **--pinentry-timeout** _n_ This option asks the Pinentry to timeout after _n_ seconds with no user input. The de‐ fault 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 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. **--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 ter‐ minate itself. This option may be used to disable this self-test for debugging pur‐ poses. ### --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 ef‐ fect. The command **gpg-agent** **--use-standard-socket-p** will thus always return success. **--display** _string_ **--ttyname** _string_ **--ttytype** _string_ **--lc-ctype** _string_ **--lc-messages** _string_ **--xauthority** _string_ These options are used with the server mode to pass localization information. ### --keep-tty ### --keep-display Ignore requests to change the current **tty** or X window system's **DISPLAY** variable re‐ spectively. This is useful to lock the pinentry to pop up at the **tty** or display you started the agent. **--listen-backlog** _n_ Set the size of the queue for pending connections. The default is 64. **--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 con‐ nect 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 ma‐ chine. ### --enable-extended-key-format ### --disable-extended-key-format Since version 2.2.22 keys are created in the extended private key format by default. Changing the passphrase of a key will also convert the key to that new format. This key format is supported since GnuPG version 2.1.12 and thus there should be no need to disable it. Anyway, the disable option still allows to revert to the old behavior for new keys; be aware that keys are never migrated back to the old format. If the enable option has been used the disable option won't have an effect. The advantage of the extended private key format is that it is text based and can carry additional meta data. In extended key format the OCB mode is used for key protection. ### --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). Conse‐ quently, 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 fol‐ lowing 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 similar 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. **--auto-expand-secmem** _n_ 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 pre‐ fixes 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. **--s2k-calibration** _milliseconds_ 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 **gpgconf** **--reload** **gpg-agent**) and the S2K count is then re-calibrated. **--s2k-count** _n_ 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 op‐ eration 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 ## 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 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 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: [ad‐ dgnupghome]). ## SIGNALS A running **gpg-agent** may be controlled by signals, i.e. using the **kill** command to send a sig‐ nal 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**, **s2k-count**, **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)](https://www.chedong.com/phpMan.php/man/gpg/1/markdown), [**gpgsm**(1)](https://www.chedong.com/phpMan.php/man/gpgsm/1/markdown), [**gpgconf**(1)](https://www.chedong.com/phpMan.php/man/gpgconf/1/markdown), [**gpg-connect-agent**(1)](https://www.chedong.com/phpMan.php/man/gpg-connect-agent/1/markdown), [**scdaemon**(1)](https://www.chedong.com/phpMan.php/man/scdaemon/1/markdown) 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. GnuPG 2.2.27 2020-12-21 [GPG-AGENT(1)](https://www.chedong.com/phpMan.php/man/GPG-AGENT/1/markdown)