public string base64Encode(string data)
{
    try
    {
        byte[] bt = new byte[data.Length];
        bt = System.Text.Encoding.UTF8.GetBytes(data);    
        string encodedData = Convert.ToBase64String(bt);
        return encodedData;
    }
    catch(Exception e)
    {
        throw new Exception("Some Error occured:-" + e.Message);
    }
}