Antonio Vincenzo Taddeo

Gradual adaptation of security for sensor networks

Wireless sensor networks are composed of nodes with stringent constraints on resources. Some of this devices may have the possibility to recharge batteries (e.g., by means of solar panels); though, a reduced power consumption is anyway a key factor when recharge resources are not available (e.g., during the night for solar panels). In this paper we describe a method for security self-adaptation tailed for wireless sensor networks. This method allows devices to adapt security of applications gradually with the goal of guaranteeing the maximum possible level of security while satisfying power constraints. A case study, implemented on Sun SPOTs, is also presented to show how the method works in a real wireless sensor network.

Coordinated management of hardware and software self-adaptivity

Self-adaptivity is the capability of a system to adapt itself dynamically to achieve its goals. Self-adaptive systems will be widely used in the future both to efficiently use system resources and to ease the management of complex systems. The frameworks for self-adaptivity developed so far usually concentrate either on self-adaptive software or on self-adaptive hardware, but not both. In this paper, we propose a model of self-adaptive systems and we describe how to manage self-adaptivity at all levels (both hardware and software) by means of a decentralized control algorithm. The key advantage of decentralized control is in the simplicity of the local controllers. Simulation results are provided to show the main characteristics of the model and to discuss it.

Run-time selection of security algorithms for networked devices

One of the most important challenges that need to be currently faced in securing resource-constrained embedded systems is optimizing the trade-off between resources used (energy consumption and computational capabilities required) and security requirements for cryptographic algorithms: any adopted security solutions should guarantee an adequate level of protection, yet respecting constraints on computational resources and consumed power. In this paper a generic, efficient, and energy-aware mechanism to determine a correct trade off between security requirements and resources consumed is proposed. The solution proposed relies on Analytic Hierarchy Process (AHP) to define priorities among different requirements and to compare different security solutions. A knapsack problem is formulated to select the most relevant algorithms based on their utility and on available resources.

Characterization of in-tunnel distance measurements for vehicle localization

An increased number of vehicular applications and services requires accurate distance measurements. Due to specific properties of radio waves propagation, it may not be effective to use ranging systems designed for other environments inside tunnels. In this paper we analysed the characteristics of time of flight based ranging for in-tunnel applications. Based on our analysis, we designed a vehicle localization system showing that the time of flight approach is a suitable, accurate and cost effective solution for this purpose. We designed and validated our solution by performing real experiments in a tunnel located in Lugano, Switzerland.

A Protocol for Pervasive Distributed Computing Reliability

The adoption of new hardware and software architectures will make future generations of pervasive devices more flexible and extensible. Networks of computational nodes will be used to compose such systems. In these networks tasks will be delegated dynamically to different nodes (that may be either general purpose or specialized). Thus, a mechanism to verify the reliability of the nodes is required, especially when nodes are allowed to move in different networks. In this context, the reliability of nodes is determined by their ability to execute the tasks assigned to them with the promised performances. This paper proposes a protocol to evaluate the reliability of the different nodes in the network, thus providing a trusting mechanism among nodes which can also manage the soft/hard real-time constrains of task execution. Some simulation results are also shown to help describing the properties of the protocol.

Security and Packets Delivery Trade-Off for WSN

The optimization of resources to be used for securing transmissions in wireless sensor networks while retaining communication quality of service is a challenging task. In this paper, we propose an energy-aware mechanism to determine the most efficient set of packets to be processed according with the resource consumed and the packets delivery requirements.

A Security Service Protocol for MANETs

Mobile Ad-hoc Networks are composed of heterogeneous mobile systems. Securing their communications may be difficult due to differences in the supported algorithms and protocols. In this paper we propose a protocol to negotiate security settings for the communications. This protocol aims at minimizing the power consumption and at providing the highest possible security level associated with the communications.

Dynamic Adaptation of Security and QoS in Energy-Harvesting Sensors Nodes

Pervasive computing applications have, in many cases, hard requirements in terms of security. In particular when deploying a Wireless Sensor Network (WSN), security and privacy exigences must be accommodated with the small computational power and especially with the limited energy of the nodes. In some applications nodes may be equipped with energy harvesting devices, especially solar cells, to keep their small batteries charged. The presence of an harvesting device, while enabling the use of WSN in more application fields, represents an additional challenge in the design phase. Given the stochastic nature of most energy harvesting sources, optimizing system performance requires the capability to evaluate the current system conditions runtime.

Scheduling Small Packets in IPSec Multi-accelerator Based Systems

IPSec is a suite of protocols that adds security to communications at the IP level. Protocols within the IPSec suite make extensive use of cryptographic algorithms. Since these algorithms are computationally very intensive, some hardware acceleration is needed to support high throughput. IPSec accelerator performance may heavily depend on the dimension of the packets to be processed. In fact, when packets are small, the time needed to transfer data and to set up the accelerators may exceed the one to process (e.g. to encrypt) the packets by software. In this paper we present a packet scheduling algorithm that tackles this problem. Packets belonging to the same Security Association are grouped before the transfer to the accelerators. Thus, the transfer and the initialization time have a lower influence on the total processing time of the packets. This algorithm also provides the capability of scheduling grouped packets over multiple cryptographic accelerators. High-level simulations of the scheduling algorithm have been performed and the results for a one-accelerator and for a two-accelerator system are also shown in this paper.

Time of flight error compensation for in-tunnel vehicle localization

Vehicle localization systems rely on measuring distances between a given target and a set of reference points. The accuracy of a localization system strictly depends on the exactness of these measurements. However, the estimation of distances via wireless signals is affected by errors due to factors such as channel noise and multipath propagation. Precise localization is very important for emergency management, especially in tunnels where accidents such as fire typically cause more damage due to difficult evacuation. In this paper we analysed the characteristics of time of flight based ranging in tunnel environment from the error stand point with the aim of designing an error compensation unit. We integrated such a compensation unit within an existing vehicle localization system to improve the localization accuracy. We designed and validated our solution by performing real experiments in a tunnel located in Lugano, Switzerland.