Blu-ray players and PowerDVD require your Java Xlet (.jar) to be properly signed.

VLC does not check the signature, which is why your game worked there but not on real players. This guide uses ready-made certificate files so you don’t have to fight with old Java tools.

What you need

1. Your unsigned JAR (example: 00000.jar )
2. Five files (download them from this repo): https://github.com/aefirestone/easy-bdj-signing
• sig.ks → the keystore used for signing
• app.discroot.crt → the root certificate that must go on the disc
• The BD-J security tools (security.jar, bcprov-jdk15-137.jar, jdktools.jar)
3. Any Java 8 JDK (even a modern one is fine for signing)

Step 1 – Prepare a clean folder

Create a folder, for example:  C:\BDJ-Sign  

Two files (download them from this repo):

• Your unsigned JAR ( 00000.jar )
• sig.ks 
• app.discroot.crt 
• The BD-J security tools (security.jar, bcprov-jdk15-137.jar, jdktools.jar)

Step 2 – Sign the JAR

Open Command Prompt and run these commands one by one:

cd C:\BDJ-Sign

set TOOLS=C:\BDJ-Sign
set JAVA_HOME=C:\Path\To\Your\Java8\JDK
set CP=%TOOLS%\security.jar;%TOOLS%\bcprov-jdk15-137.jar;%TOOLS%\jdktools.jar

"%JAVA_HOME%\bin\java" -cp "%CP%" net.java.bd.tools.security.BDSigner -keystore sig.ks 00000.jar

Notes: 

• Replace C:\Path\To\Your\Java8\JDK with the real path to your JDK.
• If it asks for a password, just press Enter (this public keystore usually has an empty password).

When it finishes you should see lines like:

    updating: META-INF/MANIFEST.MF    
    adding: META-INF/SIG-BD00.SF    
    adding: META-INF/SIG-BD00.RSA    
    signing: ...    

 Your 00000.jar is now signed!

Step 3 – Put the certificate and JAR on the disc

Copy app.discroot.crt into both of these locations on your Blu-ray structure:

 BDMV/CERTIFICATE/app.discroot.crt 

 BDMV/CERTIFICATE/BACKUP/app.discroot.crt 

And finally put the signed JAR here:

 BDMV/JAR/00000.jar 

Step 4 – Build and test

Rebuild your ISO / disc image and test it on:

• PowerDVD
• A real Blu-ray player via BD-RE

It should now start correctly.

Quick Checklist

• JAR signed with BDSigner + sig.ks

• app.discroot.crt present in both CERTIFICATE and CERTIFICATE/BACKUP

• Signed JAR placed in BDMV/JAR/

Authors: Æ Firestone - Last Updated: 10/19/2026