Assuring Spatio-Temporal Integrity on Mobile Devices with Minimum Location Disclosure

Abstract

Since the boom of smartphones and location-based services, spatio-temporal data (i.e., user locations with timestamps) have become increasingly essential in many real-life applications. To ensure these data are faithfully extracted from the underlying location tracking hardware and not altered by any malicious party or the user himself/herself, integrity assurance schemes such as digital signatures or message authentication codes (MAC) must be adopted. However, these conventional schemes disclose to the verifier the complete plaintext location and thus jeopardize users' privacy. In this paper, we propose an integrity assurance scheme with minimum location disclosure. That is, the granule of the disclosed location is just small enough to prove the user is/has been to a certain place, and the verifier cannot learn anything beyond it. To this end, we propose a new MAC scheme called Prefix-verifiable MAC (PMAC), based on which we design indexes and protocols to authenticate both spatial and spatio-temporal predicates. Security analysis and experimental results show our scheme is both secure and efficient for practical use.

Location Proof Systems for Smart Internet of Things: Requirements, Taxonomy, and Comparative Analysis

“…Location Proof Systems Based on Symmetric Cryptographic Primitives: Haibu et al [59] proposed a spatiotemporal integrity scheme using a prefix-verifiable message authentication code to achieve unforgeable location evidence on mobile devices. The threat model of the scheme assumes the user and the verifier both are semi-trusted.…”

“…A promising feature of the scheme is support for spatiotemporal predicates. The method presented in [59] has a location authenticator module, which relies on the CPU security (e.g., ARM's TrustZone and Intel's trusted execution technology) to boot-load a trusted environment for providing enterprise-level security. Samsung KNOX is another example of providing a trusted environment in smart devices.…”