TZ/lang preferences do not require consent, a CSRF token for a logged in user seems to me to be legitimate interest too, but I suppose you could see it as an identifier that can be linked back to the user. I still think if you're using it just for security purposes it counts, but the fact that the same identifier could be used for tracking based on differences on the backend is one of the reasons why this isn't just based on browser cookie settings.

well it's legal to create a hash and save it inside a database to count unique users. if the hash is not connected to any info that would identify a user (btw. user agent is some kind of identifing stuff) it is fine.

what I wanted to say is that cookies are not illegal by gdpr means and gdpr does not make a lot of stuff illegal, it's just that SAVING personal information or information that could identify somebody needs explicit permission.

edit: another thing ip addresses, by german law you are required to save it, when a user can register on your site and your site allows users to submit data. because authorities force you to give them out when a user did something illegal. (§ 7 Abs.1 Satz1 Nr.4 TKÜV, https://www.gesetze-im-internet.de/tk_v_2005/__7.html) In germany it's basically: fuck the privacy if they harmed our law! or at least you need a way to "activate" saving ip addresses.

How do you create the hash? If it's based on something that you can derive from the user (let's say sha1(IP address + User Agent), that seems pretty clearly identifying. If you generate a random identifier but save that identifier in their cookies and send it back next time, also pretty clearly identifying.

> How do you create the hash? If it's based on something that you can derive from the user (let's say sha1(IP address + User Agent), that seems pretty clearly identifying.

of course that is forbidden. and that's exactly why it is really hard to tell if companies honor it.