Location privacy in wireless LAN

Abstract

Current Wireless LAN(WLAN) specification require all stations to use globally unique fixed MAC addresses. The MAC address is visible in all WLAN packets. Globally unique and fixed addresses enable an observer to collect history and profile data of wireless users. This cause a serious location privacy breach especially in public access networks. Several protection methods based on temporal address and periodical address updates have already been proposed. In this paper, we identify a new wireless location privacy attack-correlation attack-in the context of wireless LAN and high accuracy localization technique. Correlation attack is a method of utilizing the temporal and spatial correlation between the old and new pseudonym of nodes. we identified that solutions based on periodical address update cannot protect users from advanced tracking methods including correlation attack under such context. To combat such attacks, we propose the concept of a silent period. A silent period is defined as a transition period between the use of new and old pseudonyms, when a node is not allowed to disclose either the old or the new address. This makes it more difficult to associate two separately received pseudonyms with the same station, because the silent period disrupts the temporal and/or spatial correlation between two separately received pseudonyms, and obscures the time and place where a pseudonym changed. we generalizes a wireless LAN system into a MIX based anonymity model. The model offers two insights: a way of evaluating location privacy protection systems; and serving as a bridge between the new location privacy protection problem and existing defense and attack approaches in the MIX related research.