First-party isolation (privacy.firstparty.isolate
in about:config, set to false
by default) originated from the Tor browser and was recently added to Firefox. Unfortunately I haven't found enough official documentation and don't fully understand the functionality. Does this setting fully separate first-party cookies (third-party cookies can generally be safely disabled in web browsers, but additionally, how are they handled?) and related identifiable data (what data?).
1 Answer
From a cursory look, they isolate the cookies (and other data) on silos based on the domain you navigated to. So eg. a load to facebook.com when visiting www.stackexchange.com, would put facebook cookies inside a different silo than the facebook load when accessing twitter.com (however, the facebook loaded from meta.stackexchange.com would use the same silo as www.stackexchange.com)
Does this setting fully separate first-party cookies (third-party cookies can generally be safely disabled, but additionally, how are they handled?)
This is not "separating first-party cookies", as much as making a more detailed origin based on where you initially navigated to.
and related identifiable data (what data?).
cookies are just a part of the data a page could save. I'm pretty sure this would also apply to localStorage, maybe even partition the cache.