C# – Using a self-signed certificate with .NET’s HttpWebRequest/Response


I'm trying to connect to an API that uses a self-signed SSL certificate. I'm doing so using .NET's HttpWebRequest and HttpWebResponse objects. And I'm getting an exception that:

The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel.

I understand what this means. And I understand why .NET feels it should warn me and close the connection. But in this case, I'd like to just connect to the API anyway, man-in-the-middle attacks be damned.

So, how do I go about adding an exception for this self-signed certificate? Or is the approach to tell HttpWebRequest/Response not to validate the certificate at all? How would I do that?

Best Solution

Turns out, if you just want to disable certificate validation altogether, you can change the ServerCertificateValidationCallback on the ServicePointManager, like so:

ServicePointManager.ServerCertificateValidationCallback = delegate { return true; };

This will validate all certificates (including invalid, expired or self-signed ones).