Reputation systems and secure communication in vehicular networks

A thorough review of the state of the art will reveal that most VANET applications rely on Public Key Infrastructure (PKI), which uses user certificates managed by a Certification Authority (CA) to handle security. By doing so, they constrain the ad-hoc nature of the VANET imposing a frequent connection to the CA to retrieve the Certificate Revocation List (CRL) and requiring some degree of roadside infrastructure to achieve that connection. Other solutions propose the usage of group signatures where users organize in groups and elect a group manager. The group manager will need to ensure that group members do not misbehave, i.e., do not spread false information, and if they do punish them, evict them from the group and report them to the CA; thus suffering from the same CRL retrieval problem. In this thesis we present a fourfold contribution to improve security in VANETs. First and foremost, Chains of Trust describes a reputation system where users disseminate Points of Interest (POIs) information over the network while their privacy remains protected. It uses asymmetric cryptography and users are responsible for the generation of their own pair of public and private keys. There is no central entity which stores the information users input into the system; instead, that information is kept distributed among the vehicles that make up the network. On top of that, this system requires no roadside infrastructure. Precisely, our main objective with Chains of Trust was to show that just by relying on people¿s driving habits and the sporadic nature of their encounters with other drivers a successful reputation system could be built. The second contribution of this thesis is the application simulator poiSim. Many¿s the time a new VANET application is presented and its authors back their findings using simulation results from renowned networks simulators like ns-2. The major issue with network simulators is that they were not designed with that purpose in mind and handling simulations with hundreds of nodes requires a massive processing power. As a result, authors run small simulations (between 50 and 100 nodes) with vehicles that move randomly in a squared area instead of using real maps, which rend unrealistic results. We show that by building tailored application simulators we can obtain more realistic results. The application simulator poiSim processes a realistic mobility trace produced by a Multi-agent Microscopic Traffic Simulator developed at ETH Zurich, which accurately describes the mobility patterns of 259,977 vehicles over regional maps of Switzerland for 24 hours. This simulation runs on a desktop PC and lasts approximately 120 minutes. In our third contribution we took Chains of Trust one step further in the protection of user privacy to develop Anonymous Chains of Trust. In this system users can temporarily exchange their identity with other users they trust, thus making it impossible for an attacker to know in all certainty who input a particular piece of information into the system. To the best of our knowledge, this is the first time this technique has been used in a reputation system. Finally, in our last contribution we explore a different form of communication for VANETs. The vast majority of VANET applications rely on the IEEE 802.11p/Wireless Access in Vehicular Environments (WAVE) standard or some other form of radio communication. This poses a security risk if we consider how vulnerable radio transmission is to intentional jamming and natural interferences: an attacker could easily block all radio communication in a certain area if his transmitter is powerful enough. Visual Light Communication (VLC), on the other hand, is resilient to jamming over a wide area because it relies on visible light to transmit information and ,unlike WAVE, it has no scalability problems. In this thesis we show that VLC is a secure and valuable form of communication in VANETs

VEACON: A Vehicular Accident Ontology designed to improve safety on the roads

[EN] Vehicles are nowadays provided with a variety of new sensors capable of gathering information about themselves and from their surroundings. In a near future, these vehicles will also be capable of sharing all the harvested information, with the surrounding environment and among nearby vehicles over smart wireless links. They will also be able to connect with emergency services in case of accidents. Hence, distributed applications based on Vehicular Networks (VNs) will need to agree on a `common understanding¿ of context for interoperability, and, therefore, it is necessary to create a standard structure which enables data interoperability among all the different entities involved in transportation systems. In this paper, we focus on traffic safety applications; specifically, we present the VEhicular ACcident ONtology (VEACON) designed to improve traffic safety. Our ontology combines the information collected when an accident occurs, and the data available in the General Estimates System (GES) accidents database. We assess the reliability of our proposal using both realistic crash tests, held in the facilities of Applus+ IDIADA in Tarragona, Spain, and Vehicular Network simulations, based on the ns-2 simulation tool. Experimental results highlight that both nearby vehicles and infrastructure elements (RSUs) are correctly notified about an accident in just a few seconds, increasing the emergency services notification effectiveness. (c) 2012 Elsevier Ltd. All rights reserved.This work was partially supported by the Ministerio de Ciencia e Innovacion, Spain, under Grant TIN2011-27543-C03-01.Barrachina, J.; Garrido, P.; Fogue, M.; Martínez, FJ.; Cano Escribá, JC.; Tavares De Araujo Cesariny Calafate, CM.; Manzoni, P. (2012). VEACON: A Vehicular Accident Ontology designed to improve safety on the roads. Journal of Network and Computer Applications. 35(6):1891-1900. https://doi.org/10.1016/j.jnca.2012.07.013S1891190035

Multimodal speaker identification

This Master Thesis (MT) describes different techniques for speaker identification. Our goal is two-fold: first to build and curate an image and audio dataset and second to use it to create a speaker recognition system

Damage survivability of 'open' ferries with water on deck and proposal of criteria MCA project 425; summary report

Document no. C3202.SRAvailable from British Library Document Supply Centre-DSC:7755.620(425) / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo

Chains of trust in vehicular networks: a secure points of interest dissemination strategy

This article describes a scheme which to the best of our knowledge is the first one to use user signatures to share information about Points of Interest in Vehicular Ad hoc Networks. In this scheme, users rate restaurants, hotels, etc. and sign those rates with their private key. Then, they broadcast that information and other vehicles store it for future use. When another user needs a Point of Interest recommendation he queries the system for the other users stored reviews and after he visits that Points of Interest for himself, he evaluates it and his level of trust in the reviewers with rates similar to his own increases. In the end, a user will be able to request to his vehicle information on a certain Point of Interest category and itwill respond with the recommendations made by other users, prioritizing the ones in the user’s Web of Trust.poi-Sim is the tool designed to simulate this scheme. It processes a 24 h mobility trace produced by a Multi-Agent Traffic Simulator, which realistically simulates public and private traffic over regional maps of Switzerland. The result is a Chains of Trust simulation with over 260,000 nodes, which shows that the proposed scheme performs satisfactorily in a realistic scenario