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 briefly introduced. The survey concludes with observations on potential research directions in this area.

/pdf/principles-of-physical-layer-security-in-multiuser-wireless-3w4jvwpgy4.pdf

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.

/pdf/principles-of-physical-layer-security-in-multiuser-wireless-4usqynlhdb.pdf

Intelligent financial fraud detection

Crowdsourcing information systems are socio-technical systems that provide informational products or services by harnessing the diverse potential of large groups of people via the Web. Interested individuals can contribute to such systems by selecting among a wide range of open tasks. Arguing that current approaches are suboptimal in terms of matching tasks and contributors' individual interests and capabilities, this article advocates the introduction of personalized task recommendation mechanisms. We contribute to a conceptual foundation for the design of such mechanisms by conducting a systematic review of the corresponding academic literature. Based on the insights derived from this analysis, we identify a number of issues for future research. In particular, our findings highlight the need for more significant empirical results through large-scale online experiments, an improved dialog with mainstream recommender systems research, and the integration of various sources of knowledge that exceed the boundaries of individual systems.

Personalized task recommendation in crowdsourcing information systems - Current state of the art

The era of Web 2.0 is witnessing the proliferation of online social media platforms, which develop new business models by leveraging user-generated content. One rapidly growing source of user-generated data is online reviews, which play a very important role in disseminating information, facilitating trust, and promoting commerce in the e-marketplace. In this paper, we develop and compare several text regression models for predicting the helpfulness of online reviews. In addition to using review words as predictors, we examine the influence of reviewer engagement characteristics such as reputation, commitment, and current activity. We employ a reviewer's RFM (Recency, Frequency, Monetary Value) dimensions to characterize his/her overall engagement and investigate if the inclusion of those dimensions helps improve the prediction of online review helpfulness. Empirical findings from text mining experiments conducted using reviews from Yelp and Amazon offer strong support to our thesis. We find that both review text and reviewer engagement characteristics help predict review helpfulness. The hybrid approach of combining the textual features of bag-of-words model and RFM dimensions produces the best prediction results. Furthermore, our approach facilitates the estimation of the helpfulness of new reviews instantly, making it possible for social media platforms to dynamically adjust the presentation of those reviews on their websites.

The influence of reviewer engagement characteristics on online review helpfulness: A text regression model

A fraudulent financial statement involves the intentional furnishing and/or publishing of false information in it and this has become a severe economic and social problem. We consider Data Mining (DM) based financial fraud detection techniques (such as regression, decision tree, neural networks and Bayesian networks) that help identify fraud. The effectiveness of these DM methods (and their limitations) is examined, especially when new schemes of financial statement fraud adapt to the detection techniques. We then explore a self-adaptive framework (based on a response surface model) with domain knowledge to detect financial statement fraud. We conclude by suggesting that, in an era with evolutionary financial frauds, computer assisted automated fraud detection mechanisms will be more effective and efficient with specialized domain knowledge.

Detecting evolutionary financial statement fraud

Radio-Frequency Identification (RFID) tags are gaining widespread popularity throughout the supply chain from raw material acquisition, manufacturing, transportation, warehousing, retailing to the ...

https://link.springer.com/content/pdf/10.1057%2Fejis.2009.41.pdf

Challenges associated with RFID tag implementations in supply chains

In any supply chain, there is a high likelihood for individual objects to change ownership at least once in their lifetime. As RFID tags enter the supply chain, these RFID-tagged objects should ideally be able to seamlessly accommodate ownership transfer issues while also accomplishing their primary intended purpose. Physical ownership transfer does not translate to strict ownership transfer in the presence of RFID tags given the wireless nature of communication with these tags. Moreover, whereas existing protocols implicitly assume a single tag that is owned by a single entity, it is not uncommon to encounter scenarios where tag ownership is shared among multiple entities. A dual of this is the case of an object with multiple tags. We consider ownership transfer scenarios for shared ownership transfer and single object with multiple RFID tags. In the multiple-tagged object case, we consider the possibility where objects gain and lose tags over time. We also present a protocol for simultaneous transfer of ownership of multiple tags between owners. Since ownership transfer without a trusted third party (TTP) is difficult to achieve, we propose a shared ownership sharing protocol and evaluate its properties.

Multi-tag and multi-owner RFID ownership transfer in supply chains

Authentication of RFID tags is commonly achieved through cryptographic means with protocols that encrypt communication between the parties of interest. There is an extensive literature in this area that address various facets associated with authentication. As RFID tags gain more popularity, there is a concomitant increase in frequency with which they (i.e., the tagged object) change ownership. There is, therefore, an urgent need to develop and evaluate protocols that address issues related to ownership transfer of RFID tags. Over the past few years, researchers have proposed several ownership transfer protocols. We consider some of the ownership transfer protocols that were published during the past year and identify present vulnerabilities.

Vulnerabilities in some recently proposed RFID ownership transfer protocols

A majority of extant literature on recommender systems assume the input data as a given to generate recommendations. Both implicit and/or explicit data are used as input in these systems. The existence of various challenges in using such input data including those associated with strategic source manipulations, sparse matrix, state data, among others, are sometimes acknowledged. While such input data are also known to be rife with various forms of bias, to our knowledge no explicit attempt is made to correct or compensate for them in recommender systems. We consider a specific type of bias that is introduced in online product reviews due to the sequence in which these reviews are written. We model several scenarios in this context and study their properties.

/pdf/input-online-review-data-and-related-bias-in-recommender-4mg6i2v6rt.pdf

Gaurav Kapoor

Papers

Detecting evolutionary financial statement fraud

Challenges associated with RFID tag implementations in supply chains

Multi-tag and multi-owner RFID ownership transfer in supply chains

Vulnerabilities in some recently proposed RFID ownership transfer protocols

Input online review data and related bias in recommender systems