As an open standard for the short-range radio frequency communications, Bluetooth is suitable for Mobile Crowdsensing Systems (MCS). However, the massive deployment of personal Bluetooth-enabled devices also raises privacy concerns on their wielders. Hence, we investigate the privacy of the unilateral authentication protocol according to the recent Bluetooth standard v5.2. The contributions of the paper are twofold. (1) We demonstrate that the unilateral authentication protocol suffers from privacy weakness. That is, the attacker is able to identify the target Bluetooth-enabled device once he observed the device’s previous transmitted messages during the protocol run. More importantly, we analyze the privacy threat of the Bluetooth MCS, when the attacker exploits the proposed privacy weakness under the typical Internet of Things (IoT) scenarios. (2) An improved unilateral authentication protocol is therefore devised to repair the weakness. Under our formal privacy model, the improved protocol provably solves the traceability problem of the original protocol in the Bluetooth standard. Additionally, the improved protocol can be easily adapted to the Bluetooth standards because it merely employs the basic cryptographic components available in the standard specifications. In addition, we also suggest and evaluate two countermeasures, which do not need to modify the original protocol.
A Privacy Model for Social Networks