On the tradeoffs between network state knowledge and secrecy

In this paper, the impact of network-state knowledge on the feasibility of secrecy is studied in the context of non-colluding active eavesdropping. The main contribution is the investigation of several scenarios in which increasing the available knowledge at each of the network components leads to some paradoxical observations in terms of the average secrecy capacity and average information leakage. These observations are in the context of a broadcast channel similar to the time-division downlink of a single-cell cellular system. Here, providing more knowledge to the eavesdroppers makes them more conservative in their attacks, and thus, less harmful in terms of average information leakage. Similarly, providing more knowledge to the transmitter makes it more careful and less willing to transmit, which reduces the expected secrecy capacity. These findings are illustrated with a numerical analysis that shows the impact of most of the network parameters in the feasibility of secrecy.