private void button1_Click(object sender, EventArgs e)
 {
     if (CheckTextBox())
     {
         var entryStr = txtEncrypt.Text;
         try
         {
             txtDecrypt.Text = BASE64.Encrypt(entryStr);
         }
         catch (Exception ex)
         {
             txtDecrypt.Text = ex.Message;
         }
     }
 }
        private void btnDecrypt_Click(object sender, EventArgs e)
        {
            if (CheckTextBox())
            {
                var    entryStr = txtEncrypt.Text;
                string result   = string.Empty;

                try
                {
                    txtDecrypt.Text = BASE64.Decrypt(entryStr);
                }
                catch (Exception ex)
                {
                    txtDecrypt.Text = ex.Message;
                }
            }
        }