Angelica Lo Duca

Towards a reputation-based routing protocol to contrast blackholes in a delay tolerant network

A Delay Tolerant Network (DTN) relies on the implicit assumption that nodes cooperate towards message forwarding. However, this assumption cannot be satisfied when there are malicious nodes acting as blackholes and voluntarily attracting and dropping messages.In this paper we propose a reputation-based protocol for contrasting blackholes. Every node locally maintains the reputation of forwarding nodes it comes in touch with and, then, upon selecting the next forwarding node, the node chooses among those having the highest reputation. The proposed reputation protocol is composed of three basic mechanisms-acknowledgments, node lists, and aging-that make communication efficient and capable of adapting to the changing operating conditions of a DTN.The protocol has been used to extend CAR 1]. The resulting protocol RCAR (reputation-based CAR) has been compared with T-ProPHET 2], a state-of-the-art reputation-based DTN routing protocol, from several standpoints. As it turns out, RCAR is more effective than T-ProPHET and outperforms it in most cases.

Secure cooperation of autonomous mobile sensors using an underwater acoustic network.

Methodologies and algorithms are presented for the secure cooperation of a team of autonomous mobile underwater sensors, connected through an acoustic communication network, within surveillance and patrolling applications. In particular, the work proposes a cooperative algorithm in which the mobile underwater sensors (installed on Autonomous Underwater Vehicles—AUVs) respond to simple local rules based on the available information to perform the mission and maintain the communication link with the network (behavioral approach). The algorithm is intrinsically robust: with loss of communication among the vehicles the coverage performance (i.e., the mission goal) is degraded but not lost. The ensuing form of graceful degradation provides also a reactive measure against Denial of Service. The cooperative algorithm relies on the fact that the available information from the other sensors, though not necessarily complete, is trustworthy. To ensure trustworthiness, a security suite has been designed, specifically oriented to the underwater scenario, and in particular with the goal of reducing the communication overhead introduced by security in terms of number and size of messages. The paper gives implementation details on the integration between the security suite and the cooperative algorithm and provides statistics on the performance of the system as collected during the UAN project sea trial held in Trondheim, Norway, in May 2011.

A reputation-based approach to tolerate misbehaving carriers in Delay Tolerant Networks

Delay Tolerant Network (DTN) is a network paradigm used to deliver messages when network connectivity is not guaranteed. In a DTN, communication is made possible by carriers, mobile nodes that physically carry messages from a network partition to another. Selecting carriers that provide the best delivery probability is a crucial issue. However, if carriers misbehave, the integrity and availability of a DTN is endangered. In this paper we present a decentralised reputation-based system aimed at tolerating misbehaving carriers. A prototype of the system has been integrated into Context Aware Routing (CAR) [1]. Simulations show that the resulting system RCAR provides a greater delivery probability than CAR and Epidemic Routing [2] without increasing the average delivery delay.

A Secure Communication Suite for Underwater Acoustic Sensor Networks

In this paper we describe a security suite for Underwater Acoustic Sensor Networks comprising both fixed and mobile nodes. The security suite is composed of a secure routing protocol and a set of cryptographic primitives aimed at protecting the confidentiality and the integrity of underwater communication while taking into account the unique characteristics and constraints of the acoustic channel. By means of experiments and simulations based on real data, we show that the suite is suitable for an underwater networking environment as it introduces limited, and sometimes negligible, communication and power consumption overhead.

Mobile Underwater Sensor Networks for Protection and Security: Field Experience at the UAN11 Experiment

The EU-funded project UAN (Underwater Acoustic Network) was aimed at conceiving, developing, and testing at sea an innovative and operational concept for integrating underwater and above-water sensors in a unique communication system to protect offshore and coastline critical infrastructures. This work gives details on the underwater part of the project. It introduces a set of original security features and gives details on the integration of autonomous underwater vehicles (AUVs) as mobile nodes of the network and as surveillance assets, acoustically controlled by the command and control center to respond against intrusions. Field results are given of the final UAN project sea trial, UAN11, held in May 2011 in Norway. During the experimental activities, a UAN composed of four fixed nodes, two AUVs, and one mobile node mounted on the supporting research vessel was operated continuously and integrated into a global protection system. In this article, the communication performance of the network is reported in terms of round-trip time, packet loss, and average delivery ratio. The major results of the experiment can be thus summarized: the implemented network structure wassuccessfulincontinuouslyoperatingoverfivedayswithnodesseamlesslyenteringandexitingthenetwork; the performance of the network varied greatly with fluctuations in the acoustic channel; the addition of security features induced a minor degradation in network performance with respect to channel variation; the AUVs were successfully controlled from a remote station through acoustic signals routed by the network. C

A cryptographic suite for underwater cooperative applications

An underwater acoustic scenario raises many problems in terms of security because of the limited bandwidth provided by the underwater medium. In this paper we face with the problem of secure cooperation among underwater acoustic vehicles. We propose a cryptographic suite able to reduce at the minimum the message overhead added by security. The cryptographic suite provides vehicles authentication, confidentiality and integrity of messages and key management. A prototype has been implemented and preliminary performance evaluation tests are shown.

SeFLOOD: A secure network discovery protocol for Underwater Acoustic Networks

An Underwater Acoustic Network (UAN) raises many issues in terms of security. In this paper we focus on attacks performed during the network discovery phase. At the state of art, all underwater discovery protocols do not provide message authenticity so they are exposed to spoofing-based attacks against network integrity and availability. In this paper, we focus on FLOOD [1], a network discovery protocol for UANs and we extend it in order to provide protection against network authenticity and integrity attacks. In particular we show that certain attacks against integrity and leading to Denial of Service are avoided.

Correlating Languages and Sentiment Analysis on the Basis of Text-based Reviews

Customer experiences, in the shape of online reviews, influence other customers and in general, contribute to build a perception of a destination. This work presents the conclusions of a survey to gather user text-based reviews about several categories of destination-related information (accommodation, restaurants, attractions and Points of Interest) from three well-known social media sources (Facebook, FourSquare and GooglePlaces) about eight worldwide destinations with a high overnight rate. Several hypotheses about the correlation between the language and sentiment features of the reviews have been validated over a large dataset of reviews. For example, the analysis detected that the highest number of reviews in a destination is written in the same official language spoken in that place. Furthermore, Dutch speaking people are more positive when writing a review. Finally, English, Italian and Spanish speakers seem to prefer FourSquare while German and French people are quite evenly distributed among FourSquare and GooglePlaces.

A K-nearest neighbor classifier for ship route prediction

Over the last years the number of AIS messages generated by ships to signal their position has been increasing thus permitting decision support systems to build new strategies based on the elaboration of such data. In this paper we propose an algorithm based on a K-Nearest Neighbor classifier to predict ships routes. The algorithm was tested on real data extracted from AIS messages collected around Malta. Experiments show that our algorithm reaches a precision of 0.794, a recall of 0.785 and an accuracy of 0.931.

SocialTrends: A Web Application for Monitoring and Visualizing Users in Social Media

Nowadays social media trends are becoming very important to describe the variation of popularity, activity and influence of an entity. In this paper we define an abstract model which can be used on different social media to compare metrics with the same meaning. In particular we describe three classes of metrics: popularity, activity and influence. We also present SocialTrends, a web application (http://www.social-trends.it/) which collects, elaborates and visualizes social media data. Finally, we describe one experiment we have done to test SocialTrends.