Privacy Preserving in Range-Based Cooperative Indoor Localization

Cooperative localization offers a potential solution to the limitation of anchor-deployment in range-based localization system. However, there is a huge risk of location leakage in the cooperative process. Several privacy-preserving schemes have been proposed to address this problem. Unfortunately, the inter-anchor communication makes these schemes unable to provide strong privacy guarantees. To tackle this issue, a secure and lightweight scheme based on partially homomorphic encryption is presented in this letter. Specifically, the least-squares estimation algorithm is decomposed into a form matching the additive homomorphism, so that each participated anchor can individually perform the encryption of its respective location-related information without interacting with others. During the entire localization process, private information of all entities involved remains secret, which could motivate users who have just done the positioning to participate in the localization, acting as pseudo-anchors for cooperative localization to solve the problem of dense anchor deployment. Experimental results and theoretical analysis have shown the proposed scheme meets the desired properties for a more pervasive use of indoor localization.