import java.security.*;
import javax.crypto.*;
//
// encrypt and decrypt using the DES private key algorithm
public class PrivateExample {

  public static void main (String[] args) throws Exception {
    //
    // check args and get plaintext
    if (args.length !=1) {
      System.err.println("Usage: java PrivateExample text");
      System.exit(1);
    }
    byte[] plainText = args[0].getBytes("UTF8");
    //
    // get a DES private key
    System.out.println( "\nStart generating DES key" );
    KeyGenerator keyGen = KeyGenerator.getInstance("DES");
    keyGen.init(56);
    Key key = keyGen.generateKey();
    System.out.println( "Finish generating DES key" );
    //
    // get a DES cipher object and print the provider
    Cipher cipher = Cipher.getInstance("DES/ECB/PKCS5Padding");
    System.out.println( "\n" + cipher.getProvider().getInfo() );
    //
    // encrypt using the key and the plaintext
    System.out.println( "\nStart encryption" );
    cipher.init(Cipher.ENCRYPT_MODE, key);
    byte[] cipherText = cipher.doFinal(plainText);
    System.out.println( "Finish encryption: " );
    System.out.println( new String(cipherText, "UTF8") );

    //
    // decrypt the ciphertext using the same key
    System.out.println( "\nStart decryption" );
    cipher.init(Cipher.DECRYPT_MODE, key);
    byte[] newPlainText = cipher.doFinal(cipherText);
    System.out.println( "Finish decryption: " );

    System.out.println( new String(newPlainText, "UTF8") );
  }
}