1. A computer-implemented method of controlling privacy loss in a data sharing social network, the method comprising the steps of: providing the data sharing social network containing a plurality of user data objects for sharing the plurality of user data objects with a plurality of users according to an access control policy; dividing, by the computer, time into a sequence of time subintervals; and updating, by the computer, the access control policy at each time subinterval by randomly resetting some of the plurality of user data objects as public or private.