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

public class FileEncryptor {

  public static void main(String[] args) {

    if (args.length != 2) {
      System.err.println("Usage: java FileEncryptor filename password");
      return;
    }

    String filename = args[0];
    String password = args[1];

    if (password.length() < 8 ) {
      System.err.println("Password must be at least eight characters long");
    }
    
    try {
      FileInputStream fin = new FileInputStream(args[0]);
      FileOutputStream fout = new FileOutputStream(args[0] + ".des");

      // Create a key.
      byte[] desKeyData = password.getBytes();
      DESKeySpec desKeySpec = new DESKeySpec(desKeyData);
      SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
      SecretKey desKey = keyFactory.generateSecret(desKeySpec);

      // Use Data Encryption Standard.
      Cipher des = Cipher.getInstance("DES/CBC/PKCS5Padding");
      des.init(Cipher.ENCRYPT_MODE, desKey);
      
      // Write the initialization vector onto the output.
      byte[] iv = des.getIV();
      DataOutputStream dout = new DataOutputStream(fout);
      dout.writeInt(iv.length);
      dout.write(iv);
      
      byte[] input = new byte[64];
      while (true) {
        int bytesRead = fin.read(input);
        if (bytesRead == -1) break;
        byte[] output = des.update(input, 0, bytesRead);
        if (output != null) dout.write(output);
      }
      
      byte[] output = des.doFinal();
      if (output != null) dout.write(output);
      fin.close();
      dout.flush();
      dout.close();

    }
    catch (InvalidKeySpecException ex) {System.err.println(ex);}
    catch (InvalidKeyException ex) {System.err.println(ex);}
    catch (NoSuchAlgorithmException ex) {System.err.println(ex);}
    catch (NoSuchPaddingException ex) {System.err.println(ex);}
    catch (BadPaddingException ex) {System.err.println(ex);}
    catch (IllegalBlockSizeException ex) {System.err.println(ex);}
    catch (IOException ex) {System.err.println(ex);}
  }
}