  When using Online Social Networks, users often share information with
different social groups. When considering the backgrounds of the groups there
is often no or little intersection within the members. This means that a user
who shares information often has to share it with all members of all groups. It
can be problematic that the user cannot decide which group sees which
information. Our approach therefore, allows users to decide for every bit of
information who can access it. Further, protected circles can be created, where
users can share information within. Shared information and circles are
encrypted and the keys can be distributed by proxies.
