The multiple access channel with an untrusted relay (original) (raw)
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The multiple access channel with an untrusted relay,’’ presented at the
2014
Abstract-This paper considers a Gaussian multiple access channel aided by a relay. Specifically, the relay facilitates communication between multiple sources and a destination to which the sources have no direct link. In this set up, the relay node is considered to be untrusted, i.e., honest but curious, from whom the source messages need to be kept secret. We identify an achievable secrecy rate region utilizing cooperative jamming from the destination, and using compress-and-forward at the relay. Additionally, an outer bound on the secrecy rate region is derived. Numerical results indicate that the outer bound is tight in some cases of interest.
The Two-Hop Interference Untrusted-Relay Channel with Confidential Messages
—This paper considers the two-user interference relay channel where each source wishes to communicate to its destination a message that is confidential from the other destination. Furthermore, the relay, that is the enabler of communication, due to the absence of direct links, is untrusted. Thus, the messages from both sources need to be kept secret from the relay as well. We provide an achievable secure rate region for this network. The achievability scheme utilizes structured codes for message transmission, cooperative jamming and scaled compute-and-forward. In particular, the sources use nested lattice codes and stochastic encoding, while the destinations jam using lattice points. The relay decodes two integer combinations of the received lattice points and forwards, using Gaussian codewords, to both destinations. The achievability technique provides the insight that we can utilize the untrusted relay node as an encryption block in a two-hop interference relay channel with confidential messages.
Two-Hop Untrusted Relay Channel with an External Eavesdropper under Layered Secrecy Constraints
2016 IEEE Global Communications Conference (GLOBECOM), 2016
We consider a Gaussian network consisting of a source that aims to communicate to its legitimate destination via an untrusted relay node in the presence of an external eavesdropper. The source wishes to send two independent messages to the destination: one message must be kept secret from the external eavesdropper only, while the other message must be kept secret from the external eavesdropper and the untrusted relay both. We identify achievable secure rates under these layered secrecy constraints. Considering a two-hop half-duplex setup, we employ the destination as a cooperative jammer in the first phase in order to help provide secrecy from the relay and the external eavesdropper, and the source as a cooperative jammer in the second phase in order to detriment the external eavesdropper. The source encodes its messages using stochastic encoding and security embedding coding. We provide the secrecy analysis and present numerical results to demonstrate the performance of the propose...
IEEE Transactions on Information Theory, 2000
The General Gaussian Multiple Access Wire-Tap Channel (GGMAC-WT) and the Gaussian Two-Way Wire-Tap Channel (GTW-WT) are considered. In the GGMAC-WT, multiple users communicate with an intended receiver in the presence of an eavesdropper who receives their signals through another GMAC. In the GTW-WT, two users communicate with each other over a common Gaussian channel, with an eavesdropper listening through a GMAC. A secrecy measure that is suitable for this multi-terminal environment is defined, and achievable secrecy rate regions are found for both channels. For both cases, the power allocations maximizing the achievable secrecy sum-rate are determined. It is seen that the optimum policy may prevent some terminals from transmission in order to preserve the secrecy of the system. Inspired by this construct, a new scheme, cooperative jamming, is proposed, where users who are prevented from transmitting according to the secrecy sum-rate maximizing power allocation policy "jam" the eavesdropper, thereby helping the remaining users. This scheme is shown to increase the achievable secrecy sum-rate. Overall, our results show that in multipleaccess scenarios, users can help each other to collectively achieve positive secrecy rates. In other words, cooperation among users can be invaluable for achieving secrecy for the system.
The Gaussian Multiple Access Wire-Tap Channel with Collective Secrecy Constraints
2006 IEEE International Symposium on Information Theory, 2006
We consider the Gaussian Multiple Access Wire-Tap Channel (GMAC-WT). In this scenario, multiple users communicate with an intended receiver in the presence of an intelligent and informed wire-tapper who receives a degraded version of the signal at the receiver. We define a suitable security measure for this multi-access environment. We derive an outer bound for the rate region such that secrecy to some pre-determined degree can be maintained. We also find, using Gaussian codebooks, an achievable such secrecy region. Gaussian codewords are shown to achieve the sum capacity outer bound, and the achievable region concides with the outer bound for Gaussian codewords, giving the capacity region when inputs are constrained to be Gaussian. We present numerical results showing the new rate region and compare it with that of the Gaussian Multiple-Access Channel (GMAC) with no secrecy constraints.
The gaussian two-way relay channel with wiretapper
asilomar conference on signals, systems and computers, 2011
Secrecy capacity is analyzed in a Gaussian twoway relay wiretap channel (TRWC), where two legitimate source nodes wish to exchange their messages through a relay in the presence of an eavesdropper. We assume that all intended nodes operate in full-duplex mode and there is no direct path between two sources. In the Gaussian TRWC, we propose an achievable coding scheme composed of superposed lattice codes with both structured and random codebooks. A jamming strategy is further introduced at the two sources as well as at the relay to maximize the achievable secrecy rate regions, where each node allocates part of its power to jam the eavesdropper. Our result indicates that positive achievable secrecy rates are maintained even for the reversely degraded scenario. In addition, assuming two sources with equal power constraint, it is shown that the scheme asymptotically achieves within 1/2 bit from the cut-set bound based on the channel with no secrecy constraints, as the downlink phase is in the high signal-to-noise ratio regime.
Achievable rates for the general Gaussian multiple access wire-tap channel with collective secrecy
2006
We consider the General Gaussian Multiple Access Wire-Tap Channel (GGMAC-WT). In this scenario, multiple users communicate with an intended receiver in the presence of an intelligent and informed eavesdropper who is as capable as the intended receiver, but has different channel parameters. We aim to provide perfect secrecy for the transmitters in this multi-access environment. Using Gaussian codebooks, an achievable secrecy region is determined and the power allocation that maximizes the achievable sum-rate is found. Numerical results showing the new rate region are presented. It is shown that the multiple-access nature of the channel may be utilized to allow users with zero single-user secrecy capacity to be able to transmit in perfect secrecy. In addition, a new collaborative scheme is shown that may increase the achievable sum-rate. In this scheme, a user who would not transmit to maximize the sum rate can help another user who (i) has positive secrecy capacity to increase its rate, or (ii) has zero secrecy capacity to achieve a positive secrecy capacity.
Achievable secrecy rates over MIMOME Gaussian channels with GMM signals in low-noise regime
2014 4th International Conference on Wireless Communications, Vehicular Technology, Information Theory and Aerospace & Electronic Systems (VITAE), 2014
We consider a wiretap multiple-input multipleoutput multiple-eavesdropper (MIMOME) channel, where agent Alice aims at transmitting a secret message to agent Bob, while leaking no information on it to an eavesdropper agent Eve. We assume that Alice has more antennas than both Bob and Eve, and that she has only statistical knowledge of the channel towards Eve. We focus on the low-noise regime, and assess the secrecy rates that are achievable when the secret message determines the distribution of a multivariate Gaussian mixture model (GMM) from which a realization is generated and transmitted over the channel. In particular, we show that if Eve has fewer antennas than Bob, secret transmission is always possible at low-noise. Moreover, we show that in the low-noise limit the secrecy capacity of our scheme coincides with its unconstrained capacity, by providing a class of covariance matrices that allow to attain such limit without the need of wiretap coding.
On Maximizing the Secrecy Rate in a Cooperative Wireless Network using Friendly Jammers
International Journal of Information and Communication Technology Research, 2016
In this paper, the security of two-phase relaying system with multiple intermediate nodes in the presence of a malicious eavesdropper is investigated. To enhance the secrecy, a joint cooperative beamforming and jamming combined with relay and jammer selection is proposed. First, the source broadcasts its signal to the relays that are located close to source in a cluster, i.e., the source node uses a small amount of power to broadcast its message locally to other nodes of the cluster, while destination and the eavesdropper are located outside this cluster. In the second phase, two relays transmit re-encoded signal with optimal beamforming such that the secrecy rate is maximized. Simultaneously, two other intermediate nodes (which act as friendly jammers) transmit random jamming signals to degrade the eavesdropper's channel. Our goal in this paper is to maximize the secrecy rate by applying different methods such as cooperative beamforming, cooperative jamming and relay and jammer selection. To avoid operational complexity, we consider the minimum number of intermediate nodes needed for relaying and jamming without losing the performance, i.e., achieving a non-zero secrecy rate. Cooperative beamforming with multiple relays demands high amount of information exchange and therefore increases the operational complexity. Thus, we aim to reduce the number of relays which take part in cooperative beamforming. Limiting the number of relays may have a bad effect on the coding gain which we compensate it with a proposed selection gain scheme. Numerical results demonstrate the advantage of our proposed scheme compared to the scheme with no cooperative jamming. The main contribution of this work is combining cooperative beamforming and jamming with relay and jammer selection to enhance the physical layer security.
Improving secrecy rate via cooperative jamming based on Nash Equilibrium
2016 24th European Signal Processing Conference (EUSIPCO), 2016
This paper investigates the achievable secrecy regions when employing a friendly jammer in a cooperative scenario employing an untrusted relay. The untrusted relay which helps to forward the source signal towards the destination, could also be regarded as a potential eavesdropper. Our system employs a friendly jammer which sends a known noise signal towards the relay. In this paper, we investigate the effect of jammer and relay locations on the achievable secrecy rate. We consider two scenarios where in the first case we consider no direct transmission between the source and destination, while in the second case we include a source to destination direct link in our communication system.