Download file over HTTPS using .NET (dotnet)

Question

I would like to download a file using VB.NET (preferably) or C# via HTTPS.

I have this code to download a file over plain HTTP:

Dim client As WebClient = New WebClient()
Dim wp As WebProxy = New WebProxy("[IP number of our proxy server]", [port number of our proxy server])
wp.Credentials = CredentialCache.DefaultCredentials
client.Proxy = wp
client.DownloadFile("http://sstatic.net/so/img/logo.png", "c:\logo.png")

This works.

How do I change this code to download a file that is stored on an HTTPS-server? I guess it has something to do with adding credentials or something.

Answer 1

You need to add a certificate validator:

// You need to call it only once in a static constructor or multiple times there is no problem
ServicePointManager.ServerCertificateValidationCallback = ValidateCertificate;

    private static bool ValidateCertificate(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)
    {
        return true;
    }

In VB:

ServicePointManager.ServerCertificateValidationCallback = AddressOf ValidateCertificate
Dim client As WebClient = New WebClient()
'...
'Your code

  Private Shared Function ValidateCertificate(sender As Object, certificate As X509Certificate, chain As X509Chain, sslPolicyErrors As SslPolicyErrors) As Boolean
        return True
  End Function