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Democratic societies are built around the principle of free and fair elections, and that each citizen’s vote should count equally. National elections can be regarded as large-scale social experiments, where people are grouped into usually large numbers of electoral districts and vote according to their preferences. The large number of samples implies statistical consequences for the polling results, which can be used to identify election irregularities. Using a suitable data representation, we find that vote distributions of elections with alleged fraud show a kurtosis substantially exceeding the kurtosis of normal elections, depending on the level of data aggregation. As an example, we show that reported irregularities in recent Russian elections are, indeed, well-explained by systematic ballot stuffing. We develop a parametric model quantifying the extent to which fraudulent mechanisms are present. We formulate a parametric test detecting these statistical properties in election results. Remarkably, this technique produces robust outcomes with respect to the resolution of the data and therefore, allows for cross-country comparisons.

With the innovation of embedded devices, the concept of smart marketplace came into existence. A smart marketplace is a platform on which participants can trade multiple resources, such as water, energy, bandwidth. Trust is an important factor in the trading platform, as the participants would prefer to trade with those peers who have a high trust rating. Most of the existing trust management models for smart marketplace only provide a single aggregated trust score for a participant. However, they lack the mechanism to gauge the level of commitment shown by a participant while trading a particular resource. This work aims to provide a fine-grained trust score for a participant with respect to each resource that it trades. Several parameters, such as resource availability, success rate, and turnaround time are used to gauge the participant’s level of commitment, specific to the resource being traded. Moreover, the effectiveness of the proposed model is validated through security analysis against ballot-stuffing and bad-mouthing attacks, along with simulationbased analysis and a comparison in terms of accuracy, false positive, false negative, computational cost and latency. The results indicate that the proposed trust model has 7% better accuracy, 30.13% lower computational cost and 31.74% less latency compared to the existing benchmark model.

In this paper, we introduce the first application of the belief propagation algorithm in the design and evaluation of trust and reputation management systems. We approach the reputation management problem as an inference problem and describe it as computing marginal likelihood distributions from complicated global functions of many variables. However, we observe that computing the marginal probability functions is computationally prohibitive for large-scale reputation systems. Therefore, we propose to utilize the belief propagation algorithm to efficiently (in linear complexity) compute these marginal probability distributions; resulting a fully iterative probabilistic and belief propagation-based approach (referred to as BP-ITRM). BP-ITRM models the reputation system on a factor graph. By using a factor graph, we obtain a qualitative representation of how the consumers (buyers) and service providers (sellers) are related on a graphical structure. Further, by using such a factor graph, the global functions factor into products of simpler local functions, each of which depends on a subset of the variables. Then, we compute the marginal probability distribution functions of the variables representing the reputation values (of the service providers) by message passing between nodes in the graph. We show that BP-ITRM is reliable in filtering out malicious/unreliable reports. We provide a detailed evaluation of BP-ITRM via analysis and computer simulations. We prove that BP-ITRM iteratively reduces the error in the reputation values of service providers due to the malicious raters with a high probability. Further, we observe that this probability drops suddenly if a particular fraction of malicious raters is exceeded, which introduces a threshold property to the scheme. Furthermore, comparison of BP-ITRM with some well-known and commonly used reputation management techniques (e.g., Averaging Scheme, Bayesian Approach, and Cluster Filtering) indicates the superiority of the proposed scheme in terms of robustness against attacks (e.g., ballot stuffing, bad mouthing). Finally, BP-ITRM introduces a linear complexity in the number of service providers and consumers, far exceeding the efficiency of other schemes.

Trust recommendations, having a pivotal role in computation of trust and hence confidence in peer to peer (P2P) environment, if hampered, may entail in colossal attacks from dishonest recommenders such as bad mouthing, ballot stuffing, random opinion etc. Therefore, mitigation of dishonest trust recommendations is stipulated as a challenging research issue in P2P systems (esp in Mobile Ad Hoc Networks). In order to cater these challenges associated with dishonest trust recommendations, a technique named \"intelligently Selection of Trust Recommendations based on Dissimilarity factor (iSTRD)\" has been devised for Mobile Ad Hoc Networks. iSTRD exploits personal experience of an \"evaluating node\" in conjunction with majority vote of the recommenders. It successfully removes the recommendations of \"low trustworthy recommenders\" as well as dishonest recommendations of \"highly trustworthy recommenders\". Efficacy of the proposed approach is evident from enhanced accuracy of \"recognition rate\", \"false rejection\" and \"false acceptance\". Moreover, experiential results depict that iSTRD has unprecedented performance compared to contemporary techniques in presence of attacks asserted.

Scientists analyzing data from recent international contests, including the questionable 2011 parliamentary elections in Russia, have proposed a new mathematical measure to discern fraudulent elections from fair ones. Graphing the relationship between turnout and votes for the winner revealed unusual peaks in the data for the elections in Russia--a signature of funny business, the scientists contend. Moreover, ballot stuffing best explains the data, says study coauthor Peter Klimek.