In partially-trusted system environments like the WWW, the management of private user positions is a great challenge. On the one hand, location-based services of different partially-trusted providers have to be provided with position information. On the other hand, location servers, which are responsible for the management of user positions, might as well be operated by only partially-trusted providers. Therefore, in order to protect his privacy, a user might only want to store position information of limited precision on location servers, and also provide location-based services with position information of limited precision.

In this position paper, we sketch a novel position sharing approach that enables the user to tightly control the precision of position information stored on servers and provided to location-based services. This approach is based on the idea of distributing position information among a set of servers of different providers such that a compromised server only reveals information of strictly limited precision.