Catálogo de publicaciones - libros

Navigation of mobile wireless sensor networks and fast target acquisition without a map are two challenging problems in search and rescue applications. In this paper, we propose and evaluate a novel Gradient Driven method, called GraDrive. Our approach integrates per-node prediction with global collaborative prediction to estimate the position of a stationary target and to direct mobile nodes towards the target along the shortest path. We demonstrate that a high accuracy in localization can be achieved much faster than other random work models without any assistance from stationary sensor networks. We evaluate our model through a light-intensity matching experiment in MicaZ motes, which indicates that our model works well in a wireless sensor network environment. Through simulation, we demonstrate almost a 40% reduction in the target acquisition time, compared to a random walk model, while obtaining less than 2 unit error in target position estimation.

Vehicular Ad-hoc Networks (VANETs) have emerged as a new network environment for intelligent transportation systems. In this paper, we focus on traffic monitoring (TM) and roadside message transfer (RMT) applications. The TM application (TMA) allows drivers to query traffic conditions at some distance ahead of themselves so that they can make decisions on route changes. The RMT application (RMTA) allows data messages to be delivered between roadside entities e.g. emergency messages, via the moving vehicles. We design a robust data transfer protocol (RDTP), and evaluate its effectiveness on the two applications with various vehicular density and vehicular speed. Our study shows that our protocol achieves comparably accurate speed estimate and higher query success rate with lower control overhead than VITP, an existing protocol designed for TMA. It also achieves higher data throughput and lower delivery latency than another existing approach for RMTA.

It is challenging to support multimedia transmissions over wireless networks, especially, wireless mesh networks, due to some natural resource constraints of wireless networks. In this paper, we investigate in detail some possible improvements on a number of layers to enable the multimedia transmission over wireless networks with QoS support. We implement all our protocols in some test-beds to study their real time performances. We first study a number of improvements of some existing routing protocols to support multimedia transmissions. Some new admission control and rate control mechanisms are studied and their performance gains are verified in our experiments. In our new cross-layer adaptive rate control (CLARC) mechanism, we adaptively change the video encoder’s output bit rate based on the available network bandwidth to improve the quality of the received video. We design and implement a campus test-bed for supporting multimedia traffics in mobile wireless mesh networks. We also design a mobile gateway protocol to connect the MANET to Internet and a wireless LAN management protocol to automatically manage WLAN to provide some QoS.

With the development of ad hoc networks, it is one of the most important problems to protect the security of information flows between the nodes. The paper applies the technique of trusted computing to designing the Trust Extended Dynamic (TED) security model. TED model protects the security of information flows between the nodes built on trusted platforms. The security model is based on BLP and Biba models. Due to introducing the concept of reliability and the functions for the trustworthy state measurements, the trustworthiness of subjects and some objects is monitored, and the accessing ranges of subjects are adjusted at runtime. Through these means, the ability of TED security model to resist running attacks is enhanced. The formal description of TED model is specified in detail, and its security properties are described. The paper also introduces the application of the model in the Trusted Web Server (TWS).

In 2006, Manik et al. proposed a novel remote user authentication scheme using bilinear pairings. Chou et al. identified a weakness in Manik et al.’s scheme and improved the scheme. And besides, Thulasi et al. pointed that both Manik et al.’s and Chou et al.’s schemes are vulnerable to forgery attacks and replay attacks. In this paper, we analyze the previous schemes based on a timestamp and provide further comments and an improved scheme using a nonce. Our scheme also provides mutual authentication between a user and a remote server while the previous schemes only provided unilateral authentication.

In this paper, we propose a new architecture based on an efficient trust model and clustering algorithm in order to distribute a certification authority (CA) for ensuring the distribution of certificates in each cluster. We use the combination of fully self-organized security for trust model like PGP adapted to ad-hoc technology and the clustering algorithm which is based on the use of trust and mobility metric, in order to select the clusterhead and to establish PKI in each cluster for authentication and exchange of data. Furthermore, we present new approach Dynamic Demilitarized Zone (DDMZ) to protect CA in each cluster. The principle idea of DDMZ consists to select the dispensable nodes, also called registration authorities; these nodes must be confident and located at one-hope from the CA. Their roles are to receive, filter and treat the requests from any unknown node to CA. With this approach, we can avoid the single point of failure in each cluster. This architecture can be easily extended to other hierarchical routing protocols. Simulation results confirm that our architecture is scalable and secure.

In this paper, we demonstrate a new class of protocol compliant exploits that initiates at the MAC layer but targets ad hoc on-demand routing mechanisms. A misbehaved node implementing this type of attacks completely follows the specifications of IEEE802.11 standard and the existing on-demand routing protocols. However, it can cause routing shortcut attacks or detour attacks. We detail the exploits against two on-demand routing protocols: AODV and DSR. We evaluate the impact of such attacks on the network performance and propose PSD () to mitigate their impacts.

The biggest challenge for current RFID technology is to provide the necessary benefits while avoiding any threats to the privacy of its users. Although many solutions to this problem have been proposed, almost as soon as they have been introduced, methods have been found to circumvent system security and make the user vulnerable. We are proposing an advanced mutual-authentication protocol between a tag and the back-end database server for a RFID system to ensure system security integrity. The three main areas of security violations in RFID systems are forgery of the tags, unwanted tracking of the tags, and unauthorized access to a tag’s memory. Our proposed system protects against these three areas of security violations. Our protocol provides reader authentication to a tag, exhibits forgery resistance against a simple copy, and prevents the counterfeiting of RFID tags. Our advanced mutual-authentication protocol uses an AES algorithm as its cryptograph primitive. Since our AES algorithm has a relatively low cost, is fast, and only requires simple hardware, our proposed approach is feasible for use in RFID systems. In addition, the relatively low computational cost of our proposed algorithm compared to those currently used to implement similar levels of system security makes our proposed system especially suitable for RFID systems that have a large number of tags.

Traditionally the anonymity of an entity of interest can be achieved by hiding it among a group of other entities with similar characteristics, i.e., an anonymity set. In mobile ad hoc networks, generating and maintaining such an anonymity set for any ad hoc node are challenging because of the node mobility and consequently of the dynamic network topology. In this paper, we address the problem of the destination anonymity. We propose protocols that use fuzzy destination position to generate a geographic area called . A packet for a destination is delivered to all the nodes in the AZ, which, consequently, make up the anonymity set. The size of the anonymity set may decrease because nodes are mobile, yet the corresponding management on anonymity set is simple. We design techniques to further improve node anonymity. We use extensive simulation to study the node anonymity and routing performance, and to determine the parameters that most impact the anonymity level that can be achieved by our protocol.

In mobile Ad Hoc networks, the existence and availability of trusted authorities is severely limited by intrinsic network features, and problems such as “service availability” have become a crucial issue. A proxy signature scheme allows an entity to delegate his/her signing capability to another entity in such a way that the latter can sign messages on behalf of the former when the former is not available. This is an important primitive to ensure the service availability issue. Proxy signatures have found numerous practical applications such as distributed systems, mobile agent applications, etc. However, the security of the known proxy signature schemes is proven in the random oracle which does not imply security in the real world. In this paper, we propose the proxy signature schemes random oracle. The unforgeability of our scheme is based on the hardness of the well known Computational Diffie Hellman (CDH) problem.