As you probably know it is possible to connect to Sharepoint sites and doclibs via WebDAV in Wnidows explorer view, by creating new network location or by mapping new network drive to Sharepoint site. If your site works via http WebDAV will use http, if site uses https – WebDAV also will work over https. What if you want to force users to use https instead of http?
First of all you have to configure your Sharepoint stie to use https (purchase SSL certificate, install it on your IIS server, add https binding to Sharepoint site in IIS manager, change alternate access mappings in Central administration). After that you need to redirect traffic from http to https. In order to do that use URL Rewrite IIS module and add new blank rule which looks like this:
This rule will redirect http requests to https in browser. But also it will redirect http to https for WebDAV clients. If you will open fiddler and will try to open network location which uses http url then you will see something like that (test was done on Windows 10 client):
HTTP/1.1 301 Moved Permanently
Where instead of example.com will be url of your Sharepoint site. I.e. URL Rewrite IIS module successfully redirects traffic also for WebDAV.