Conventional physical layer (PHY) security assumes unencrypted transmissions, requiring zero information leakage to adversaries. By incorporating encryption, this constraint can be relaxed, enabling higher secure transmission rates while tolerating limited leakage. This paper investigates an encryption-aware power allocation strategy and achievable transmission rate of a Gaussian wiretap channel in the presence of multiple cooperative jammers. By analyzing the rate-equivocation region and the corresponding rate maximization problem, optimal cooperative jamming strategy that maximizes the encryption-aware secrecy capacity is first addressed. The encryption-aware rate maximization problem is then shown to be equivalent to a non-convex beamforming vector optimization under a non-linear constraint, which is explicitly solved. Our numerical results illustrate that by utilizing the prior knowledge of encryption, optimizing the power allocation among jamming nodes significantly enhances the achievable secrecy rates.
Conventional physical layer (PHY) security assumes unencrypted transmissions, requiring zero information leakage to adversaries. By incorporating encryption, this constraint can be relaxed, enabling higher secure transmission rates while tolerating limited leakage. This paper investigates an encryption-aware power allocation strategy and achievable transmission rate of a Gaussian wiretap channel in the presence of multiple cooperative jammers. By analyzing the rate-equivocation region and the corresponding rate maximization problem, optimal cooperative jamming strategy that maximizes the encryption-aware secrecy capacity is first addressed. The encryption-aware rate maximization problem is then shown to be equivalent to a non-convex beamforming vector optimization under a non-linear constraint, which is explicitly solved. Our numerical results illustrate that by utilizing the prior knowledge of encryption, optimizing the power allocation among jamming nodes significantly enhances the achievable secrecy rates.
In conventional physical layer security schemes no leakage of private information to adversary nodes is tolerated, and no assumption on the encryption of information is considered. This is a limiting assumption in physical layer security, which compromises the efficiency of such schemes. This paper introduces an approach in which a prior knowledge of encryption can be used to improve the security performance of cooperative jamming in Gaussian wiretap channels as an example of physical layer security approached. The proposed approach, however, is not limited to the considered scenario of cooperative jamming and can be applied to other scenarios. We consider a system composed of a transmitter, a receiver, and eavesdropper and several jamming nodes that work independently, and formulate an optimization problem to maximize the secrecy rate with the knowledge of encryption and attempt to solve it by driving the rate-equivocation region to constrain and determine the feasibility of the solution. We then exploit a linear approximation to solve the resulted nonconvex optimization problem to maximize the secure transmission rate. Our numerical results show that prior knowledge of encryption can be exploited to allocate the available power to the jamming nodes to significantly increase the secure transmission rate.
In traditional physical layer security paradigm, no leakage of confidential information to the eavesdropper is tolerated regardless of whether the message is encrypted or not. This will result in an achievable secure transmission rate that is significantly smaller than the channel capacity. This article presents a novel approach that allows treatment of physical layer security in conjunction with encryption to achieve a flexible trade-off of system resources. We propose a novel framework to model the interplay between secured transmission rate and error probability in error prone ciphertexts. To this end, we use the concept of rate-equivocation region to establish such a connection. To clearly describe the application of our framework, we consider the case of 4-node Gaussian wiretap channel. For such a channel, we characterize the rate-equivocation region in different scenarios, and then use it to study the achievable rate of encryption-aware physical layer security. The obtained results show that, for a fixed transmission power, the prior knowledge of encryption can significantly increase the secured transmission rate. In addition, encryption-aware physical layer security can achieve a target transmission rate at a reduced transmission power compared to the conventional encryption-agnostic physical layer security.
In this work, we propose a joint security approach based on physical layer security (PhySec) and noisy ciphertext to improve the secrecy rate of a relay network with cooperative jamming via two trusted relays. While the secrecy capacity has been considered as the maximum limit for a perfect secrecy at the physical layer, we demonstrate that the consideration of error- prone ciphertext in encryption and its interaction with PhySec allows us to transmit above the PhySec capacity without any leakage. By formulating and solving a non-convex encryption- aided secrecy rate maximization problem, it is shown that beyond PhySec capacity performances can be achieved even in a simple jamming scenario in which the two jammers just send independent jamming signals. The optimal encryption-aware power allocation and the secrecy rate maximization solution are also established in the case of common jamming signals to further increase the secrecy rate. Numerical results are finally provided to demonstrate the superiority of the proposed joint security framework over traditional PhySec.
Cooperative jamming approach has been commonly used in the field of physical layer security to achieve a good secrecy rate of wireless networks. In this approach, the Gaussian noise signal sent by a friendly jammer can disrupt the reception of the eavesdropper, however, it may also interfere with the legitimate receiver. In this paper, we propose a novel approach, namely, information jamming, to go beyond the secrecy rate achieved by the traditional cooperative jamming approach in a multiple-input single-output (MISO) wiretap channel. We propose that a multi-antenna friendly jammer transmits the source message rather than Gaussian noise signal for simultaneously enhancing the signal strength at the legitimate receiver and canceling the received signal at the eavesdropper. In particular, we aim to maximize the achievable secrecy rate by optimizing the information jammer's beamforming vector. Though the optimization problem is non-convex, we successfully solve it optimally via a two-stage based numerical approach. To gain more useful analytical results, we also propose two suboptimal jamming schemes with low computation, by targeting at improving the legitimate reception and avoiding the eavesdropping, respectively. Finally, numerical results show that the proposed information jamming approach significantly helps go beyond the secrecy rate of the existing cooperative jamming approach, especially when the transmit power of the jammer is large enough.
In this paper, we investigate a cooperative jamming strategy combined with a null-steering beamforming technique (CJ-NB strategy) for physical-layer security. To evaluate the achievable secrecy rate, the source input distribution is assumed to be Gaussian, and the achievable secrecy rate can be formulated as an optimization problem for power allocation (PA). By solving the problem, an asymptotically optimal PA is obtained with an exactly closed-form expression. In addition, we provide an asymptotic analysis of the achievable secrecy rate. The asymptotic result shows that the achievable secrecy rate is linearly proportional to the signal-to-noise ratio, but it will become saturated when the number of jammers is high enough. Therefore, we then develop a simple and efficient jammer selection algorithm to find an appropriate jamming set to achieve almost the same performance, but significantly reduce the number of jammers used compared with all the jammers performing the CJ-NB strategy. Finally, we provide simulation results to support our analyses.
This paper studies the secrecy rate maximization problem of a secure wireless communication system in the presence of multiple eavesdroppers. The security of the communication link is enhanced through cooperative jamming with the help of multiple jammers. First, a feasibility condition is derived to achieve a positive secrecy rate at the destination. Then, we solve the original secrecy rate maximization problem, which is not convex in terms of power allocation at the jammers. To circumvent this nonconvexity, the achievable secrecy rate is approximated for a given power allocation at the jammers, and the approximated problem is formulated into a geometric programming one. Based on this approximation, an iterative algorithm has been developed to obtain the optimal power allocation at the jammers. Next, we provide a bisection approach, based on 1-D search, to validate the optimality of the proposed algorithm. In addition, by assuming Rayleigh fading, the secrecy outage probability (SOP) of the proposed cooperative jamming scheme is analyzed. More specifically, a single-integral form expression for the SOP is derived for the most general case, as well as a closed-form expression for the special case of two cooperative jammers and one eavesdropper. Simulation results have been provided to validate the convergence and the optimality of the proposed algorithm, as well as the theoretical derivations of the presented SOP analysis.