Just like AbleCommerce 7.x, AbleCommerce Gold uses a specific configuration file to identify which pages/folders should force SSL.  Obviously key pages like the login page, the admin pages, checkout etc are all set to force SSL by default.
But sometimes you need your own custom stuff to force SSL.  In my case, it’s my Quickbooks Connector for AbleCommerce.  The Intuit Web Connector program will only transfer to a public IP using HTTPS.  Any attempt to do so with straight HTTP will result in an Authentication Failed error response.
To force SSL connection on a specific page/file in your AbleCommerce Gold install, edit the /App_Data/ssl.config file and add the appropriate file name.  You’ll see the necessary syntax with the other entries in the file.
Make sure the file name is in all lower case in the ssl.config AND the actual file on your drive.    Able has had some issues with failing to recognize filenames when the case is not the same between what’s in the ssl.config and the actual file itself.  This was supposed to be corrected in Gold R3 however that has not been confirmed as of this writing.