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  1. Free, publicly-accessible full text available October 3, 2023
  2. Considered is a network of parallel wireless channels in which individual parties are engaged in secret communication under the protection of cooperative jamming. A strategic eavesdropper selects the most vulnerable channels to attack. Existing works usually suggest the defender allocate limited cooperative jamming power to various channels. However, it usually requires some strong assumptions and complex computation to find such an optimal power control policy. This paper proposes a probabilistic cooperative jamming scheme such that the defender focuses on protecting randomly selected channels. Two different cases regarding each channel’s eavesdropping capacity are discussed. The first case studies the general scenario where each channel has different eavesdropping capacity. The second case analyzes an extreme scenario where all channels have the same eavesdropping capacity. Two non-zero-sum Nash games model the competition between the network defender and an eavesdropper in each case. Furthermore, considering the case that the defender does not know the eavesdropper’s channel state information (CSI) leads to a Bayesian game. For all three games, we derive conditions for the existence of a unique Nash equilibrium (NE), and obtain the equilibria and the value functions in closed form.
    Free, publicly-accessible full text available October 4, 2022
  3. Filipe J. ; Ghosh A. ; Prates R. O. ; Zhou L. (Ed.)
    This paper considers a parallel wireless network in which multiple individuals exchange confidential information through independent sender-receiver links. An eavesdropper can intercept encrypted information through a degraded channel of each sender-receiver link. A friendly jammer, by applying interference to the eavesdropping channels, can increase the level of secrecy of the network. The optimal power allocation strategy of the friendly jammer under a power constraint is derived. A convex optimization model is used when all channels are under the threat of an eavesdropping attack and a non-zero sum game model is analyzed when the eavesdropper can only attack a limited quantity of channels.
  4. This paper considers network protection games against different types of attackers for a heterogeneous network system with N units. A defender, by applying resources to networked units, can decrease the units’ vulnerabilities. At the same time, the defender needs to take into account the cost of using defense resources. Two non-zero sum Nash games against two different types of attackers are studied. The first type tries to maximize damage based on the value of security assets related to networked units, while the second type aims at infiltrating the network. The analyses show that there exists a cut-off index determining the set of units that will be protected in the equilibrium strategies of the first game, while either all units or none will be covered in the equilibria of the second game. An application of the network protection game to secure wireless communication networks is presented.
  5. Considered is a multi-channel wireless network for secret communication that uses the signal-to-interference-plus-noise ratio (SINR) as the performance measure. An eavesdropper can intercept encoded messages through a degraded channel of each legitimate transmitter-receiver communication pair. A friendly interferer, on the other hand, may send cooperative jamming signals to enhance the secrecy performance of the whole network. Besides, the state information of the eavesdropping channel may not be known completely. The transmitters and the friendly interferer have to cooperatively decide on the optimal jamming power allocation strategy that balances the secrecy performance with the cost of employing intentional interference, while the eavesdropper tries to maximize her eavesdropping capacity. To solve this problem, we propose and analyze a non-zero-sum game between the network defender and the eavesdropper who can only attack a limited number of channels. We show that the Nash equilibrium strategies for the players are of threshold type. We present an algorithm to find the equilibrium strategy pair. Numerical examples demonstrate the equilibrium and contrast it to baseline strategies.
  6. Terrorist attacks carried out by individuals or single cells have significantly accelerated over the last 20 years. This type of terrorism, defined as lone-actor (LA) terrorism, stands as one of the greatest security threats of our time. Research on LA behavior and characteristics has emerged and accelerated over the last decade. While these studies have produced valuable information on demographics, behavior, classifications, and warning signs, the relationship among these characters are yet to be addressed. Moreover, the means of radicalization and attacking have changed over decades. This study first identifies 25 binary behavioral characteristics of LAs and analyzes 192 LAs recorded on three different databases. Next, the classification is carried out according to first ideology, then to incident scene behavior via a virtual attacker-defender game, and, finally, according to the clusters obtained from the data. In addition, within each class, statistically significant associations and temporal relations are extracted using the A-priori algorithm. These associations would be instrumental in identifying the attacker type and intervene at the right time. The results indicate that while pre-9/11 LAs were mostly radicalized by the people in their environment, post-9/11 LAs are more diverse. Furthermore, the association chains for different LA types present unique characteristicmore »pathways to violence and after-attack behavior.« less