Gaussian Secure Source Coding and Wyner's Common Information

We study secure source-coding with causal disclosure, under the Gaussian distribution. The optimality of Gaussian auxiliary random variables is shown in various scenarios. We explicitly characterize the tradeoff between the rates of communication and secret key. This tradeoff is the result of a mutual information optimization under Markov constraints. As a corollary, we deduce a general formula for Wyner's Common Information in the Gaussian setting.Comment: ISIT 2015, 5 pages, uses IEEEtran.cl

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

Secure Strong Coordination

We consider a network of two nodes separated by a noisy channel, in which the source and its reconstruction have to be strongly coordinated, while simultaneously satisfying the strong secrecy condition with respect to an outside observer of the noisy channel. In the case of non-causal encoding and decoding, we propose a joint source-channel coding scheme for the secure strong coordination region. Furthermore, we provide a complete characterization of the secure strong coordination region when the decoder has to reliably reconstruct the source sequence and the legitimate channel is more capable than the channel of the eavesdropper

Capacity Bounds For Multi-User Channels With Feedback, Relaying and Cooperation

Recent developments in communications are driven by the goal of achieving high data rates for wireless communication devices. To achieve this goal, several new phenomena need to be investigated from an information theoretic perspective. In this dissertation, we focus on three of these phenomena: feedback, relaying and cooperation. We study these phenomena for various multi-user channels from an information theoretic point of view. One of the aims of this dissertation is to study the performance limits of simple wireless networks, for various forms of feedback and cooperation. Consider an uplink communication system, where several users wish to transmit independent data to a base-station. If the base-station can send feedback to the users, one can expect to achieve higher data-rates since feedback can enable cooperation among the users. Another way to improve data-rates is to make use of the broadcast nature of the wireless medium, where the users can overhear each other's transmitted signals. This particular phenomenon has garnered much attention lately, where users can help in increasing each other's data-rates by utilizing the overheard information. This overheard information can be interpreted as a generalized form of feedback. To take these several models of feedback and cooperation into account, we study the two-user multiple access channel and the two-user interference channel with generalized feedback. For all these models, we derive new outer bounds on their capacity regions. We specialize these results for noiseless feedback, additive noisy feedback and user-cooperation models and show strict improvements over the previously known bounds. Next, we study state-dependent channels with rate-limited state information to the receiver or to the transmitter. This state-dependent channel models a practical situation of fading, where the fade information is partially available to the receiver or to the transmitter. We derive new bounds on the capacity of such channels and obtain capacity results for a special sub-class of such channels. We study the effect of relaying by considering the parallel relay network, also known as the diamond channel. The parallel relay network considered in this dissertation comprises of a cascade of a general broadcast channel to the relays and an orthogonal multiple access channel from the relays to the receiver. We characterize the capacity of the diamond channel, when the broadcast channel is deterministic. We also study the diamond channel with partially separated relays, and obtain capacity results when the broadcast channel is either semi-deterministic or physically degraded. Our results also demonstrate that feedback to the relays can strictly increase the capacity of the diamond channel. In several sensor network applications, distributed lossless compression of sources is of considerable interest. The presence of adversarial nodes makes it important to design compression schemes which serve the dual purpose of reliable source transmission to legitimate nodes while minimizing the information leakage to the adversarial nodes. Taking this constraint into account, we consider information theoretic secrecy, where our aim is to limit the information leakage to the eavesdropper. For this purpose, we study a secure source coding problem with coded side information from a helper to the legitimate user. We derive the rate-equivocation region for this problem. We show that the helper node serves the dual purpose of reducing the source transmission rate and increasing the uncertainty at the adversarial node. Next, we considered two different secure source coding models and provide the corresponding rate-equivocation regions

Trust and Formal Control in interorganizational Relationships

There is a tendency to see trust and control by formal agreements as substitutes. According to transaction cost economics trust is unreliable, and some form of control is needed to reduce hazards of opportunism. According to others, high trust allows for a limited extent of formal control. Formal control signals distrust and thereby evokes reciprocal distrust and formal control. This paper studies all combinations of high/low trust and high/low formal control in four longitudinal case studies. We find that trust and formal control are at least as much complements as they are substitutes. We find that like trust contracts can be both the basis and the outcome of relations.governance;inter-organizational relations;trust;contract

Secure Data Retrieval using CP-ABE Scheme in Military networks

The absolute most difficult issues in this situation are the implementation of authorization policies and the policies refresh for secure information recovery. Cipher text-policy attribute-based encryption is a promising cryptographic answer for the entrance control issues. However, the issue of applying CP-ABE in decentralized DTNs presents a few securities and protection challenges as to the attribute revocation, key escrow, and coordination of attributes issued from various experts. In this paper, we propose a secure information recovery conspire utilizing CP-ABE for decentralized DTNs where numerous key specialists deal with their attributes independently. We show how to apply the proposed instrument to securely and effectively deal with the confidential information dispersed in the disruption-tolerant military network. Versatile hubs in military conditions, for example, a war zone or a threatening locale are probably going to experience the ill effects of irregular network availability and continuous parcels. Disruption-tolerant network advances are getting to be effective arrangements that permit remote gadgets conveyed by warriors to speak with one another and get to the confidential data or direction reliably by misusing outer capacity hubs

A Balanced Theory of Sourcing, Collaboration and Networks

In a synthesis of recent advances, this article gives a fresh, balanced theory of inter-organizational relations. It integrates competence and governance perspectives. It considers the choice between mergers/acquisitions and alliances. It offers a toolbox of instruments to govern relational risk, and the contingencies for their selection. Relationships can last too long. Therefore, the article also looks at how to end relationships. Beyond dyads of collaborating firms, it includes effects of network structure and position.corporate governance;inter-organizational relations;organizational behavior;inter-firm alliances;collaboration

Trust and Formal Control in interorganizational Relationships

There is a tendency to see trust and control by formal agreements as substitutes. According to transaction cost economics trust is unreliable, and some form of control is needed to reduce hazards of opportunism. According to others, high trust allows for a limited extent of formal control. Formal control signals distrust and thereby evokes reciprocal distrust and formal control. This paper studies all combinations of high/low trust and high/low formal control in four longitudinal case studies. We find that trust and formal control are at least as much complements as they are substitutes. We find that like trust contracts can be both the basis and the outcome of relations