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Many networks are dynamic in that their topology changes rapidly--on the same time scale as the communications of interest between network nodes. Examples are the human contact networks involved in the transmission of disease, ad hoc radio networks between moving vehicles, and the transactions between principals in a market. While we have good models of(More)
Many research efforts for image encryption schemes have elaborated for designing nonlinear functions since security of these schemes closely depends on inherent characteristics of non-linear functions. It is commonly believed that a chaotic map can be used as a good candidate of a nonlinear component for image encryption schemes. We propose a new image(More)
Nowadays, the use of social media such as Twitter is necessary to monitor trends of people on political issues. As a case study, we collected the main stream of Twitter related to the 2010 UK general election during the associated period. We analyse the characteristics of the three main parties in the election. Also, we propose a simple and practical(More)
A number of web service firms have started to authenticate users via their social knowledge, such as whether they can identify friends from photos. We investigate attacks on such schemes. First, attackers often know a lot about their targets; most people seek to keep sensitive information private from others in their social circle. Against close enemies ,(More)
Instant messaging (IM) is increasingly popular among not only Internet but also smartphone users. In this paper, we analyze the security issue of an IM application, KakaoTalk, which is the most widely used in South Korea, with a focus on automated friends registration based on contacts sync. We demonstrate that there are multiple ways of collecting victims'(More)
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may(More)
Most of the existing phishing detection techniques are weak against domain name system (DNS)-poisoning-based phishing attacks. Proposed is a highly effective method for detecting such attacks: the network performance characteristics of websites are used for classification. To demonstrate how useful the approach is, the performance of four classification(More)
In modern politics, parties and individual candidates must have an online presence and usually have dedicated social media coordinators. In this context, we study the usefulness of analysing Twitter messages to identify both the characteristics of political parties and the political leaning of users. As a case study, we collected the main stream of Twitter(More)
—The problem of maximizing information diffusion through a network is a topic of considerable recent interest. A conventional problem is to select a set of any arbitrary k nodes as the initial influenced nodes so that they can effectively disseminate the information to the rest of the network. However, this model is usually unrealistic in online social(More)