I don’t think it’s a good idea to have to completely share an RSS or iCal stream of a board.
Imagine a Kanboard on the Internet… anyone can open this (ok, the link is somehow cryptic)
Can’t one at least set a webserver authtentification? One for the whole iCal / RSS part of a Kanboard instance (and only for that part)?
That would then be the data you normally have to enter as login data when setting up an iCal calendar with credentials.
As I said: one “login” to iCal/RSS for all boards (which are then still to be marked as public) would be enough.
The corresponding directories would then be protected by the web server (.htaccess). If that works: where would I have to put the htaccess file?
I hope i could make clear what i’am aiming for… 
Cheers, Fx