Eavesdropper Localization in Random Walk Channels

Eavesdroppers are notoriously difficult to detect and locate in traditional wireless communication systems, especially if they are silent. We show that in molecular communications, where information molecules undergo random walk (RW) propagation, eavesdropper detection and localization are possible if the eavesdropper is an absorbing receiver. This is due to the fact that the RW process has a finite return probability, and the eavesdropper is a detectable energy sink of which its location can be reverse estimated.