Repost: How to Sign a JAR File
When JAR files need to be downloaded as part of a Java applet or Webstart deployment it is best to digitally sign the JAR files.
Signing with a Test Certificate
1. Make sure that you have a Java SDK keytool and jarsigner in your path. These tools are located in the Java SDK bin directory.
2. Create a new key in a new keystore as follows:
keytool -genkey -keystore myKeystore -alias myself
You will be prompted for information regarding the new key, such as password, name, etc. This will create the myKeystore file on disk.
3. Then create a self-signed test certificate as follows:
keytool -selfcert -alias myself -keystore myKeystore
This will prompt you for a password. Generating the certificate may take a few minutes.
4. Check to make sure that everything is okay. To list the contents of the keystore, use this command:
keytool -list -keystore myKeystore
It should list something like:
Keystore type: jks
Keystore provider: SUN
Your keystore contains 1 entry:
myself, Tue Jan 23 19:29:32 PST 2001, keyEntry,
Certificate fingerprint (MD5):
5. Finally, sign the JAR file with the test certificate as follows:
jarsigner -keystore myKeystore test.jar myself
6. Repeat these steps for all your JAR files.
Note that a self-signed test certificate should only be used for internal testing, since it does not guarantee the identity of the user and therefore cannot be trusted. A trustworthy certificate can be obtained from a certificate authority, such as VeriSign orThawte, and should be used when the application is put into production
Make sure you add the following tag to your .jnlp file: