Do as the Romans Do: Location Imitation-Based Edge Task Offloading for Privacy Protection

In edge computing, a user prefers offloading his/her task to nearby edge servers to maximize the offloading utility. However, this inevitably exposes the user's location privacy information when suffering from the side-channel attacks based on offloading decision behaviors and Received Signal Strength Indicators (RSSI). Existing works only consider the scenario with one untrusted edge server or defend only against one of the attacks. In this paper, we first study the edge task offloading problem with comprehensive privacy protection against these side-channel attacks from multiple edge servers. To address this problem while ensuring satisfactory offloading utility, we develop a <underline xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</u>ocation <underline xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</u>mitation-based Edge <underline xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</u>ask <underline xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">O</u>ffloading approach <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LITO</i>. Specifically, we first determine a suitable perturbation region centered at the user's real location for a balance between offloading utility and privacy protection, and then propose a modified Laplace mechanism to generate a fake location meeting geo-indistinguishability within the region. Subsequently, to mislead the side-channel attacks to the fake location, we design an approximate algorithm and a transmit power control strategy to imitate the offloading decisions and RSSIs at the fake location, respectively. Theoretical analysis and experimental evaluations demonstrate the performance of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LITO</i> in improving privacy protection and guaranteeing offloading utility.