Ical with password and username

I want to create an iCal Calendar (I guess ical4j is a good lib for it?). I want to save this ical - File on my webserver.

After that the ical calendar is available over the internet. Now I want to sync this calendar to my phone (e.g.iPhone). But I want to have an authentification for this iCal calendar.

Is this possible? How can I do this?

Best Regards