On Size Hiding Protocols in Beeping Model.

Execution of a protocol in a wireless sensor network may reveal some information about its size. For example, the time required to elect a leader or establish size approximation using the most popular protocols is strongly correlated with the number of participating stations. This property may be very undesirable in many natural scenarios, like e.g., the military area of applications. This paper considers how much information about the network size a passive adversary eavesdropping on the communication channel can learn from the protocol execution. We formalize this problem in a general form (modeling the system as a multiple access channel with various feedbacks) and then present some practical results for the popular beeping model. In particular, we demonstrate how to construct a universal method that provably conceals the exact number of participating stations. Moreover, we explain the limitations of the presented approach. Finally, we show that in the case of some particular problems, the size-hiding property can be archived without any additional activities.