Proximity-Based Positioning Scheme with Multi-layer Privacy.

This article investigates the use of proximity-based positioning as a simple, yet effective, positioning system in crowded areas. Particularly, proximity-based positioning is a range-free solution where a receiver computes its position by knowing where nearby receivers are. The main requirement, therefore, is that collaborative receivers need to share their position, which poses a privacy concern and potential limitation in the widespread use of such approach. This article proposes a scheme whereby encrypted positions are shared among the collaborative agents in order to implement a proximity-based solution that does not reveal the position of neighboring nodes. With the use of the homomorphic encryption, we establish a framework that will perform the required operations to obtain position estimates, while the information of any participating user or device will remain private. The concept is investigated and then experimental results provided to support the proposed methodology, showing equivalent performance to the case where no privacy-security guarantees are provided.