HttpPost passing JSON data with authentication

See more:

Windows

C#3.5

console

Hi all,

I am trying to call a web service by passing JSON data. The web service accepts the authentication, where we need to pass the username and password to authenticate.
I am sorry guys, I couldn't disclose the URL and the Username.

Below is my method to do the job.

private static void MakeRequest(string url, string user_name)
       {
           try
           {
               var webAddr = url;
               var httpWebRequest = (HttpWebRequest)WebRequest.Create(webAddr);
               httpWebRequest.ContentType = "application/json;";
               httpWebRequest.Method = "POST";
               //password is blank
               var credentialBuffer = new UTF8Encoding().GetBytes(user_name + ":" + "");
               httpWebRequest.Headers["Authorization"] = "Basic " + Convert.ToBase64String(credentialBuffer);

               using (var streamWriter = new StreamWriter(httpWebRequest.GetRequestStream()))
               {
                   string json = "{\"x\":\"true\"}";

                   streamWriter.Write(json);
                   streamWriter.Flush();
               }

               var httpResponse = (HttpWebResponse)httpWebRequest.GetResponse();
               using (var streamReader = new StreamReader(httpResponse.GetResponseStream()))
               {
                   var result = streamReader.ReadToEnd();
               }
           }
           catch (Exception ex)
           {

               throw;
           }
}

When I call the method by passing URL and the username, it is returning error as "The remote server returned an error: (422) Unprocessable Entity."
I guess I am not using the proper authentication method.

Please help.