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JSign runs on the Java platform, so you must correctly configure the JAVA_HOME environment variable to locate the installed JDK (Java Development Kit) on your system. This also makes the java and keytool commands this guide uses available on your PATH. This section shows how to set the JAVA_HOME environment variable and update the system PATH variable on both Linux and Windows.
This integration works with either Oracle Java or OpenJDK. Use JDK version 11, 17, or 21.
Many Linux distributions put java and keytool on the PATH when you install a JDK from the package manager, and the commands in this guide then work with JAVA_HOME unset. Run java -version and keytool -help first. If both commands run, skip this section.
Choose one of the following operating systems and perform the instructions:

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Linux

Perform the following steps to configure the JAVA_HOME variable in Linux:
1
Determine the installation path of JavaFind the path for the Java installation, such as /usr/lib/jvm/. Use the following command to list the installed JDKs:
Shell
For example, if you installed Java 21, the path is likely: /usr/lib/jvm/java-21-openjdk-amd64.
2
Edit the profile fileOpen a terminal and use a text editor to edit the /etc/profile file, which the system uses when users log in. You might need superuser privileges to edit this file.
Shell
3
Add the JAVA_HOME environment variable and update PATHAdd the following lines to the end of the /etc/profile file, replacing the path with the actual path to your Java installation:
None
4
Apply the changesAfter saving the file, apply the changes by sourcing the profile file:
Shell
5
Verify the configurationTo ensure that the JAVA_HOME variable is set correctly and the PATH is updated, you can check their values with the following commands:
Shell
You should see the path you set for JAVA_HOME and ensure $JAVA_HOME/bin is part of the PATH.

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Windows

Perform the following steps to configure the JAVA_HOME variable in Windows:
1
Determine the installation path of JavaEnsure Java is installed on your system. Note the installation path, typically something like C:\Program Files\Java\jdk-21.
2
Open System PropertiesSelect the Win + Pause/Break keys to open the System Properties window, or right-click This PC(or My Computer) and select Properties.Select Advanced system settings on the left sidebar.
3
Open Environment VariablesIn the System Properties window, select [ Environment Variables ] near the bottom of the window.
4
Create a new system variableIn the Environment Variables window, in the System variables section, select [ New ].In the New System Variable dialog box, enter the following:
  • Variable name: JAVA_HOME
  • Variable value: The path to your JDK installation (such as C:\Program Files\Java\jdk-21)
5
Update the PATH variableIn the System variables section, find and select the Path variable, then select [ Edit ].In the Edit Environment Variable dialog, select [ New ] and add %JAVA_HOME%\bin to the list. This enables the system to find the Java executables.
6
Create an additional system variable
  • Variable name: FXPKCS11_CFG
  • Variable value: The path to your FXPKCS11 configuration file (such as C:\Program Files\Futurex\fxpkcs11\fxpkcs11.cfg)
FXPKCS11_CFG points at the Futurex library configuration file (fxpkcs11.cfg), not at the SunPKCS11 provider configuration file (pkcs11.cfg) you create in the next section. If you left fxpkcs11.cfg in its default location of C:\Program Files\Futurex\fxpkcs11, this variable is optional.
7
Apply changesSelect [ OK ] on each dialog box to apply the changes and exit the dialog boxes.
8
Verify the configurationOpen a new Command Prompt window (select the Win + R keys, enter cmd, and press the Enter key).
  • Enter echo %JAVA_HOME%. You should see the path to your JDK installation.
  • Enter java -version to confirm that the system recognizes the Java installation.