string uri = string.Format("https://api.box.com/2.0/files/{0}", fileId);
        string body = "{"shared_link": {"access": "open"}}";

        byte[] postArray = Encoding.ASCII.GetBytes(body);

        using (var client = new WebClient())
        {
            client.Headers.Add("Content-Type", "application/x-www-form-urlencoded");
            client.Headers.Add("Authorization: Bearer " + token);

            var response = client.UploadData(uri, postArray);

            var responseString = Encoding.Default.GetString(response);
        }

string uri = String.Format(UriFiles, fileId);
        string response = string.Empty;
        string body = "{"shared_link": {"access": "open"}}";
        byte[] postArray = Encoding.ASCII.GetBytes(body);

        try
        {
            using (var client = new WebClient())
            {
                client.Headers.Add("Authorization: Bearer " + token);
                client.Headers.Add("Content-Type", "application/json");
                response = client.UploadString(uri, "PUT", body);
            }
        }
        catch (Exception ex)
        {
            return null;
        }
        return response;