How do you connect to a HTTPS url?

App.js

(function() {
 
    var myView = Ti.UI.createView();
    var win = Ti.UI.createWindow();
    var label = Ti.UI.createLabel();
 
    myView.add(label);
    win.add(myView);
    win.open();
 
    var xhr = Ti.Network.createHTTPClient({
        onload : function() {
            Ti.API.info("Successfully received data from HTTPS");
            label.text = this.responseText;
        },
        onerror : function() {
            Ti.API.info("There was an error receiving data from HTTPS.");
        }
    });
    xhr.open("GET", "https://www.muthwill-it.se/other/titanium/1.txt");
    xhr.send();
 
})();

I've been searching for ages to an answer to this question that I'm sure many people have. Is there a simple guide to enable HTTPS in an HTTPClient? There's nothing wrong with the url either, here's the link: Muthwll-IT JSON Example - Using HTTPS

I've seen somewhere that you need to download and validate the certificate, but how on Earth do you do that?

Thank you very much for your help!