Lower Secrecy Research Articles

Societal secrecy and ADR IPOs underpricing

This study examines 350 Level III ADR IPOs from 35 countries between 1990 and 2020 to explore the link between societal secrecy and IPO underpricing. Focusing on ADR IPOs, we hypothesize that firms from higher secrecy countries, compared to firms from low secrecy countries, benefit more from public offerings in a low secrecy country. U.S. investors might value these firms relatively more due to the reduction in information asymmetry and higher expected diversification benefits. The results support our hypothesis, showing that ADR IPO underpricing is lower for ADRs from high secrecy countries. These findings hold true across various measures and controls, ensuring robustness.

Cooperative Beamforming With Artificial Noise Injection for Physical-Layer Security

In the sixth-generation (6G) communications, how to deploy and manage massively connected Internet-of-Things (IoT) nodes will be one of the key technical challenges, because 6G is expected to provide 10 times higher connection, compared to 5G. At the same time, due to the sharp growth in connected devices and newly adopted technologies, learning-based attacks and big data breaches are expected to occur more frequently. With the advances of quantum computing in the future, conventional cryptography-based security protocols may be obsolete in the future wireless networks, which makes physical layer security (PLS) an attractive alternative or complement for secure communications. In this context, cooperative beamforming (CB)-based PLS schemes are known to be effective solutions to guarantee high secrecy rate with IoT devices, which have limited power and hardware complexity. However, the existing CB-based PLS algorithms suffer from extremely low secrecy rate, in case that eavesdroppers are close to the intended receiver. To overcome such critical issue, in this paper, we propose a CB-based PLS with artificial noise (AN) injection, which can be realized in a fully distributed manner to minimize the overhead in the IoT networks with a large number of devices. We analyze the array factor using the virtual antenna array (VAA) created by the proposed PLS algorithm. Then, the secrecy rate is derived in a closed-form expression, which can be used to optimize the performance for given system parameters in both the absence and presence of channel state information (CSI) error. The proposed scheme provides considerably higher secrecy rate compared to the conventional CB-based PLS schemes, when an eavesdropper exists near to the intended receiver. Furthermore, through simulation and numerical results, we show that the secrecy rate of the proposed scheme can be maximized by adjusting the ratio between the data beamformer and AN injection beamformer components. As a result, the proposed method shows a performance improvement of up to two times compared to the conventional CB-based PLS schemes, in terms of the secrecy rate. Such performance gain increases as the angular location of Eve becomes closer to that of Bob, which corresponds to the most vulnerable situation of the conventional CB-based PLS algorithms.

Multi-level models for data security in networks and in the Internet of things

Data flow control for security is a mature research area in computer security, and its established results can be adapted to the newer area of data security in the Internet of things or the Cloud. This paper takes a fundamental approach to the problem. It shows that, under reflexivity and transitivity assumptions, any network of communicating entities can be seen as a partial order of equivalence classes of entities, which is a simplification and generalization of current theory based on the lattice concept, where lattices are generated by labelling. Networks of communicating entities can be created in many ways, including routing, access control policies (possibly involving labeling), etc. Their intrinsic partial orders are necessary and sufficient for data security, and in any such network entities will have greater or lower secrecy or integrity according to their position in the partial order. It is shown how labeling systems, capable of expressing many types of security requirements, can be constructed to assign entities to their appropriate positions in network partial orders. Established paradigms in data security, such as conflicts, conglomeration, aggregation, are introduced in examples. Then it is shown how entities can be added, removed or relocated in partial orders, as a result of events such as user or administrative action. A label-based method is described to maintain security requirements through such transformations. Efficient algorithms exist to implement these concepts, they are applications of transitive closure algorithms and strongly connected component algorithms.

Jamming-Assisted Legitimate Eavesdropping and Secure Communication in Multicarrier Interference Networks

This article investigates legitimate eavesdropping and secure communication in a multicarrier interference network, where a suspicious link coexists with an unsuspicious link, in the presence of a full-duplex monitor. It is assumed that the unsuspicious users (UUs) are under illegal eavesdropping threat from the suspicious users (SUs), and the monitor can send jamming signals to interfere with the SUs. The UUs are required to cooperate with the monitor for reducing the secrecy outage probability of the UUs to be lower than that without the monitor’s jamming. Under this secrecy outage constraint along with the transmit power constraints, the problem for maximizing the successful eavesdropping probability of the monitor by jointly allocating the transmit powers of the monitor and the UUs is investigated. The problem is solved with the Lagrange duality method by proving the time-sharing property holds, where two algorithms are proposed for obtaining the dual function based on the block coordinate descent method and the successive convex approximation method. Simulation results verify that the proposed algorithms are superior to the noncooperative strategy and the passive eavesdropping strategy, and achieve high successful eavesdropping probability and low secrecy outage probability simultaneously.

Secure Precoding Aided Spatial Modulation via Transmit Antenna Selection

In this paper, two transmit antenna selection schemes are proposed for precoding-aided spatial modulation (PSM) to enhance the secrecy performance with reduced hardware complexity. The first strategy is determined by the channel state information (CSI) of both the legitimate and illegitimate links, called deterministic antenna selection based PSM (DAS-PSM), which selects partial transmit antennas to implement zero-forcing (ZF) precoding for maximizing the secrecy rate. For practical implementation, the low-complexity DAS-PSM criterion is demonstrated. The second strategy resorts to random antenna selection (RAS) with the aid of fast radio-frequency switching. Different from the DAS-PSM, this so-called RAS based PSM (RAS-PSM) dispenses with the CSI of the wiretap channel, which generates the ZF precoding matrix associated with randomly selected transmit antenna combination during each symbol period, creating additional turbulence that solely affects the eavesdropper. To combat the issue of low secrecy rate in the high signal-to-noise ratio regime due to the finite-alphabet inputs, time-varying artificial noise with extra power can be incorporated into both aforementioned strategies, which is exemplified in the RAS-PSM. Finally, the secrecy rates of both proposed schemes are theoretically analyzed and evaluated via Monte Carlo simulations, demonstrating that both proposed schemes with different requirements are capable of enhancing the secrecy performance compared to the conventional PSM.

Cache-Enabled Physical Layer Security for Video Streaming in Backhaul-Limited Cellular Networks

In this paper, we propose a novel wireless caching scheme to enhance the physical layer security of video streaming in cellular networks with limited backhaul capacity. By proactively sharing video data across a subset of base stations (BSs) through both caching and backhaul loading, secure cooperative joint transmission of several BSs can be dynamically enabled in accordance with the cache status, the channel conditions, and the backhaul capacity. Assuming imperfect channel state information (CSI) at the transmitters, we formulate a two-stage non-convex mixed-integer robust optimization problem for minimizing the total transmit power while providing quality of service (QoS) and guaranteeing communication secrecy during video delivery, where the caching and the cooperative transmission policy are optimized in an offline video caching stage and an online video delivery stage, respectively. Although the formulated optimization problem turns out to be NP-hard, low-complexity polynomial-time algorithms, whose solutions are globally optimal under certain conditions, are proposed for cache training and video delivery control. Caching is shown to be beneficial as it reduces the data sharing overhead imposed on the capacity-constrained backhaul links, introduces additional secure degrees of freedom, and enables a power-efficient communication system design. Simulation results confirm that the proposed caching scheme achieves simultaneously a low secrecy outage probability and a high power efficiency. Furthermore, due to the proposed robust optimization, the performance loss caused by imperfect CSI knowledge can be significantly reduced when the cache capacity becomes large.

Secrecy performance of finite-sized cooperative full-duplex relay systems with unreliable backhauls

This paper investigates secrecy performance of finite-sized cooperative full-duplex relay (FDR) systems with unreliable wireless backhaul connections across multiple transmitters under Nakagami- $m$ fading. Closed-form expressions for the secrecy outage probability and probability of nonzero achievable secrecy rate are derived in terms of self-interference (SI), transmitter cooperation, and backhaul reliability. It is shown that transmitter cooperation can effectively enhance the secrecy performance, while the asymptotic limits on the secrecy outage probability and probability of nonzero achievable secrecy rate are exclusively determined by backhaul reliability. With the aid of transmitter cooperation, the burden of SI cancelation can be alleviated for the FDR system in achieving the smallest allowed secrecy outage probability. Compared to that of a half-duplex relay (HDR) system, the FDR system achieves a lower secrecy outage probability with well suppressed SI. The analysis shows that the secrecy outage probability achieved by the FDR system converges to that of the HDR system under perfect backhaul as the target secrecy rate becomes small. The secrecy performance metrics of the considered system are verified by simulations for various backhaul scenarios.

Secrecy and Energy Efficiency in Massive MIMO Aided Heterogeneous C-RAN: A New Look at Interference

In this paper, we investigate the potential benefits of the massive multiple-input multiple-output (MIMO) enabled heterogeneous cloud radio access network (C-RAN) in terms of the secrecy and energy efficiency (EE). In this network, both remote radio heads (RRHs) and massive MIMO macrocell base stations (BSs) are deployed and soft fractional frequency reuse (S-FFR) is adopted to mitigate the inter-tier interference. We first examine the physical layer security by deriving the area ergodic secrecy rate and secrecy outage probability. Our results reveal that the use of massive MIMO and C-RAN can greatly improve the secrecy performance. For C-RAN, a large number of RRHs achieves high area ergodic secrecy rate and low secrecy outage probability, due to its powerful interference management. We find that for massive MIMO aided macrocells, having more antennas and serving more users improves secrecy performance. Then we derive the EE of the heterogeneous C-RAN, illustrating that increasing the number of RRHs significantly enhances the network EE. Furthermore, it is indicated that allocating more radio resources to the RRHs can linearly increase the EE of RRH tier and improve the network EE without affecting the EE of the macrocells.

A graph database framework for covert network analysis: An application to the Islamic State network in Europe

This paper proposes a new framework, based on graph database theory, for encoding complex data on covert networks, mapping their structure, and conducting a sensitivity analysis. The framework is then applied to reconstruct the terrorist network of the 2015–2016 attacks in Paris and Brussels, and related plots in Europe by the Islamic State group. The resulting network was found to be qualitatively different from the ideologically-related Al-Qaeda network, having a lower secrecy and a lower mean degree, under different network-generating assumptions.

Operations in Offshore Financial Centers and Stock Price Crash Risk

Using a large sample of multinational companies that establish affiliates or subsidiaries in offshore financial centers (OFC) but are headquartered in 29 non-OFC countries, we find that OFC operations tend to increase stock price crash risk at the firm level, and that firms operating in OFCs with more profound OFC characteristics have higher crash risk. Moreover, we show that low corporate tax rates and stringent secrecy policies, which are two distinguishing aspects of OFCs, are likely to be the key drivers that increase stock price crash risk. Finally, we find that more conservative accounting information and stronger external monitoring such as analyst coverage and investor protection attenuate the positive relation between OFC operations and crash risk. Our results are robust to a variety of sensitivity checks. JEL Classification: G15, H26, M41, F36

Signal Mapping for Bit-Interleaved Coded Modulation Schemes to Achieve Secure Communications

In this letter, we investigate different signal mappings for bit-interleaved coded modulation (BICM) and their effect on the secrecy information rate of a wire-tap channel exhibiting Rayleigh fading. By focusing on BICM schemes using 64 QAM, 16 QAM and (1, 5, 10) signal constellations, we show that the optimal mapping depends on the range of signal-to-noise ratios (SNRs) we are interested in. We propose a new mapping algorithm, called maximum error event (MEE), to optimize the secrecy rate over a wide range of SNRs. At low SNR, MEE mapping achieves a lower secrecy rate than other well known mappings, but at medium-to-high SNRs MEE mapping achieves a significantly higher secrecy rate over a wide range of SNRs. Simulation results on 16 QAM, 64 QAM and (1, 5, 10) constellations are presented to show the achievable secrecy rates of various mappings for BICM from low to high SNRs.

What Mom and Dad Don’t Know CAN Hurt You: Adolescent Disclosure to and Secrecy From Parents About Type 1 Diabetes

To examine how adolescent disclosure to and secrecy from parents were related to parental knowledge of diabetes management behaviors, and to adolescent adherence, metabolic control, and depressive symptoms. A total of 183 adolescents with type 1 diabetes reported on disclosure to and secrecy from parents regarding diabetes management, adherence behaviors, depressive symptoms, and perceptions of parental knowledge. Mothers and fathers reported on their own knowledge. Adolescent disclosure was associated with all reporters' perceptions of knowledge. Secrecy from both parents moderated the relationship between disclosure and adherence, and secrecy from fathers moderated the relationship between disclosure to fathers and glycosylated hemoglobin level. In all cases, disclosure was associated with better diabetes management only when secrecy was low. Finally, higher secrecy related to greater adolescent depressive symptoms. Disclosure to parents appears to be an important component of how parents get their knowledge about adolescents' diabetes management, but may be most beneficial for diabetes management when it occurs together with low secrecy.

The influence of conservatism and secrecy on the interpretation of verbal probability expressions in the Anglo and Latin cultural areas

We use Gray's [Gray, S.J. (1988). Towards a theory of cultural influence on the development of accounting systems internationally. Abacus, 24 (1), 1–15.] theory of the influence of culture on accounting to develop hypotheses about the effect the interaction of the accounting values of conservatism and secrecy and the context in which probability expressions are used in accounting standards will have on accountants' interpretations of those expressions. Specifically, we expect accountants in a high conservatism country to assign a higher (lower) numerical probability to verbal probability expressions that determine the threshold for the recognition of items that increase (decrease) income than accountants in a low conservatism country. We expect accountants in a high secrecy country to assign higher numerical probabilities to verbal probability expressions that establish the probability threshold for the disclosure of information than accountants in a low secrecy country. We survey professional accountants in Brazil (higher conservatism and higher secrecy) and in the United States (lower conservatism and lower secrecy) to test our hypotheses. We obtain some support for the first conservatism hypothesis related to the recognition of income-increasing items, but no support for the second conservatism hypothesis related to income-decreasing items. We obtain stronger results in support of our hypothesis related to secrecy and disclosure. This study contributes to the literature by investigating the impact of culture on interpretation of verbal probability expressions in the Latin cultural area and by testing Gray's theory, especially the secrecy hypothesis, at the individual-accountant level.

The double-edged sword of secrecy in military weapon development

The Tomahawk missile is the United States Navy's premier land attack cruise missile and has enjoyed significant positive press during both Gulf Wars and in the recent strikes in Afghanistan. Considering the large and versatile inventory of the U.S. military, it is no small achievement for a single to be considered the weapon of choice. In fact, the United States Air Force has its own land attack cruise missile called the Conventional Air-Launched Cruise Missile (CALCM). Both the Tomahawk and the CALCM were conceived and initially developed under the same Department of Defense (DoD) program, the Joint Military Cruise Program Office. These two missiles with nearly identical early development and missions experienced quite different fates. The success of the Navy's Tomahawk, a program with relatively low secrecy when compared to the Air Force's CALCM, should be a lesson to military managers of future weapons procurement programs.