vigenere_cipher

//package vigenere;

import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;

public class Vigenere {
    static String alp = "abcdefghijklmnopqrstuvwxyz";
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        JFrame frame = new JFrame("Vigenere");
        frame.setLayout(new GridLayout(5, 2));
        frame.setSize(500, 150);
        JTextField plaintext = new JTextField();
        JTextField key = new JTextField();
        JLabel plaintxt = new JLabel("Plaintext");
        JLabel ky = new JLabel("key");
        JLabel encrypted = new JLabel("Encrypted");
        JLabel decrypted = new JLabel("Decrypted");
        JButton encrypt = new JButton("Encrypt");
        JButton decrypt = new JButton("Decrypt");
        frame.add(plaintxt);
        frame.add(plaintext);
        frame.add(ky);
        frame.add(key);
        frame.add(encrypt);
        frame.add(encrypted);
        frame.add(decrypt);
        frame.add(decrypted);
        frame.setVisible(true);
        encrypt.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent arg0) {
                // TODO Auto-generated method stub
                int k, p;
                char m;
                String enc="";
                if(key.getText().length() < plaintext.getText().length()) {
                    key.setText(key.getText()+key.getText());
                }
                for(int i = 0; i < plaintext.getText().length(); ++i) {
                    k = alp.indexOf(key.getText().charAt(i));
                    p = alp.indexOf(plaintext.getText().charAt(i));
                    m = alp.charAt((k+p)%26);
                    enc += m;
                }
                encrypted.setText(enc);
            }
        });
        decrypt.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent arg0) {
                // TODO Auto-generated method stub
                String dec = "";
                int k, p, tmp;
                char m;
                for(int i = 0; i < encrypted.getText().length(); ++i) {
                    k = alp.indexOf(key.getText().charAt(i));
                    p = alp.indexOf(encrypted.getText().charAt(i));
                    tmp = p - k;
                    if (tmp < 0) tmp += 26;
                    m = alp.charAt(tmp);
                    dec += m;
                }
                decrypted.setText(dec);
            }
        });
    }
}