Sorry for the delay in my answer, some business to attend to.
Yes I kind of forgot to mention that. I’ll add a note to the README.
As a matter of fact, this part is not covered very well. I’ll put some examples, in the meanwhile you can simply configure a reverse proxy via a HTTP server (e.g. nginx) and point some URL to the httpupload port (8828).
Do not expose 8828 directly, use the reverse proxy so you can map a “weird” unencrypted URL (http://hostname:8828) to a sane encrypted URL with a proper path (https://hostname/media).
That’s how is configured on Kontalk production server by the way. Using HTTPS on the default port also helps you with corporate-proxied connections (actually the problem is bigger here because the chat server itself runs on port 5222 so not really “proxyable”; we’ll address that as well in future releases).
Remember that the URL you configure in nginx (or whatever you’ll decide to use) must be configured in local.properties:
# HTTP URLs
HTTPUPLOAD_PUT_URL=https://prime.kontalk.net/media
HTTPUPLOAD_GET_URL=https://prime.kontalk.net/media
Also remember to use the same SSL certificate in nginx from the chat server configuration.