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public class JarRunner {
  public static void main(String[] args) throws IOException, 
    ClassNotFoundException,NoSuchMethodException, InvocationTargetException {
  
    URL url = new URL(args[0]);
    
    // Create the class loader for the application jar file
    JarClassLoader cl = new JarClassLoader(url);
    
    // Get the application's main class name
    String name = cl.getMainClassName();
    
    // Get arguments for the application
    String[] newArgs = new String[args.length - 1];
    System.arraycopy(args, 1, newArgs, 0, newArgs.length);
    
    // Invoke application's main class
    cl.invokeClass(name, newArgs);
  }
}

class JarClassLoader extends URLClassLoader {
  private URL url;
  public JarClassLoader(URL url) {
    super(new URL[] { url });
    this.url = url;
  }

  public String getMainClassName() throws IOException {
    URL u = new URL("jar", """jar", "", url + ""!/"");
    JarURLConnection uc = (JarURLConnection) u.openConnection();
    Attributes attr = uc.getMainAttributes();
    return attr != null ? attr.getValue(Attributes.Name.MAIN_CLASS) : null;
  }

  public void invokeClass(String name, String[] args)
      throws ClassNotFoundException, NoSuchMethodException,
      InvocationTargetException {
    Class c = loadClass(name);
    Method m = c.getMethod("main""main", new Class[] { args.getClass() });
    m.setAccessible(true);
    int mods = m.getModifiers();
    if (m.getReturnType() != void.class || !Modifier.isStatic(mods)
        || !Modifier.isPublic(mods)) { throw new NoSuchMethodException("main""main"); }
    try {
      m.invoke(null, new Object[] { args });
    } catch (IllegalAccessException e) { System.out.println(""Access denied""); }
  }
}

public void invokeClass(String name, String[] args)
    throws ClassNotFoundException, NoSuchMethodException, 
    InvocationTargetException, GeneralSecurityException, IOException {
  Class c = loadClass(name);
  Certificate[] certs = c.getProtectionDomain().getCodeSource().getCertificates();
  if(certs == null) {
    System.out.println(""No signature!""); return;  // return, do not execute if unsigned
  }  

  KeyStore ks = KeyStore.getInstance("JKS""JKS");
  ks.load(new FileInputStream(System.getProperty(""user.home""+ File.separator + ""keystore.jks"")),
    "loadkeystorepassword""loadkeystorepassword".toCharArray());
  Certificate pubCert = ks.getCertificate("user""user");  // user is the alias
  certs[0].verify(pubCert.getPublicKey()); // check with the trusted public key, else throws exception
}