Weakness of Key Predistribution Scheme Proposed by J. Dong et al.

A Sensor Node in Wireless Sensor Network has very limited resources such as processing capability, memory capacity, battery power, and communication capability. When the communication between any two sensor nodes are required to be secured, the symmetric key cryptography technique is used for its advantage over public key cryptography in terms of requirement of less resources. Keys are pre-distributed to each sensor node from a set of keys called key pool before deployment of sensors nodes. Combinatorial design helps in a great way to determine the way keys are drawn from the key pool for distributing to individual sensor nodes. J. Dong et al proposed a key predistribution scheme based on orthogonal array. We present the weakness of this predistribution scheme

Deterministic Merging of Blocks in Combinatorial Design based Key Predistribution in Distributed Wireless Sensor Network

Sensor nodes have severe constraints in terms of its resources such as processing power, memory, communication range, battery power. Due to wireless nature of communication between nodes in a wireless sensor network, any attacker can intercept the communicating messages between sensor nodes. So the need for securing these messages is obvious. Due to resource constraints of sensor nodes, public key cryptography can’t be employed for securing the communication as public key cryptography demands much computational effort. So, private key cryptography is natural choice for securing the communication in wireless sensor network. Key predistribution has become obvious choice for distributing keys in sensor nodes for secured communication in a wireless sensor network. A pool of keys is first taken, and then a set of keys from this key pool is installed in every sensor node before their deployment. The keys predistributed to a particular sensor node can be drawn from the key pool probabilistically or deterministically. Combinatorial design which was originated as a branch of statistics and later found its vast application in coding theory and of late in cryptography plays a vital role in deterministic key predistribution. The connectivity and resiliency offered by some combinatorial design based key predistribution schemes can be sometimes offered by merging of blocks and then assign these merged blocks to sensor nodes. The question is how to choose blocks for merging? There is a prior general work on merging of blocks which has been studied on transversal design based key predistribution scheme. This approach is not deterministic, but heuristic. A deterministic algorithm for merging of blocks has been proposed. The orthogonal array based key predistribution scheme has been studied in detail and the non suitability of merging approach to improve its performance has been shown. In addition, a key establishment algorithm for transversal design based key predistribution scheme has been proposed

A key distribution scheme tailored for mobile sensor networks

Wireless Sensor Networks, (WSN), are composed of battery-powered and resource-limited small devices called sensor nodes. WSNs are used for sensing and collecting data in the deployment area to be relayed to a Base Station (BS). In order to secure WSNs, first of all key distribution problems must be addressed. Key distribution problem is extensively studied for static WSNs, but has not been studied widely for mobile WSNs (MWSN). In this thesis, we proposed key distribution mechanisms for MWSNs. We propose a scheme in which both sensor nodes and the BS are mobile. In our scheme, the BS works as a key distribution center as well. It continuously moves in the environment and distributes pairwise keys to neighboring sensor nodes. In this way, the network gets securely connected. We conduct simulations to analyze the performance of our proposed scheme. The results show that our scheme achieves a local connectivity value of 0.73 for half-mobile network scenario and 0.54 for fully-mobile network scenario. These values can be further improved by using multiple BSs or increasing the speed of the BS. Moreover, our scheme provides perfect resiliency; an adversary cannot compromise any additional links using the captured nodes. We also incorporate two well-known key distribution mechanisms used for static networks into our scheme and provide a better connectivity in the early stages of the sensor network. The improvement in local connectivity, however, comes at the expense of reduced resiliency at the beginning. Nevertheless, the resiliency improves and connectivity converges to our original scheme's values in time

Security of Ubiquitous Computing Systems

The chapters in this open access book arise out of the EU Cost Action project Cryptacus, the objective of which was to improve and adapt existent cryptanalysis methodologies and tools to the ubiquitous computing framework. The cryptanalysis implemented lies along four axes: cryptographic models, cryptanalysis of building blocks, hardware and software security engineering, and security assessment of real-world systems. The authors are top-class researchers in security and cryptography, and the contributions are of value to researchers and practitioners in these domains. This book is open access under a CC BY license

Secure Protocols for Key Pre-distribution, Network Discovery, and Aggregation in Wireless Sensor Networks

The term sensor network is used to refer to a broad class of networks where several small devices, called sensors, are deployed in order to gather data and report back to one or more base stations. Traditionally, sensors are assumed to be small, low-cost, battery-powered, wireless, computationally constrained, and memory constrained devices equipped with some sort of specialized sensing equipment. In many settings, these sensors must be resilient to individual node failure and malicious attacks by an adversary, despite their constrained nature. This thesis is concerned with security during all phases of a sensor network's lifetime: pre-deployment, deployment, operation, and maintenance. This is accomplished by pre-loading nodes with symmetric keys according to a new family of combinatorial key pre-distribution schemes to facilitate secure communication between nodes using minimal storage overhead, and without requiring expensive public-key operations. This key pre-distribution technique is then utilized to construct a secure network discovery protocol, which allows a node to correctly learn the local network topology, even in the presence of active malicious nodes. Finally, a family of secure aggregation protocols are presented that allow for data to be efficiently collected from the entire network at a much lower cost than collecting readings individually, even if an active adversary is present. The key pre-distribution schemes are built from a family of combinatorial designs that allow for a concise mathematical analysis of their performance, but unlike previous approaches, do not suffer from strict constraints on the network size or number of keys per node. The network discovery protocol is focused on providing nodes with an accurate view of the complete topology so that multiple node-disjoint paths can be established to a destination, even if an adversary is present at the time of deployment. This property allows for the use of many existing multi-path protocols that rely on the existence of such node-disjoint paths. The aggregation protocols are the first designed for simple linear networks, but generalize naturally to other classes of networks. Proofs of security are provided for all protocols

On Enhancements of Physical Layer Secret Key Generation and Its Application in Wireless Communication Systems

As an alternative and appealing approach to providing information security in wireless communication systems, secret key generation at physical layer has demonstrated its potential in terms of efficiency and reliability over traditional cryptographic methods. Without the necessity of a management centre for key distribution or reliance on computational complexity, physical layer key generation protocols enable two wireless entities to extract identical and dynamic keys from the randomness of the wireless channels associated with them. In this thesis, the reliability of secret key generation at the physical layer is examined in practical wireless channels with imperfect channel state information (CSI). Theoretical analyses are provided to relate key match rate with channel\u27s signal-to-noise ratio (SNR), degrees of channel reciprocity, and iterations of information reconciliation. In order to increase key match rate of physical layer secret key generation, improved schemes in the steps of channel estimation and sample quantization are proposed respectively. In the channel estimation step, multiple observations of the wireless channels are integrated with a linear processor to provide a synthesized and more accurate estimation of the wireless channel. In the sample quantization step, a magnitude based quantization method with two thresholds is proposed to quantize partial samples, where specific quantization areas are selected to reduce cross-over errors. Significant improvements in key match rate are proven for both schemes in theoretical analysis and numerical simulations. Key match rate can even achieve 100% in both schemes with the assistance of information reconciliation process. In the end, a practical application of physical layer secret key generation is presented, where dynamic keys extracted from the wireless channels are utilized for securing secret data transmission and providing efficient access control

Smart Wireless Sensor Networks

The recent development of communication and sensor technology results in the growth of a new attractive and challenging area - wireless sensor networks (WSNs). A wireless sensor network which consists of a large number of sensor nodes is deployed in environmental fields to serve various applications. Facilitated with the ability of wireless communication and intelligent computation, these nodes become smart sensors which do not only perceive ambient physical parameters but also be able to process information, cooperate with each other and self-organize into the network. These new features assist the sensor nodes as well as the network to operate more efficiently in terms of both data acquisition and energy consumption. Special purposes of the applications require design and operation of WSNs different from conventional networks such as the internet. The network design must take into account of the objectives of specific applications. The nature of deployed environment must be considered. The limited of sensor nodes� resources such as memory, computational ability, communication bandwidth and energy source are the challenges in network design. A smart wireless sensor network must be able to deal with these constraints as well as to guarantee the connectivity, coverage, reliability and security of network's operation for a maximized lifetime. This book discusses various aspects of designing such smart wireless sensor networks. Main topics includes: design methodologies, network protocols and algorithms, quality of service management, coverage optimization, time synchronization and security techniques for sensor networks

Security in Distributed, Grid, Mobile, and Pervasive Computing

This book addresses the increasing demand to guarantee privacy, integrity, and availability of resources in networks and distributed systems. It first reviews security issues and challenges in content distribution networks, describes key agreement protocols based on the Diffie-Hellman key exchange and key management protocols for complex distributed systems like the Internet, and discusses securing design patterns for distributed systems. The next section focuses on security in mobile computing and wireless networks. After a section on grid computing security, the book presents an overview of security solutions for pervasive healthcare systems and surveys wireless sensor network security