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 // Trusted.java

import java.security.*;

public class Trusted {

   // load native libraries
   static{
      System.loadLibrary("NativeMethodLib1");
	  System.loadLibrary("NativeMethodLib2");
	  ...
   }

   // private native methods
   private native void nativeOperation1(byte[] data, int offset, int len);
   private native void nativeOperation2(...)
   ...
 
   // wrapper methods perform 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();
      }

      nativeOperation1(data, offset, len);
   }
   
   public void doOperation2(...){
      ...
   }
}