Is It Privacy or Is It Access Control?

With the widespread use of online systems, there is an increasing focus on maintaining the privacy of individuals and information about them. This is often referred to as a need for privacy protection. The author briefly examines definitions of privacy in this context, roughly delineating between keeping facts private and statistical privacy that deals with what can be inferred from data sets. Many of the mechanisms used to implement what is commonly thought of as access control are the same ones used to protect privacy. This chapter explores when this is not the case and, in general, the interplay between privacy and access control on the one hand and, on the other hand, the separation of these models from mechanisms for their implementation.