如何解密在SQL数据库中加密的密码[C＃]

Question

所以我遇到了这个脚本的问题。我在我的项目中创建了一个新类，它名为AesCryp.cs，它带有加密和解密方法。这是脚本：

class AesCryp
{
    public static string IV = "xxxxxxxxxxxxxxxx";
    public static string Key = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx";

    public static string Encrypt(string decrypted)
    {
        byte[] textbytes = ASCIIEncoding.ASCII.GetBytes(decrypted);
        AesCryptoServiceProvider encdec = new AesCryptoServiceProvider();
        encdec.BlockSize = 128;
        encdec.KeySize = 256;
        encdec.Key = ASCIIEncoding.ASCII.GetBytes(Key);
        encdec.IV = ASCIIEncoding.ASCII.GetBytes(IV);
        encdec.Padding = PaddingMode.PKCS7;
        encdec.Mode = CipherMode.CBC;

        ICryptoTransform icrypt = encdec.CreateEncryptor(encdec.Key, encdec.IV);

        byte[] enc = icrypt.TransformFinalBlock(textbytes, 0, textbytes.Length);
        icrypt.Dispose();

        return Convert.ToBase64String(enc);
    }

    public static string Decrypt(string encrypted)
    {
        byte[] encbytes = Convert.FromBase64String(encrypted);
        AesCryptoServiceProvider encdec = new AesCryptoServiceProvider();
        encdec.BlockSize = 128;
        encdec.KeySize = 256;
        encdec.Key = ASCIIEncoding.ASCII.GetBytes(Key);
        encdec.IV = ASCIIEncoding.ASCII.GetBytes(IV);
        encdec.Padding = PaddingMode.PKCS7;
        encdec.Mode = CipherMode.CBC;

        ICryptoTransform icrypt = encdec.CreateDecryptor(encdec.Key, encdec.IV);

        byte[] dec = icrypt.TransformFinalBlock(encbytes, 0, encbytes.Length);
        icrypt.Dispose();

        return ASCIIEncoding.ASCII.GetString(dec);
    }
}

我在创建新帐户时已经创建了它，它将加密密码并将其插入数据库。这是注册脚本：

public bool Register(string user, string pass)
    {
        string query = $"INSERT INTO users (ID, Username, Password) VALUES ('', '{user}', '{pass}');";

        try
        {
            if (OpenConnection())
            {
                MySqlCommand cmd = new MySqlCommand(query, db);

                try
                {
                    cmd.ExecuteNonQuery();
                    return true;
                }
                catch (Exception ex)
                {
                    return false;
                }
            }
            else
            {
                db.Close();
                return false;
            }
        }
        catch (Exception ex)
        {
            db.Close();
            return false;
        }
    }

这是SignUp按钮脚本：

private void SignUp_Click(object sender, EventArgs e)
    {
        string user = usernameTxt.Text;
        string pass = AesCryp.Encrypt(passwordTxt.Text);

        if(Register(user, pass))
        {
            MessageBox.Show($"User {user} has been created!");
        }
        else
        {
            MessageBox.Show($"User {user} has not been created!");
        }

    }

然而，我真的很困惑我将如何制作它，以便在我尝试登录时解密数据库中的加密密码。这是我的登录脚本，没有任何解密（因为我不完全确定我会怎么做）

public bool IsLogin(string user, string pass)
    {
        string query = $"SELECT * FROM users WHERE Username='{user}' AND Password='{pass}';";

        try
        {
            if (OpenConnection())
            {
                MySqlCommand cmd = new MySqlCommand(query, conn);
                MySqlDataReader reader = cmd.ExecuteReader();

                if (reader.Read())
                {
                    reader.Close();
                    conn.Close();
                    return true;
                }
                else
                {
                    reader.Close();
                    conn.Close();
                    return false;
                }
            }
            else
            {
                conn.Close();
                return false;
            }
        }
        catch (Exception ex)
        {
            conn.Close();
            return false;
        }
    }

这是登录按钮脚本：

private void Login_Click(object sender, EventArgs e)
    {
        string user = usernameTxt.Text;
        string pass = passwordTxt.Text;

        if (IsLogin(user, pass))
        {
            MessageBox.Show($"Welcome {user}!");
        }
        else
        {
            MessageBox.Show("Username or password is incorrect!");
        }
    }

如果有人能帮助我，那就太棒了。谢谢！