127,724 research outputs found
Stochastic network interdiction games
Thesis (Ph.D.)--Boston UniversityNetwork interdiction problems consist of games between an attacker and an intelligent network, where the attacker seeks to degrade network operations while the network adapts its operations to counteract the effects of the attacker. This problem has received significant attention in recent years due to its relevance to military problems and network security. When the attacker's actions achieve uncertain effects, the resulting problems become stochastic network interdiction problems. In this thesis, we develop new algorithms for the solutions of different classes of stochastic network interdiction problems.
We first focus on static network interdiction games where the attacker attacks the network once, which will change the network with certain probability. Then the network will maximize the flow from a given source to its destination. The attacker is seeking a strategy which minimizes the expected maximum flow after the attack. For this problem, we develop a new solution algorithm, based on parsimonious integration of branch and bound techniques with increasingly accurate lower bounds. Our method obtains solutions significantly faster than previous approaches in the literature.
In the second part, we study a multi-stage interdiction problem where the attacker can attack the network multiple times, and observe the outcomes of its past attacks before selecting a current attack. For this dynamic interdiction game, we use a model-predictive approach based on a lower bound approximation. We develop a new set of performance bounds, which are integrated into a modified branch and bound procedure that extends the single stage approach to multiple stages. We show that our new algorithm is faster than other available methods with simulated experiments.
In the last part, we study the nested information game between an intelligent network and an attacker, where the attacker has partial information about the network state, which refers to the availability of arcs. The attacker does not know the exact state, but has a probability distribution over the possible network states. The attacker makes several attempts to attack the network and observes the flows on the network. These observations will update the attacker's knowledge of the network and will be used in selecting the next attack actions. The defender can either send flow on that arc if it survived, or refrain from using it in order to deceive the attacker. For these problems, we develop a faster algorithm, which decomposes this game into a sequence of subgames and solves them to get the equilibrium strategy for the original game. Numerical results show that our method can handle large problems which other available methods fail to solve
Probability Distributions on Partially Ordered Sets and Network Interdiction Games
This article poses the following problem: Does there exist a probability
distribution over subsets of a finite partially ordered set (poset), such that
a set of constraints involving marginal probabilities of the poset's elements
and maximal chains is satisfied? We present a combinatorial algorithm to
positively resolve this question. The algorithm can be implemented in
polynomial time in the special case where maximal chain probabilities are
affine functions of their elements. This existence problem is relevant for the
equilibrium characterization of a generic strategic interdiction game on a
capacitated flow network. The game involves a routing entity that sends its
flow through the network while facing path transportation costs, and an
interdictor who simultaneously interdicts one or more edges while facing edge
interdiction costs. Using our existence result on posets and strict
complementary slackness in linear programming, we show that the Nash equilibria
of this game can be fully described using primal and dual solutions of a
minimum-cost circulation problem. Our analysis provides a new characterization
of the critical components in the interdiction game. It also leads to a
polynomial-time approach for equilibrium computation
Information Leakage Games
We consider a game-theoretic setting to model the interplay between attacker
and defender in the context of information flow, and to reason about their
optimal strategies. In contrast with standard game theory, in our games the
utility of a mixed strategy is a convex function of the distribution on the
defender's pure actions, rather than the expected value of their utilities.
Nevertheless, the important properties of game theory, notably the existence of
a Nash equilibrium, still hold for our (zero-sum) leakage games, and we provide
algorithms to compute the corresponding optimal strategies. As typical in
(simultaneous) game theory, the optimal strategy is usually mixed, i.e.,
probabilistic, for both the attacker and the defender. From the point of view
of information flow, this was to be expected in the case of the defender, since
it is well known that randomization at the level of the system design may help
to reduce information leaks. Regarding the attacker, however, this seems the
first work (w.r.t. the literature in information flow) proving formally that in
certain cases the optimal attack strategy is necessarily probabilistic
Bad Data Injection Attack and Defense in Electricity Market using Game Theory Study
Applications of cyber technologies improve the quality of monitoring and
decision making in smart grid. These cyber technologies are vulnerable to
malicious attacks, and compromising them can have serious technical and
economical problems. This paper specifies the effect of compromising each
measurement on the price of electricity, so that the attacker is able to change
the prices in the desired direction (increasing or decreasing). Attacking and
defending all measurements are impossible for the attacker and defender,
respectively. This situation is modeled as a zero sum game between the attacker
and defender. The game defines the proportion of times that the attacker and
defender like to attack and defend different measurements, respectively. From
the simulation results based on the PJM 5 Bus test system, we can show the
effectiveness and properties of the studied game.Comment: To appear in IEEE Transactions on Smart Grid, Special Issue on Cyber,
Physical, and System Security for Smart Gri
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