Mechanisms to Mitigate Wireless Privacy Threats

The proliferation of mobile wireless devices enables or magnifies several privacy threats that traditional link layer confidentiality mechanisms, such as payload en- cryption, do not protect against: user tracking, profil- ing, and traffic analysis. For example, it is well known that the exposure of long-lived, unique device addresses can be used to track users over time. Although these ad- dresses can easily be changed, more subtle features ex- posed in encrypted link layer traffic can be used to iden- tify and profile users as well. These features, which we call implicit identifiers, include identifiers used for ser- vice discovery, characteristics that encryption does not obscure, and protocol information in unencrypted head- ers. We propose mechanisms to remove these features from wireless link layer protocols without the loss of im- portant network functionality.