The Influence of Secrecy on the Communication Structure of Covert Networks

In order to be able to devise successful strategies for destabilizing terrorist organizations it is vital to recognize and understand their structural properties. This paper deals with the opti- mal communication structure of terrorist organizations when considering the tradeoff between secrecy and operational efficiency. We use elements from game theory and graph theory to determine the `optimal' communication structure a covert network should adopt. Every covert organization faces the constant dilemma of staying secret and ensuring the necessary coordina- tion between its members. For several different secrecy and information scenarios this dilemma is modeled as a game theoretic bargaining problem over the set of connected graphs of given order. Assuming uniform exposure probability of individuals in the network we show that the Nash bargaining solution corresponds to either a network with a central individual (the star graph) or an all-to-all network (the complete graph) depending on the link detection probabil- ity, which is the probability that communication between individuals will be detected. If the probability that an individual is exposed as member of the network depends on the information hierarchy determined by the structure of the graph, the Nash bargaining solution corresponds to cellular-like networks.