Firewall problem when encrypting/decryting a file

Question

Hi,
I'm a little bit new to cryptography.
When I encrypt a file using the javax.crypto classes, my firewall pops up and says "java.exe is attempting to connect to a DNS Server".
If I block the firewall, nothing else happens and the file gets encrypted as well. But I don't want to insecure all my customers having this firewall alerts.
Can anyone help me to stop that ? Thanks in advance,
- fridi -
This is the example code I am using:
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.security.GeneralSecurityException;
import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESedeKeySpec;
public class TestCrypt {
     public static void main(String[] args) throws Exception, GeneralSecurityException {
          String inFilename = args[0];
          String outFilename = args[1];
          byte[] keyArray = "My one and only key blablabalbal".getBytes();
          DESedeKeySpec desedeKeySpec = new DESedeKeySpec(keyArray);
          SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DESede");
          SecretKey key = keyFactory.generateSecret(desedeKeySpec);
          Cipher cip = Cipher.getInstance("DESede");
          cip.init(Cipher.ENCRYPT_MODE, key);
          FileInputStream fis = new FileInputStream(inFilename);
          CipherInputStream cis = new CipherInputStream(fis, cip);
          FileOutputStream fos = new FileOutputStream(outFilename);
          byte[] b = new byte[1024];
          int i = cis.read(b);
          while (i != -1) {
               fos.write(b, 0, i);
               i = cis.read(b);
          fos.close();
          cis.close();          
}

Answer 1

What version of Windows are you using, and what kind of security-related software are you running on the PC? Have you tried executing your code on a Linux/UNIX machine? It is highly unlikely that you'll see the problem on that platform - but if you do, there are tools where you can trace the execution of the JVM and filter it for name-service API calls to see where it is being initiated from.
I would still bet that some software on your PC is causing the outbound call.