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// Trusted.java

import java.security.*;

public class Trusted {

   public static void loadLibrary(final String library){
      AccessController.doPrivileged(new PrivilegedAction<Void>() {
         public Void run() {
             System.loadLibrary(library);
             return null;
         }
      });
   }
}

---------------------------------------------------------------------------------

// Untrusted.java

public class Untrusted {

   private native void myMethod();

   public static void main(String[] args) {
      String library = new String("Library1NativeMethodLib");
      Trusted.loadLibrary(library);
      new Untrusted.nativeOperation();  // invoke the native method
   }
}

 // Trusted.java

import java.security.*;

public class Trusted {

   static{
      System.loadLibrary("Library1NativeMethodLib1");
	  System.loadLibrary("Library2NativeMethodLib2");
	  ...
   }

   // private native methods
   private native void nativeOperation1(byte[] data, int offset, int len);
   private native void nativeOperation2(...)
   ...
 
   // wrapper method performs SecurityManager and input validation checks
   public void doOperation1(byte[] data, int offset, int len) {
      // permission needed to invoke native method
      securityManagerCheck();

      if (data == null) {
         throw new NullPointerException();
      }

      // copy mutable input
      data = data.clone();

      // validate input
      if ((offset < 0) || (len < 0) || (offset > (data.length - len))) {
         throw new IllegalArgumentException();
      }

      nativeOperation(data, offset, len);
   }
}