Optimal strategies for dynamic weight selection in consensus protocols in the presence of an adversary

In this paper, we consider optimal design strategies in consensus protocols for networks vulnerable to adversarial attacks. First we study dynamic (multi-stage) weight selection optimal control for consensus protocols. For the general (multi-stage) case, the solution exists but can rarely be expressed in closed-form. In view of this, we apply optimization techniques to obtain a locally (and possibly globally) optimizing feasible control path. For the one-stage case, however, we obtain a closed-form solution for the optimal control and provide sufficient conditions for the existence of a control that makes the system reach consensus in only one iteration. We then consider a game theoretical model for the problem of a network with an adversary corrupting the control signal with noise. We derive the optimal strategies for both players (the adversary and the network designer) of the resulting game using a saddle point equilibrium (SPE) solution in mixed strategies.