trayToDB/trayToDB/Settings.cs

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

namespace trayToDB
{
    public partial class Settings : Form
    {
        static readonly string PasswordHash = "P@SsW0Rd";
        static readonly string SaltKey = "s!PmTe$teR";
        static readonly string VIKey = "@1B2c3D4e5F6g7H8";

        public Settings()
        {
            InitializeComponent();
        }

        public static string Decrypt(string encryptedText)
        {
            try
            {
                byte[] cipherTextBytes = Convert.FromBase64String(encryptedText);
                byte[] keyBytes = new Rfc2898DeriveBytes(PasswordHash, Encoding.ASCII.GetBytes(SaltKey)).GetBytes(256 / 8);
                var symmetricKey = new RijndaelManaged() { Mode = CipherMode.CBC, Padding = PaddingMode.None };

                var decryptor = symmetricKey.CreateDecryptor(keyBytes, Encoding.ASCII.GetBytes(VIKey));
                var memoryStream = new MemoryStream(cipherTextBytes);
                var cryptoStream = new CryptoStream(memoryStream, decryptor, CryptoStreamMode.Read);
                byte[] plainTextBytes = new byte[cipherTextBytes.Length];

                int decryptedByteCount = cryptoStream.Read(plainTextBytes, 0, plainTextBytes.Length);
                memoryStream.Close();
                cryptoStream.Close();
                return Encoding.UTF8.GetString(plainTextBytes, 0, decryptedByteCount).TrimEnd("\0".ToCharArray());
            }
            catch (System.FormatException)
            {
                return null;
            }
        }

        public static string Encrypt(string plainText)
        {
            byte[] plainTextBytes = Encoding.UTF8.GetBytes(plainText);

            byte[] keyBytes = new Rfc2898DeriveBytes(PasswordHash, Encoding.ASCII.GetBytes(SaltKey)).GetBytes(256 / 8);
            var symmetricKey = new RijndaelManaged() { Mode = CipherMode.CBC, Padding = PaddingMode.Zeros };
            var encryptor = symmetricKey.CreateEncryptor(keyBytes, Encoding.ASCII.GetBytes(VIKey));

            byte[] cipherTextBytes;

            using (var memoryStream = new MemoryStream())
            {
                using (var cryptoStream = new CryptoStream(memoryStream, encryptor, CryptoStreamMode.Write))
                {
                    cryptoStream.Write(plainTextBytes, 0, plainTextBytes.Length);
                    cryptoStream.FlushFinalBlock();
                    cipherTextBytes = memoryStream.ToArray();
                    cryptoStream.Close();
                }
                memoryStream.Close();
            }
            return Convert.ToBase64String(cipherTextBytes);
        }

        private void Settings_Load(object sender, EventArgs e)
        {
            serverSelector.Text = Properties.Settings.Default.server;
            port.Value = Properties.Settings.Default.port;
            userTextbox.Text = Properties.Settings.Default.user;
            passwordTextbox.Text = Decrypt(Properties.Settings.Default.password);
            databaseTextbox.Text = Properties.Settings.Default.database;
        }

        private void cancelButton_Click(object sender, EventArgs e)
        {
            this.Dispose();
        }

        private void okButton_Click(object sender, EventArgs e)
        {
            Properties.Settings.Default.server = serverSelector.Text;
            Properties.Settings.Default.port = (int)port.Value;
            Properties.Settings.Default.user = userTextbox.Text;
            Properties.Settings.Default.password = Encrypt(passwordTextbox.Text);
            Properties.Settings.Default.database = databaseTextbox.Text;
            Properties.Settings.Default.Save();

            this.Dispose();
        }

        private void testButton_Click(object sender, EventArgs e)
        {
            string connStr = "server=" + serverSelector.Text + "; user=" + userTextbox.Text + "; database=" + databaseTextbox.Text + "; port=" + (int)port.Value + "; password=" + passwordTextbox.Text;
            MySqlConnection conn = new MySqlConnection(connStr);
            try
            {
                conn.Open();
                MessageBox.Show("Successfully connected to the database!");
                conn.Close();
            }
            catch(MySqlException ex)
            {
                MessageBox.Show(ex.Message);
            }
        }
    }
}