Login / Registo MD5

LOGIN
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using MySql.Data.MySqlClient;
using System.Security.Cryptography;

namespace WindowsFormsApplication6
{
    public partial class Login : Form
    {
        public Login()
        {
            InitializeComponent();
        }

        private void linkLabel1_LinkClicked(object sender, LinkLabelLinkClickedEventArgs e)
        {
            Registro reg = new Registro();
            reg.Show();
            this.Hide();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            MD5 md5Hasher = MD5.Create();
            byte[] data = md5Hasher.ComputeHash(Encoding.Default.GetBytes(textBox2.Text));
            StringBuilder sBuilder = new StringBuilder();
            for (int i = 0; i < data.Length; i++)
            {
                sBuilder.Append(data[i].ToString("x2"));
            }
            string cs = "data source=localhost; database=login; user id=root; pwd=''";
            MySqlConnection liga = new MySqlConnection(cs);
            string query = "select * from login where user =?u and pass=?p";
            try
            {
                MySqlCommand cmd = new MySqlCommand(query, liga);
                cmd.Parameters.AddWithValue("?u", textBox1.Text);
                cmd.Parameters.AddWithValue("?p", sBuilder);
                liga.Open();
                MySqlDataReader leitor = cmd.ExecuteReader();
                if (leitor.Read())
                {
                    MainMenu mm = new MainMenu();
                    mm.Show();
                    this.Hide();
                }
                else MessageBox.Show(Convert.ToString(sBuilder));
            }
            catch (MySqlException ex)
            {
                MessageBox.Show(ex.Message);
            }

            finally
            {
                liga.Close();
            }
        }
    }
}

REGISTO

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using MySql.Data.MySqlClient;
using System.Security.Cryptography;

namespace WindowsFormsApplication6
{
    public partial class Registro : Form
    {
        public Registro()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            string cs = "data source=localhost; database=login; user id=root; pwd=''";
            MySqlConnection liga = new MySqlConnection(cs);
            string query = "insert into login(user, pass) values (?u, ?p)";
            DialogResult result = MessageBox.Show("Deseja inserir o registro?", "Registro", MessageBoxButtons.OKCancel, MessageBoxIcon.Question);
            try
            {
                MySqlCommand cmd = new MySqlCommand(query, liga);
                cmd.Parameters.AddWithValue("?u", textBox1.Text);
                MD5 md5Hasher = MD5.Create();
                byte[] data = md5Hasher.ComputeHash(Encoding.Default.GetBytes(textBox2.Text));
                StringBuilder sBuilder = new StringBuilder();
                for (int i = 0; i < data.Length; i++)
                {
                    sBuilder.Append(data[i].ToString("x2"));
                }
                cmd.Parameters.AddWithValue("?p", sBuilder);
                liga.Open();
                if(result == DialogResult.OK)
                {
                    cmd.ExecuteNonQuery();
                    Login login = new Login();
                    login.Show();
                    this.Close();

                }
            }

            catch (MySqlException ex)
            {
                MessageBox.Show(ex.Message);
            }

            finally
            {
                liga.Close();
            }
        }
    }
}