I'm just going to take a moment to appreciate the cognitive dissonance between "A batch on an unknown PC should log in..." and "I don't want to open insecure connections".
Okay, so. Notwithstanding that: You do specify in the question that it's a web server. So on the web server put the file into a location accessible via HTTP(S). Then, on this unknown PC, you can:
$ wget https://hostname.example.com/path/to/some/snazzy_file
$ curl -o snazzy_file --silent https://hostname.exameple.com/path/to/some/snazzy_file
If you don't want anyone else to get the file, you can, since it's a web server, use a set of
.htpasswd files (presuming Apache) or other means to lock down access to that file to either a range of client hosts or to a clients which provide authentication. If you decide to use HTTP Basic Auth, the URLs used for
wget would then be adjusted to: