More Like this

1. Gaussian Multiuser Wiretap Channels in the Presence of a Jammer-Aided Eavesdropper

   https://doi.org/10.3390/e24111595  

   Chou, Rémi A.; Yener, Aylin (November 2022, Entropy)

   This paper considers secure communication in the presence of an eavesdropper and a malicious jammer. The jammer is assumed to be oblivious of the communication signals emitted by the legitimate transmitter(s) but can employ any jamming strategy subject to a given power constraint and shares her jamming signal with the eavesdropper. Four such models are considered: (i) the Gaussian point-to-point wiretap channel; (ii) the Gaussian multiple-access wiretap channel; (iii) the Gaussian broadcast wiretap channel; and (iv) the Gaussian symmetric interference wiretap channel. The use of pre-shared randomness between the legitimate users is not allowed in our models. Inner and outer bounds are derived for these four models. For (i), the secrecy capacity is obtained. For (ii) and (iv) under a degraded setup, the optimal secrecy sum-rate is characterized. Finally, for (iii), ranges of model parameter values for which the inner and outer bounds coincide are identified. 

   more » « less
2. A Cross-Layer Security Approach for Multi-Node Gaussian Wiretap Channels

   Tran, Nghi (May 2025, 7th International Symposium on Signal Processing Systems)

   In this work, we propose a new approach to examine the joint effect of physical layer security (PhySec) and encryption. Our idea relies on the concept of rate-equivocation regions and can be used to study the tradeoff between encryption strength, allowed leakage, and transmission rate. By considering encryption, it is possible to achieve transmission rates beyond the secrecy capacity that is achievable by conventional physical layer security. Toward our goal, we exploit the fact that cryptography undermines the ability of the eavesdropper to access the plaintext. We then relax the design of physical layer security schemes without compromising the security of the system. To validate our new approach, we consider a multi-node Gaussian wiretap channel consisting of a legitimate transmitter, a legitimate receiver, an eavesdropper and multiple trusted relays assisting transmission from the transmitter to the receiver. Under this wireless network, we illustrate that encryption awareness not only complements traditional PhySec methods but also achieves superior secrecy performance. An encryption-aware secrecy capacity was also obtained from the rate-equivocation regions under different channel state information conditions. 

   more » « less
3. A Cooperative Jamming Game in Wireless Networks under Uncertainty

   https://doi.org/10.1007/978-3-030-63086-7_14  

   Xu, Z.; Baykal-Gürsoy, M. (December 2020, Security and Privacy in Communication Networks. SecureComm 2020. Lecture Notes)

   null (Ed.)

   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. 

   more » « less
4. MIMO wiretap channel with ISI heterogeneity — Achieving secure DoF with no CSI

   https://doi.org/10.1109/ACSSC.2017.8335647  

   de Dieu Mutangana, Jean; Kumar, Deepak; Tandon, Ravi (October 2017, 51st Asilomar Conference on Signals, Systems, and Computers)

   We consider the multiple-input multiple-output (MIMO) wiretap channel with intersymbol interference (ISI) in which a transmitter (Alice) wishes to securely communicate with a receiver (Bob) in presence of an eavesdropper (Eve). We focus on the practically relevant setting in which there is no channel state information (CSI) at Alice about either of the channels to Bob or Eve, except statistical information about the ISI channels (i.e., Alice only knows the effective number of ISI taps). The key contribution of this work is to show that even with no CSI at Alice, positive secure degrees of freedom (SDoF) are achievable by carefully exploiting a) the heterogeneity of the ISI links to Bob and Eve, and b) the relative number of antennas at all the three terminals. To this end, we propose a novel achievable scheme that carefully mixes information and artificial noise symbols in order to exploit ISI heterogeneity to achieve positive SDoF. To the best of our knowledge, this is the first work to explore the idea of exploiting ISI channel length heterogeneity to achieve positive SDoF for the MIMO wiretap channel with no CSI at the legitimate transmitter. 

   more » « less
5. Keyless Covert Communication in the Presence of Non-causal Channel State Information

   Zivari-Fard, H.; Bloch, M.; Nosratinia, A. (August 2019, IEEE Information Theory Workshop)

   We consider the problem of covert communication over a state-dependent channel, for which the transmitter and the legitimate receiver have non-causal access to the channel state information. Covert communication with respect to an adversary, referred to as the “warden,” is one in which the distribution induced during communication at the channel output observed by the warden is identical to the output distribution conditioned on an inactive channel-input symbol. Covert communication involves fooling an adversary in part by a proliferation of codebooks; for reliable decoding at the legitimate receiver the codebook uncertainty is removed via a shared secret key that is unavailable to the warden. Unlike earlier work in state-dependent covert communication, we do not assume the availability of a shared key at the transmitter and legitimate receiver. Rather, a shared randomness is extracted at the transmitter and the receiver from the channel state, in a manner that keeps the shared randomness secret from the warden despite the influence of the channel state on the warden’s output. An inner bound on the covert capacity, in the absence of an externally provided secret key, is derived. 

   more » « less