Wikidata/Berlin summit 2012/single sign-on

a problem that exists in all areas
hopes to find a solution during Hackathon
normally: login to one WP, be logged in to other languages as well
Wikidata: we want to authenticate to other services.
This doesn't work (e.g. upload of files to WP but not to commons).
SSO would be great!

Why is it harder than it seems?

oauth? nice, but not here. (why?)
privacy concerns: people believe to be editing in WP but then they realize they are in WD. Unclear how likely this is a problem.

Q. Ryan:why don't you use the existing CentralAuth system, already in place in all Wikimedia projects? A: not sure; maybe there were some assumptions made originally that aren't completely true ...

Q. To all: Who sees a problem with SSO? A. (by D.K.) [... missing part of discussion...] Tim: the reason why you can't upload to Commons from another Wikimedia wiki is it's not currently possible to log external actions

anonymous editing without display of IP address must be possible, people who enter politically sensitive data might accidentally be traceable because of SSO (?)