1,433 research outputs found
Principles of Physical Layer Security in Multiuser Wireless Networks: A Survey
This paper provides a comprehensive review of the domain of physical layer
security in multiuser wireless networks. The essential premise of
physical-layer security is to enable the exchange of confidential messages over
a wireless medium in the presence of unauthorized eavesdroppers without relying
on higher-layer encryption. This can be achieved primarily in two ways: without
the need for a secret key by intelligently designing transmit coding
strategies, or by exploiting the wireless communication medium to develop
secret keys over public channels. The survey begins with an overview of the
foundations dating back to the pioneering work of Shannon and Wyner on
information-theoretic security. We then describe the evolution of secure
transmission strategies from point-to-point channels to multiple-antenna
systems, followed by generalizations to multiuser broadcast, multiple-access,
interference, and relay networks. Secret-key generation and establishment
protocols based on physical layer mechanisms are subsequently covered.
Approaches for secrecy based on channel coding design are then examined, along
with a description of inter-disciplinary approaches based on game theory and
stochastic geometry. The associated problem of physical-layer message
authentication is also introduced briefly. The survey concludes with
observations on potential research directions in this area.Comment: 23 pages, 10 figures, 303 refs. arXiv admin note: text overlap with
arXiv:1303.1609 by other authors. IEEE Communications Surveys and Tutorials,
201
Routing for Security in Networks with Adversarial Nodes
We consider the problem of secure unicast transmission between two nodes in a
directed graph, where an adversary eavesdrops/jams a subset of nodes. This
adversarial setting is in contrast to traditional ones where the adversary
controls a subset of links. In particular, we study, in the main, the class of
routing-only schemes (as opposed to those allowing coding inside the network).
Routing-only schemes usually have low implementation complexity, yet a
characterization of the rates achievable by such schemes was open prior to this
work. We first propose an LP based solution for secure communication against
eavesdropping, and show that it is information-theoretically rate-optimal among
all routing-only schemes. The idea behind our design is to balance information
flow in the network so that no subset of nodes observe "too much" information.
Interestingly, we show that the rates achieved by our routing-only scheme are
always at least as good as, and sometimes better, than those achieved by
"na\"ive" network coding schemes (i.e. the rate-optimal scheme designed for the
traditional scenario where the adversary controls links in a network rather
than nodes.) We also demonstrate non-trivial network coding schemes that
achieve rates at least as high as (and again sometimes better than) those
achieved by our routing schemes, but leave open the question of characterizing
the optimal rate-region of the problem under all possible coding schemes. We
then extend these routing-only schemes to the adversarial node-jamming
scenarios and show similar results. During the journey of our investigation, we
also develop a new technique that has the potential to derive non-trivial
bounds for general secure-communication schemes
Securing Large-Scale D2D Networks Using Covert Communication and Friendly Jamming
We exploit both covert communication and friendly jamming to propose a
friendly jamming-assisted covert communication and use it to doubly secure a
large-scale device-to-device (D2D) network against eavesdroppers (i.e.,
wardens). The D2D transmitters defend against the wardens by: 1) hiding their
transmissions with enhanced covert communication, and 2) leveraging friendly
jamming to ensure information secrecy even if the D2D transmissions are
detected. We model the combat between the wardens and the D2D network (the
transmitters and the friendly jammers) as a two-stage Stackelberg game.
Therein, the wardens are the followers at the lower stage aiming to minimize
their detection errors, and the D2D network is the leader at the upper stage
aiming to maximize its utility (in terms of link reliability and communication
security) subject to the constraint on communication covertness. We apply
stochastic geometry to model the network spatial configuration so as to conduct
a system-level study. We develop a bi-level optimization algorithm to search
for the equilibrium of the proposed Stackelberg game based on the successive
convex approximation (SCA) method and Rosenbrock method. Numerical results
reveal interesting insights. We observe that without the assistance from the
jammers, it is difficult to achieve covert communication on D2D transmission.
Moreover, we illustrate the advantages of the proposed friendly
jamming-assisted covert communication by comparing it with the
information-theoretical secrecy approach in terms of the secure communication
probability and network utility
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Analog Cancellation of a Known Remote Interference: Hardware Realization and Analysis
The onset of quantum computing threatens commonly used schemes for information secrecy across wireless communication channels, particularly key-based data-level encryption. This calls for secrecy schemes that can provide everlasting secrecy resistant to increased computational power of an adversary. One novel physical layer scheme proposes that an intended receiver capable of performing analog cancellation of a known key-based interference would hold a significant advantage in recovering small underlying messages versus an eavesdropper performing cancellation after analog-to-digital conversion. This advantage holds even in the event that an eavesdropper can recover and use the original key in their digital cancellation. Inspired by this scheme, a flexible software-defined radio receiver design capable of maintaining analog cancellation ratios consistently over 40 dB, reaching up to and over 50 dB, is implemented in this thesis. Maintaining this analog cancellation requires very precise time-frequency synchronization along with accurate modeling and simulation of the channel effects on the interference. The key sources of synchronization error preventing this test bed from achieving and maintaining perfect interference cancellation, sub-sample period timing errors and limited radio frequency stability, are explored for possible improvements.
To further prove robustness of the implemented secrecy scheme, the testbed is shown to operate with both phase-shift keying and frequency-modulated waveforms. Differences in the synchronization algorithm used for the two waveforms are highlighted. Interference cancellation performance is measured for increasing interference bandwidth and shown to decrease with such.
The implications this testbed has on security approaches based on intentional interference employed to confuse eavesdroppers is approached from the framework proposed in the motivating everlasting secrecy scheme. Using analog cancellation levels from the hardware testbed, it is calculated that secrecy rates up to 2.3 bits/symbol are gained by receivers (intended or not) performing interference cancellation in analog rather than on a digital signal processor.
Inspired by the positive gains in secrecy over systems not performing analog cancellation prior to signal reception, a novel secrecy scheme that focuses on the advantage an analog canceller holds in receiver amplifier compression is proposed here. The adversary amplifier is assumed to perform linear cancellation after the interference has passed through their nonlinear amplifier. This is accomplished by deriving the distribution of the interference residual after undergoing an inverse tangent transfer function and perfect linear cancellation. Parameters of this scheme are fit for the radios and cancellation ratios observed in the testbed, resulting in a secrecy gain of 0.95 bits/symbol. The model shows that larger message powers can still be kept secure for the achieved levels of cancellation, thus providing an even greater secrecy gain with increased message transmission power
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