CrossLink: Breaking Location Privacy by Linking Device Identifiers Across Protocols
Researchers present CrossLink, a passive tracing algorithm linking temporary device identifiers across LTE, WiFi, and BLE, reconstructing full traces for 83% of simulated users.
Smartphones emit temporary identifiers simultaneously over LTE, WiFi, and BLE, and per-protocol randomization defenses implicitly assume their protections compose across protocols. CrossLink is an uncertainty-aware tracing algorithm that stitches device identifiers across time, space, and protocols even when the adversary is fully passive and rotations are unsynchronized. In large-scale mobility simulation it reconstructs full traces for 83% of users versus 22% for the best single-protocol baseline. It remains effective under partial sniffer coverage, including strategically placed sniffers near LTE handover regions, mobile sniffers, and limited high-coverage subregions.