package untitled1;
import
import
import javax.crypto.CipherInputStream;
import
import
import javax.crypto.CipherOutputStream;
import *;
public class CipherLiu {
  public static void main(String[] args) {
    File f = new File("d:\\User.db");  
    InputStream is = null;
    try {
      is = new FileInputStream(f);
    }
    catch (FileNotFoundException ex) {
    }
   CipherInputStream cis = new CipherInputStream(is);  
  }
}

报错：CipherInputStream()has protected acess in javax.crypto.CipherInputStream
怎么解决？

我想问一下
CipherInputStream流怎么用？以及它的作用（功能）？