As groupwise have the ICAL reader "Subscribe" where we can place the vibe calendar link (ical). But it does not provide the authentication. What we need now if the ability to lock the calendar to authenticated users only. Not only who have the link can read it. If a company user leaves the company he still can read the calendars using a third party ical reader. If we have this lock simply when disabling his account he wont be able to read it any more