We consider a set of users communicating over a Gaussian multiple access channel in the presence of an eavesdropper. The information theoretic secrecy rates for such settings have been well studied under the assumptions that all users are cooperative. In more recent work, a game theoretic model was studied in which each user selected its own rate. This game was shown to have multiple possible equilibria. Here, we consider a related question in which a mechanism is used to solicit information from the users and then allocate secrecy rates among them. We study three simple mechanisms and analyze the performance of each for a small set of users (N = 2, 3) in terms of their worst-case efficiency. For N = 2, we give a closed form lower bound on the efficiency for each scheme and show one mechanism, which generalizes the well-known Kelly mechanism, has the best efficiency. We then consider N = 3 users and give numerical results for different user utility functions.
A secure communication game is considered for the two-user MISO Gaussian interference channel with confidential messages, where each transmitter aims to maximize the difference between its secrecy rate and the secrecy rate of the other transmitter. In this novel problem, the weaker link tries to minimize the extra secret information obtained by its adversary, while the stronger link attempts to maximize it. We provide an information theoretic formulation for this non-cooperative zero-sum game scenario and determine that, under the assumption of Gaussian signaling at the transmitters, there exists a unique Nash equilibrium solution for the proposed problem. Moreover, we obtain in closed-form the optimal strategies (beamformers) at the transmitters that result in the Nash equilibrium. While the NE strategies are achievable in one shot when full channel state information is available at the transmitters (CSIT), we also propose an iterative step-by-step algorithm that converges to the NE point, but only requires limited CSIT. Numerical results are presented to illustrate the analytical findings and to study the role of different channel parameters on the NE strategies.
In this chapter, we propose game-theoretic models for resource allocation in interference channels with physical layer security. Three two-user interference channel scenarios are studied: the peaceful system with public messages, the case with private messages and forward secrecy, and the case with a public feedback channel. These lead to achievable rate, achievable secrecy, and achievable secret-key regions. Next, the outcome of a strategic game in normal form is computed and it is shown that either there exists an equilibrium in dominant strategies or a Nash equilibrium. Finally, three cooperative game models are applied: the Nash bargaining solution, a strategic bargaining algorithm, and the Walrasian market model. They are applicable to all three interference channel scenarios. Numerical illustrations show the utility regions and the outcomes from the different game models are discussed.
A Gaussian multiple access wire-tap channel with confidential messages is studied, where multiple users attempt to transmit private messages to a legitimate receiver in the presence of an eavesdropper. While prior work focused on the case where the users were cooperative, we assume that each user is selfish and and so are modeled as playing a non-cooperative game. We assume all users send a superposition of two Gaussian codebooks: one for their confidential messages and one for “filling” the evesdropper's channel. For such a scheme, we give a characterization of the achievable rate region defined by Tekin and Yener using polymatroid properties. We then use this to find the Nash equilibrium region for this non-cooperative game. Furthermore, we give algorithms for finding the best and worst Nash equilibria for a given channel.
In this paper, we study the two-user one-sided interference channel with confidential messages. In this interference channel, in addition to the usual selfishness of the users, the relationship between the two pairs of users is further adversarial in the sense of both receivers' desires to eavesdrop on the communication of the other pair. We develop a game-theoretic model to study the information-theoretic secure communications in this setting. We first start with a game-theoretic model where each pair's payoff is their own secrecy rate. The analysis of the binary deterministic interference channel with this payoff function shows that self-jamming of a transmitter, which injures the eavesdropping ability of its own receiver, is not excluded by the Nash equilibria. We propose a refinement for the payoff function by explicitly accounting for the desire of the receiver to eavesdrop on the other party's communication. This payoff function captures the adversarial relationship between the two pairs of users better. We determine the Nash equilibria for the binary deterministic channel for both payoff functions.
This paper studies the problem of secure communication over a
K -transmitter multiple access channel (MAC) in the presence of an external eavesdropper, subject to a collective secrecy constraint (i.e., information leakage rate to an eavesdropper on a collection of messages that are from a pre-specified subset of the
K transmitters, say
S⊆K={1,2,…,K} , is made vanishing). Since secrecy is of concern only to transmitters
{i∣i∈S} but not to transmitters
{i∣i∈Sc} , where
Sc=K\S , different transmission strategies could be employed at transmitters
{i∣i∈Sc} . Consider the following two scenarios: 1) transmitters
{i∣i∈Sc} use deterministic encoders (which are conventionally used for MAC without secrecy), competing for the channel resource (i.e., being competitive) and 2) transmitters
{i∣i∈Sc} use stochastic encoders, helping to hide other transmitters’ messages from the eavesdropper (i.e., being cooperative). As a result, we establish the respective
S -collective secrecy achievable rate regions and demonstrate the advantage of being cooperative theoretically and numerically. To this end, in addition to the standard techniques, our results build upon two techniques. The first is a generalization of Chia-El Gamal’s lemma on entropy bound for a set of codewords given partial information. The second is to utilize a compact representation of a list of sets that, together with submodular properties of mutual information functions involved, leads to an efficient Fourier-Motzkin elimination. These two approaches allow us to derive achievable regions in this work, and could also be of independent interest in other context.