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Topology Maintenance Protocols (TMPs) are key for operating Wireless Sensor Networks (WSNs). Their adoption serves a few goals, such as, to save energy, to avoid collisions in communications and to have an adequate number of nodes monitoring the environment-by alternating duty cycles with sleep cycles on the sensor nodes. While effectiveness of TMPs protocols is widely addressed, security is an overlooked feature. Indeed, while different TMPs have been presented in the literature, few of them address the security issues. In particular, only recently a secure TMP protocol that does not require pair-wise node confidentiality has been proposed: Sec-TMP. The aim of Sec-TMP is to enforce event delivery to the Base Station while providing a standard topology maintenance service to the WSN. In this paper, we provide a thorough assessment of our previous preliminary proposal of Sec-TMP, with particular reference to its effectiveness and security. First, we investigate the energy consumption introduced by TMPs protocols. Second, we show that Sec-TMP performs well without any assumption neither on the show-up time of data-collecting node, nor on their mobility model. In particular, we test Sec-TMP against a realistic unpredictable data-collecting mobility scenario, that also brings in new security issues. A thorough security analysis of the proposed solutions to these new issues is also provided. Finally, extensive simulations support the quality of Sec-TMP as for effectiveness and security. Copyright © 2011 John Wiley & Sons, Ltd. Topology Maintenance Protocols are key for operating WSNs, by alternating duty cycles with sleep cycles on the sensor nodes. This paper gives a detailed description and a thorough assessment of Sec-TMP: a secure TMP protocol with the particular aim of enforcing the delivery of events to the Base Station. We investigate Sec-TMP effectiveness and security, also against a realistic unpredictable data-collecting mobility scenario. The results show that Sec-TMP is effective and efficient. The discussion also brings in new security issues. [ABSTRACT FROM AUTHOR]

A new privacy model for Location-Based Services (LBSs) has been recently proposed based on users' footprints-these being a repre-sentation of the amount of time a user spends in a given area. Unfortunately, while the model is claimed to be independent from the specific knowledge of the adversary about users' footprints, we argue that an adversary, that has a more structured knowledge over time, can pose a threat to the privacy guarantees of the model. The major contribution of this paper is to show that time is a relevant dimension that needs to be taken into consideration when investigating LBSs privacy issues. In particular, we show that applying our considerations, user privacy can be violated. We support our claim with analysis and a concrete example. Furthermore, by analyzing a real data set of vehicular traces, we show that the threat is actually present in a real scenario and that its effect on jeopardizing user privacy is relevant. [ABSTRACT FROM AUTHOR]