Steps for signing an executable jar file


1)	Create a new key in a new keystore as follows: 
keytool -genkey -keystore myKeystore -alias myself 
You will get prompted for a information about the new key, such as password, name, etc. This will create the myKeystore file on disk. 
2)	Then, create a self-signed test certificate as follows: 
keytool -selfcert -alias myself -keystore myKeystore 
This will prompt for the password. Generating the certificate takes a few minutes. 
3)	Check to make sure that everything is ok. To list the contents of the keystore, use the 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):
C2:E9:BF:F9:D3:DF:4C:8F:3C:5F:22:9E:AF:0B:42:9D
4)	Finally, sign the JAR file with the test certificate as follows: 
jarsigner -keystore myKeystore test.jar myself 


5)) exporting the certificate to a file
keytool -export -keystore myKeysotre –alias myself -file gc.cer