Panayiotis Kotzanikolaou

Solving coverage problems in wireless sensor networks using cover sets

To achieve power efficient monitoring of targets by sensor networks, various coverage algorithms have been proposed. These algorithms divide the sensor nodes into cover sets, where each cover set is capable of monitoring all targets. Generating the maximum number of cover sets has been proven to be an NP-complete problem and, thus, algorithms producing sub-optimal solutions have been proposed. In this paper we present a novel and efficient coverage algorithm, that can produce both disjoint cover sets, i.e. cover sets with no common sensor nodes, as well as non-disjoint cover sets. While searching for the best sensor to include in a cover set, our algorithm uses a cost function that takes into account the monitoring capabilities of a sensor, its association with poorly monitored targets, but also the sensors remaining battery life. Through simulations, we show that the proposed algorithm outperforms similar heuristic algorithms found in the literature, producing collections of cover sets of optimal (or near-optimal) size. The increased availability offered by these cover sets along with the short execution time of the proposed algorithm make it desirable for a wide range of node deployment environments.

Secure Transactions with Mobile Agents in Hostile Environments

A major problem of mobile agents is their apparent inability to authenticate transactions in hostile environments. In this paper, we consider a framework for the prevention of agent tampering without compromising the mobility or autonomy of the agent. Our approach uses encrypted functions. We present an RSA implementation which answers affirmatively the open problem on undetachable signatures of Sander and Tschudin.

SecMR – a secure multipath routing protocol for ad hoc networks

Abstract Multipath routing in ad hoc networks increases the resiliency against security attacks of collaborating malicious nodes, by maximizing the number of nodes that an adversary must compromise in order to take control of the communication. In this paper, we identify several attacks that render multipath routing protocols vulnerable to collaborating malicious nodes. We propose an on-demand multipath routing protocol, the secure multipath routing protocol (SecMR), and we analyze its security properties. Finally, through simulations, we evaluate the performance of the SecMR protocol in comparison with existing secure multipath routing protocols.

Preventing impersonation attacks in MANET with multi-factor authentication

Existing MANET authentication schemes cannot fully protect nodes from well-known impersonation attacks. Although these schemes cryptographically link an entity to a claimed identity, the actual entity is never linked to the physical node device. However, the link is implicitly assumed. This shortcoming may be easily exploited within a MANET setting, due to the broadcast nature of the access medium. In this paper we propose a multifactor authentication framework that extends the cryptographic link, binding an entity to a physical node device. This is achieved by using two distinct authentication factors; certified keys and certified node characteristics. Although the proposed framework requires additional sensing capabilities from the MANET nodes, it provides the additional confidence level required for node authentication in critical applications.

Secure Multipath Routing for Mobile Ad Hoc Networks

Multipath routing minimizes the consequences of security attacks deriving from collaborating malicious nodes in MANET, by maximizing the number of nodes that an adversary must compromise in order to take control of the communication. In this paper, we identify several attacks that render multipath routing protocols more vulnerable than it is expected, to collaborating malicious nodes. We propose a novel on-demand multipath routing protocol, the Secure Multipath Routing protocol (SecMR) and we analyze its security properties. The SecMR protocol can be easily integrated in a wide range of on-demand routing protocols, such as DSR and AODV.

Risk assessment methodology for interdependent critical infrastructures

Assessing risk in interdependent infrastructures is a challenging topic due to its complexity and the nature of critical infrastructures. This paper describes a methodology for assessing the risk of an infrastructure or a sector, taking into account the presence of interdependencies between infrastructures and sectors. Although the proposed methodology is compatible with current information systems practices, our approach focuses on the consequences to the society and not on the infrastructure itself. The methodology is accompanied by a comprehensive case example.

Assessing n-order dependencies between critical infrastructures

The protection of critical infrastructures (CI) is a complex task, since it involves the assessment of both internal and external security risk. In the recent literature, methodologies have been proposed that can be used to identify organisation-wise security threats, or even first-order dependency risk (i.e., risk deriving from direct dependencies). However, there is a lack of work in the area of multi-order dependencies, i.e., assessing the cumulative effects of a single incident, on infrastructures that are connected indirectly. In this paper, we propose a method to identify and assess multi-order dependencies. Based on previous work, we utilise existing first-order dependency graphs, in order to assess the effect of a disruption to consequent infrastructures. In this way, it may be possible to identify and prevent security threats of very high impact from a macroscopic view, which would be hard to identify if we only examine first-order dependencies. We also present a scenario, which provides some evidence on the applicability of the proposed approach.

Hybrid key establishment for multiphase self-organized sensor networks

Recent work on key establishment for sensor networks has shown that it is feasible to employ limited elliptic curve cryptography in sensor networks through hybrid protocols. We propose a hybrid key establishment protocol for uniform self-organized sensor networks. The proposed protocol combines elliptic curve Diffie-Hellmann key establishment with implicit certificates and symmetric-key cryptographic techniques. The protocol can be implemented on uniform networks comprised of restricted functional devices. Furthermore, due to its public-key nature, the protocol is resilient to a wide range of passive and active attacks, such as known-key attacks, as well as attacks against the confidentiality, integrity and authenticity of the communication. The protocol is scalable and efficient for low-capability devices in terms of storage, communication and computational complexity; the cost per node for a key establishment is reduced to one scalar multiplication with a random point, plus one with a fixed point.

Interdependencies between Critical Infrastructures: Analyzing the Risk of Cascading Effects

One of the most challenging problems, when protecting critical infrastructures, is the identification and assessment of interdependencies. In this paper we examine the possible cumulative effects of a single security incident on multiple infrastructures. Our method provides a way to identify threats that may appear insignificant when examining only first-order dependencies, but may have potentially significant impact if one adopts a more macroscopic view and assesses multi-order dependencies. Based on previous work, we utilize existing first-order dependency graphs, in order to assess the effect of a disruption to consequent infrastructures.

Cascading Effects of Common-Cause Failures in Critical Infrastructures

One of the most challenging problems in critical infrastructure protection is the assessment and mitigation of cascading failures across infrastructures. In previous research, we have proposed a model for assessing the cumulative security risk of cascading threats due to high-order dependencies between infrastructures. However, recent empirical studies indicate that common-cause failures may result in extremely high impact situations, which may be comparable with or even more devastating than the cascading effects of high-order dependencies. This paper presents an extension to our model, which permits the assessment of the risk arising from complex situations involving multiple cascading failures triggered by major or concurrent common-cause events. The paper also discusses a realistic scenario that is used as a test case for the model extension.