import java.io.*;
import javax.crypto.*;
import javax.crypto.spec.*;



public class DesLib {
   private DesLib() {}

   public static final int ver = 1;

   public static byte[] genKey() {
      byte[] bytes = null;
      try {
         KeyGenerator keyGen = KeyGenerator.getInstance("DES");
         SecretKey key = keyGen.generateKey();
         bytes = key.getEncoded(); // get the bytes of the key
      } catch (Exception e) {
         System.err.println(e); }
      return bytes;
   }


   public static SecretKey makeKey(byte[] key) {
      return new SecretKeySpec(key, "DES");
   }


   public static SealedObject encrypt(SecretKey sk, Serializable s) {
      SealedObject so = null;
      try {
         // Prepare the encrypter
         Cipher enc = Cipher.getInstance("DES");
         enc.init(Cipher.ENCRYPT_MODE, sk);
         // Seal (encrypt) the object
         so = new SealedObject(s, enc);
      } catch (Exception e) {
         System.err.println(e); }
      return so;
   }


   public static Object decrypt(SecretKey sk, SealedObject so) {
      Object o = null;
      try {
         // Get the algorithm used to seal the object
         String algoName = so.getAlgorithm(); // DES
         // Prepare the decrypter
         Cipher dec = Cipher.getInstance("DES");
         dec.init(Cipher.DECRYPT_MODE, sk);
         // Unseal (decrypt) the class
         o = so.getObject(dec);
      } catch (Exception e) {
         System.err.println(e); }
      return o;
   }
}