Location based services are becoming increasingly important to the success and attractiveness of next generation wireless systems. Service providers will use location information to introduce new services and greatly enhance many existing services. Maintaining location privacy is an important requirement that must be met for these services to be widely deployed. It is a challenge to maintain location privacy while still providing the flexible access to location information required to enable a rich set of location based services. In this paper we define a high-level architecture for providing LBS and classify services according to several basic criteria. To support these services we propose a hierarchical key distribution method. Four methods are proposed to deliver hierarchical location information while maintaining privacy. We evaluate the efficiency of the system in terms of message delivery and key management overhead.