WebClient + HTTPS Issues

Question

I am currently integrating with a system created by a 3rd party. This system requires me to send a request using XML/HTTPS. The 3rd party send me the certificate and I installed it

I use the following code:

using (WebClient client = new WebClient())
{
   client.Headers.Add(HttpRequestHeader.ContentType, "text/xml");

   System.Text.ASCIIEncoding  encoding=new System.Text.ASCIIEncoding();
   var response = client.UploadData(address, "POST", encoding.GetBytes(msg));
}

This code returns the following WebException: The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel.

UPDATE Because it's a test server I am working against, the certificate isn't trusted and validation fails... To bypass this in test/debug enviroment, create a new ServerCertificateValidationCallback

ServicePointManager.ServerCertificateValidationCallback += new System.Net.Security.RemoteCertificateValidationCallback(bypassAllCertificateStuff);

and here is my "fake" callback

private static bool bypassAllCertificateStuff(object sender, X509Certificate cert, X509Chain chain, System.Net.Security.SslPolicyErrors error)
{
   return true;
}

Read more here and here

Answer 1

Go here.

Answer 2

For the VB.NET version of the original answer, here you go (converters don't work well when needing to wire up events with the 'AddressOf' operator). 1st code that goes before using a WebClient() or HttpWebRequest() object:

ServicePointManager.ServerCertificateValidationCallback = New System.Net.Security.RemoteCertificateValidationCallback(AddressOf bypassAllCertificateStuff)

..and the wired up method code:

Private Shared Function bypassAllCertificateStuff(ByVal sender As Object, ByVal cert As X509Certificate, ByVal chain As X509Chain, ByVal [error] As System.Net.Security.SslPolicyErrors) As Boolean
    Return True
End Function