VANET Connectivity Analysis

Vehicular Ad Hoc Networks (VANETs) are a peculiar subclass of mobile ad hoc networks that raise a number of technical challenges, notably from the point of view of their mobility models. In this paper, we provide a thorough analysis of the connectivity of such networks by leveraging on well-known results of percolation theory. By means of simulations, we study the influence of a number of parameters, including vehicle density, proportion of equipped vehicles, and radio communication range. We also study the influence of traffic lights and roadside units. Our results provide insights on the behavior of connectivity. We believe this paper to be a valuable framework to assess the feasibility and performance of future applications relying on vehicular connectivity in urban scenarios

A programmable architecture for the provision of hybrid services

The success of new service provision platforms will largely depend on their ability to blend with existing technologies. The advent of Internet telephony, although impressive, is unlikely to make telephone customers suddenly turn in favor of computers. Rather, customers display increasing interest in services that span multiple networks (especially Internet Protocol-based networks and the telephone and cellular networks) and open new vistas. We refer to these services as hybrid services and propose an architecture for their provision. This architecture allows for programming the service platform elements (i.e., network nodes, gateways, control servers, and terminals) in order to include new service logics. We identify components that can be assembled to build these logics by considering a service as a composition of features such as address translation, security, call control, connectivity, charging and user interaction. Generic service components are derived from the modeling of these features. We assure that our proposal can be implemented even in existing systems in return for slight changes: These systems are required to generate an event when a special service is encountered. The treatment of this event is handled by an object at a Java Service Layer. Java has been chosen for its platform-neutrality feature and its embedded security mechanisms. Using our architecture, we design a hybrid closed user group service

A Charging and Rewarding Scheme for Packet Forwarding

In multi-hop cellular networks, data packets have to be relayed hop by hop from a given mobile station to a base station and vice-versa. This means that the mobile stations must accept to forward information for the benefit of other stations. In this paper, we propose an incentive mechanism that is based on a charging/rewarding scheme and that makes collaboration rational for selfish nodes. We base our solution on symmetric cryptography to cope with the limited resources of the mobile stations. We provide a set of protocols and study their robustness with respect to various attacks. By leveraging on the relative stability of the routes, our solution leads to a very moderate overhead

Node Cooperation in Hybrid Ad hoc Networks

A hybrid ad hoc network is a structure-based network that is extended using multi-hop communications. Indeed, in this kind of network, the existence of a communication link between the mobile station and the base station is not required: A mobile station that has no direct connection with a base station can use other mobile stations as relays. Compared with conventional (single-hop) structure-based networks, this new generation can lead to a better use of the available spectrum and to a reduction of infrastructure costs. However, these benefits would vanish if the mobile nodes did not properly cooperate and forward packets for other nodes. In this paper, we propose a charging and rewarding scheme to encourage the most fundamental operation, namely packet forwarding. We use ``MAC layering" to reduce the space overhead in the packets and a stream cipher encryption mechanism to provide ``implicit authentication" of the nodes involved in the communication. We analyze the robustness of our protocols against rational and malicious attacks. We show that - using our solution - collaboration is rational for selfish nodes. We also show that our protocols thwart rational attacks and detect malicious attacks

Secure Vehicular Communication Systems: Implementation, Performance, and Research Challenges

Vehicular Communication (VC) systems are on the verge of practical deployment. Nonetheless, their security and privacy protection is one of the problems that have been addressed only recently. In order to show the feasibility of secure VC, certain implementations are required. In [1] we discuss the design of a VC security system that has emerged as a result of the European SeVeCom project. In this second paper, we discuss various issues related to the implementation and deployment aspects of secure VC systems. Moreover, we provide an outlook on open security research issues that will arise as VC systems develop from today's simple prototypes to full-fledged systems

SmarPer: Context-Aware and Automatic Runtime-Permissions for Mobile Devices

Permission systems are the main defense that mobile platforms, such as Android and iOS, offer to users to protect their private data from prying apps. However, due to the tension between usability and control, such systems have several limitations that often force users to overshare sensitive data. In this work, we address some of these limitations with SmarPer, an advanced permission mechanism for Android. First, to address the rigidity of current permission systems and their poor matching of users' privacy preferences, SmarPer relies on contextual information and machine learning to predict permission decisions at runtime. Using our SmarPer implementation, we collected 8,521 runtime permission decisions from 41 participants in real conditions. Note that the goal of SmarPer is to mimic the users decisions, not to make privacy-preserving decisions per se. With this unique data set, we show that tting an efcient Bayesian linear regression model results in a mean correct classication rate of 80% (3%). This represents a mean relative improvement of 50% over a user-dened static permission policy, i.e., the model used in current permission systems. Second, SmarPer also focuses on the suboptimal trade-off between privacy and utility; instead of only “allow” or “deny” decisions, SmarPer also offers an “obfuscate” option where users can still obtain utility by revealing partial information to apps. We implemented obfuscation techniques in SmarPer for different data types and evaluated them during our data collection campaign. Our results show that 73% of the participants found obfuscation useful and it accounted for almost a third of the total number of decisions. In short, we are the first to show, using a large dataset of real in situ permission decisions, that it is possible to learn users’ unique decision patterns at runtime using contextual information while supporting data obfuscation; this an important step towards automating the management of permissions in smartphones

The (Co-)Location Sharing Game: Benefits and Privacy Implications of (Co)-Location Sharing with Interdependences

Most popular location-based social networks, such as Facebook and Foursquare, let their (mobile) users post location and co-location (involving other users) information. Such posts bring social benefits to the users who post them but also to their friends who view them. Yet, they also represent a severe threat to the users' privacy, as co-location information introduces interdependences between users. We propose the first game-theoretic framework for analyzing the strategic behaviors, in terms of information sharing, of users of OSNs. To design parametric utility functions that are representative of the users' actual preferences, we also conduct a survey of 250 Facebook users and use conjoint analysis to quantify the users' benefits of sharing vs. viewing (co)-location information and their preference for privacy vs. benefits. Our survey findings expose the fact that, among the users, there is a large variation, in terms of these preferences. We extensively evaluate our framework through data-driven numerical simulations. We study how users' individual preferences influence each other's decisions, we identify several factors that significantly affect these decisions (among which, the mobility data of the users), and we determine situations where dangerous patterns can emerge (e.g., a vicious circle of sharing, or an incentive to over-share)--even when the users share similar preferences

The Terminodes Project: Towards Mobile Ad-Hoc WANs

The Terminode project follows a system approach to investigate wide area, large, totally wireless networks that we call mobile ad-hoc wide area networks. A network of terminodes is an autonomous, self-operated, wireless multimedia network, independent of any infrastructure. In this paper we present the main challenges and certain initial technical directions

Privacy threats and practical solutions for genetic risk tests

Recently, several solutions have been proposed to address the complex challenge of protecting individuals' genetic data during personalized medicine tests. In this short paper, we analyze different privacy threats and propose simple countermeasures for the generic architecture mainly used in the literature. In particular, we present and evaluate a new practical solution against a critical attack of a malicious medical center trying to actively infer raw genetic information of patients. © 2015 IEEE