Curl avec authentification de l'utilisateur en C #

Je veux faire la demande de courbure suivante en C #:

string url = "http://localhost:8080/geoserver/rest/workspaces";
WebRequest request = WebRequest.Create(url);

request.ContentType = "Content-type: text/xml";
request.Method = "POST";
string authInfo = "admin:geoserver";
request.Headers["Authorization"] = "Basic " + authInfo;

byte[] buffer = Encoding.GetEncoding("UTF-8").GetBytes("<workspace><name>my_workspace</name></workspace>");
Stream reqstr = request.GetRequestStream();
reqstr.Write(buffer, 0, buffer.Length);
reqstr.Close();

WebResponse response = request.GetResponse();
...