Mohamed Hamdi

Computer and network security risk management: theory, challenges, and countermeasures

The need to secure information systems and networked infrastructures is now commonplace in most enterprises. The use of novel communication technologies has became a crucial factor that can considerably improve or affect productivity. This is essentially due to the importance of the information transmitted across communication networks and stored in servers. As a consequence, strong ties are being built between security and the enterprise business activity. Risk management, which is the discipline that deals with this aspect, integrates a litany of architectures, techniques, and models that are described in this paper. A global view is proposed to the reader through a presentation of the research activity that has been directed towards this field. Copyright

Game-based adaptive security in the Internet of Things for eHealth

The Internet of Things (IoT) is enabling the deployment of distributed applications based on ubiquitous computing and convergent networks. Due to its heterogeneous structure, it introduces new security challenges and requirements. Particularly, the security mechanisms implemented in the IoT should adapt to the dynamic context. This paper proposes a game-based model for adaptive security in the IoT, with an emphasis on eHealth applications. We use the trade-off between security-effectiveness and energy-efficiency to evaluate adaptive security strategies. We also present the results of simulation experiments to assess the performance of the proposed model. We show that our model allows extending the lifetime of the smart things by 47% compared to existing models.

Fault Analysis Attack on an FPGA AES Implementation

Hardware implementation of cryptographic algorithms are widely used to secure wireless networks. They guarantee good security performance at low processing and energy costs. However, unlike traditional implementations, they are vulnerable to side channel attacks. Particularly, fault attacks have proved their efficiency in cracking hardware implementation of some robust symmetric and asymmetric encryption algorithms. In this paper, we develop an FPGA version of the attack proposed by Piret and Quisquater against the AES (Advanced Encryption Standard) algorithm. Through temporal and spatial analyses of the rounds that have been affected by the fault injection process, we adapt the aforementioned attack to our context. The results obtained in this paper can serve to design a more secure FPGA implementation of AES.

Bandwidth-Effective Design of a Satellite-Based Hybrid Wireless Sensor Network for Mobile Target Detection and Tracking

Wireless sensor networks (WSNs) have the potential to assist advanced target tracking applications. The major challenge related to the design of such networks is to cope with the energy and computational limitations that characterize sensor nodes. To address this problem, we propose a hybrid architecture that integrates two sensor categories. The first performs basic detection and tracking functions while the second supports complex tasks such as imaging and broadband communication via a satellite network. Moreover, we develop a technique that allows vision sensors adapting the rate of the exchanged data according to the target activity in the monitored zone. Finally, a tracking approach taking into consideration the error on local sensor position measurements is presented.

Algebraic specification of network security risk management

Existing risk analysis techniques are often hard to handle in real world contexts without the use of appropriate software because of their computational complexity. This makes managers and security analysts use simplified methods to evaluate security investments. However, these methods have been shown to be inefficient in most cases. Therefore, an automated tool for risk management would be of great interest, provided that it allows reasoning on attacks and helps building security decisions. This paper provides an algebraic specification of network security risk management activities. It constitutes a helpful mean to reason about automating the risk assessment process without taking into consideration implementations issues.

A testbed for adaptive security for IoT in eHealth

Wireless Body Area Sensor Networks (WBASNs) are networks of low-power sensing objects that collect and send vital signs of a patient using low-rate communication media. They have been originally created to improve the efficiency of e-health applications and they constitute now an important part of the Internet of Things (IoT) by bringing humans into the IoTs. The ASSET (Adaptive Security for Smart Internet of Things in eHealth) project [1] develops risk-based adaptive security methods and mechanisms for IoT in eHealth. The project requires a real-life testbed to evaluate accurately the adaptive security solutions in realistic simulation and use case scenarios. This paper describes the setup of a testbed for adaptive security for the IoT using current commercial off-the-shelf products and open source software. The particular features of the proposed testbed with regard to those published in the literature are underlined. The paper also discusses the validation of the setup through the study of the impact of antenna orientation on energy consumption. To this purpose, an estimation strategy of the energy consumption using the Holt-Winters prediction method has been developed. This will particularly be useful when studying the feasibility of the adaptive lightweight security solutions that will be part of the ASSET project.

Energy-Efficient Routing in Wireless Sensor Networks Using Probabilistic Strategies

Wireless sensor networks (WSNs) are being used in many applications in order to gather sensitive information and forward it to an analysis center. Since a WSN consists of resource- impoverished sensor nodes, the packet forwarding process should be energy efficient. Therefore, resource limitations should be taken into consideration when designing a WSN infrastructure. This paper proposes a random routing strategy for WSNs. The approach relies on the flooding technique, which has the advantage to possess minimal routing overhead (in the sense that no routing table information is exchanged) and maximal delivery rate. We introduce an enhancement that allows reducing energy consumption and extending network lifetime by randomly forwarding packets at every node. The forward probability is a decreasing function of the number of hops made by the packet. An analytical model is developed in order to illustrate the functionalities of the proposed strategy. Finally, simulations are conducted to assess the performance of the probabilistic routing protocols.

Four dimensional chaotic ciphers for secure image transmission

This paper proposes a chaotic encryption scheme for image data transmission and multimedia communication. To this end, we first extend the definition of the well-known Arnold 2-D chaotic map to the four-dimensional context. We demonstrate that the chaotic behaviour of the Arnold function is enhanced through our extension to four dimensions. Second, we develop a cryptosystem based on the use of chaotic maps and wavelet decomposition. In fact, by involving the wavelet decomposition filters in the encryption process in addition to the pixel positions and the image gray levels, the 4-D chaotic map is defined in a way that it extends the 3-D chaotic map presented in the literature. This allows to adapt the efficiency of the encryption algorithm to the security needs and the available bandwidth through progressive encryption. According to the length of the symmetric key, different resolutions of the image can be obtained at the decryption level.

SAT05-2: Designing a Wireless Sensor Network for Mobile Target Localization and Tracking

Mobile wireless sensor networking is characterized by a set of challenging issues including sensor and target mobility management, sensing continuity, target tracking and sensor density management. We address in this paper various issues related to the localization and tracking of targets. Our approach provides novel schemes for effective location, robustness and sensor density management.

Coverage Assessment and Target Tracking in 3D Domains

Recent advances in integrated electronic devices motivated the use of Wireless Sensor Networks (WSNs) in many applications including domain surveillance and mobile target tracking, where a number of sensors are scattered within a sensitive region to detect the presence of intruders and forward related events to some analysis center(s). Obviously, sensor deployment should guarantee an optimal event detection rate and should reduce coverage holes. Most of the coverage control approaches proposed in the literature deal with two-dimensional zones and do not develop strategies to handle coverage in three-dimensional domains, which is becoming a requirement for many applications including water monitoring, indoor surveillance, and projectile tracking. This paper proposes efficient techniques to detect coverage holes in a 3D domain using a finite set of sensors, repair the holes, and track hostile targets. To this end, we use the concepts of Voronoi tessellation, Vietoris complex, and retract by deformation. We show in particular that, through a set of iterative transformations of the Vietoris complex corresponding to the deployed sensors, the number of coverage holes can be computed with a low complexity. Mobility strategies are also proposed to repair holes by moving appropriately sensors towards the uncovered zones. The tracking objective is to set a non-uniform WSN coverage within the monitored domain to allow detecting the target(s) by the set of sensors. We show, in particular, how the proposed algorithms adapt to cope with obstacles. Simulation experiments are carried out to analyze the efficiency of the proposed models. To our knowledge, repairing and tracking is addressed for the first time in 3D spaces with different sensor coverage schemes.