Group Key Management in Wireless Ad-Hoc and Sensor Networks

A growing number of secure group applications in both civilian and military domains is being deployed in WAHNs. A Wireless Ad-hoc Network (WARN) is a collection of autonomous nodes or terminals that communicate with each other by forming a multi-hop radio network and maintaining connectivity in a decentralized manner. A Mobile Ad-hoc Network (MANET) is a special type of WARN with mobile users. MANET nodes have limited communication, computational capabilities, and power. Wireless Sensor Networks (WSNs) are sensor networks with massive numbers of small, inexpensive devices pervasive throughout electrical and mechanical systems and ubiquitous throughout the environment that monitor and control most aspects of our physical world. In a WAHNs and WSNs with un-trusted nodes, nodes may falsify information, collude to disclose system keys, or even passively refuse to collaborate. Moreover, mobile adversaries might invade more than one node and try to reveal all system secret keys. Due to these special characteristics, key management is essential in securing such networks. Current protocols for secure group communications used in fixed networks tend to be inappropriate. The main objective of this research is to propose, design and evaluate a suitable key management approach for secure group communications to support WAHNs and WSNs applications. Key management is usually divided into key analysis, key assignment, key generation and key distribution. In this thesis, we tried to introduce key management schemes to provide secure group communications in both WAHNs and WSNs. Starting with WAHNs, we developed a key management scheme. A novel architecture for secure group communications was proposed. Our proposed scheme handles key distribution through Combinatorial Key Distribution Scheme (CKDS). We followed with key generation using Threshold-based Key Generation in WAHNs (TKGS). For key assignment, we proposed Combinatorial Key Assignment Scheme (CKAS), which assigns closer key strings to co-located nodes. We claim that our architecture can readily be populated with components to support objectives such as fault tolerance, full-distribution and scalability to mitigate WAHNs constraints. In our architecture, group management is integrated with multicast at the application layer. For key management in WSNs, we started with DCK, a modified scheme suitable for WSNs. In summary, the DCK achieves the following: (1) cluster leader nodes carry the major part of the key management overhead; (2) DCK consumes less than 50% of the energy consumed by SHELL in key management; (3) localizing key refreshment and handling node capture enhances the security by minimizing the amount of information known by each node about other portions of the network; and (4) since DCK does not involve the use of other clusters to maintain local cluster data, it scales better from a storage point of view with the network size represented by the number of clusters. We went further and proposed the use of key polynomials with DCK to enhance the resilience of multiple node capturing. Comparing our schemes to static and dynamic key management, our scheme was found to enhance network resilience at a smaller polynomial degree t and accordingly with less storage per node

Key Management Systems for Smart Grid Advanced Metering Infrastructure: A Survey

Smart Grids are evolving as the next generation power systems that involve changes in the traditional ways of generation, transmission and distribution of power. Advanced Metering Infrastructure (AMI) is one of the key components in smart grids. An AMI comprises of systems and networks, that collects and analyzes data received from smart meters. In addition, AMI also provides intelligent management of various power-related applications and services based on the data collected from smart meters. Thus, AMI plays a significant role in the smooth functioning of smart grids. AMI is a privileged target for security attacks as it is made up of systems that are highly vulnerable to such attacks. Providing security to AMI is necessary as adversaries can cause potential damage against infrastructures and privacy in smart grid. One of the most effective and challenging topic's identified, is the Key Management System (KMS), for sustaining the security concerns in AMI. Therefore, KMS seeks to be a promising research area for future development of AMI. This survey work highlights the key security issues of advanced metering infrastructures and focuses on how key management techniques can be utilized for safeguarding AMI. First of all, we explore the main features of advanced metering infrastructures and identify the relationship between smart grid and AMI. Then, we introduce the security issues and challenges of AMI. We also provide a classification of the existing works in literature that deal with secure key management system in AMI. Finally, we identify possible future research directions of KMS in AMI

Efficient Security Protocols for Fast Handovers in Wireless Mesh Networks

Wireless mesh networks (WMNs) are gaining popularity as a flexible and inexpensive replacement for Ethernet-based infrastructures. As the use of mobile devices such as smart phones and tablets is becoming ubiquitous, mobile clients should be guaranteed uninterrupted connectivity and services as they move from one access point to another within a WMN or between networks. To that end, we propose a novel security framework that consists of a new architecture, trust models, and protocols to offer mobile clients seamless and fast handovers in WMNs. The framework provides a dynamic, flexible, resource-efficient, and secure platform for intra-network and inter-network handovers in order to support real-time mobile applications in WMNs. In particular, we propose solutions to the following problems: authentication, key management, and group key management. We propose (1) a suite of certificate-based authentication protocols that minimize the authentication delay during handovers from one access point to another within a network (intra-network authentication). (2) a suite of key distribution and authentication protocols that minimize the authentication delay during handovers from one network to another (inter-network authentication). (3) a new implementation of group key management at the data link layer in order to reduce the group key update latency from linear time (as currently done in IEEE 802.11 standards) to logarithmic time. This contributes towards minimizing the latency of the handover process for mobile members in a multicast or broadcast group

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

Key management for wireless sensor network security

Wireless Sensor Networks (WSNs) have attracted great attention not only in industry but also in academia due to their enormous application potential and unique security challenges. A typical sensor network can be seen as a combination of a number of low-cost sensor nodes which have very limited computation and communication capability, memory space, and energy supply. The nodes are self-organized into a network to sense or monitor surrounding information in an unattended environment, while the self-organization property makes the networks vulnerable to various attacks.Many cryptographic mechanisms that solve network security problems rely directly on secure and efficient key management making key management a fundamental research topic in the field of WSNs security. Although key management for WSNs has been studied over the last years, the majority of the literature has focused on some assumed vulnerabilities along with corresponding countermeasures. Specific application, which is an important factor in determining the feasibility of the scheme, has been overlooked to a large extent in the existing literature.This thesis is an effort to develop a key management framework and specific schemes for WSNs by which different types of keys can be established and also can be distributed in a self-healing manner; explicit/ implicit authentication can be integrated according to the security requirements of expected applications. The proposed solutions would provide reliable and robust security infrastructure for facilitating secure communications in WSNs.There are five main parts in the thesis. In Part I, we begin with an introduction to the research background, problems definition and overview of existing solutions. From Part II to Part IV, we propose specific solutions, including purely Symmetric Key Cryptography based solutions, purely Public Key Cryptography based solutions, and a hybrid solution. While there is always a trade-off between security and performance, analysis and experimental results prove that each proposed solution can achieve the expected security aims with acceptable overheads for some specific applications. Finally, we recapitulate the main contribution of our work and identify future research directions in Part V

Self-Protecting Access Control: On Mitigating Privacy Violations with Fault Tolerance

Self-protecting access control mechanisms can be described as an approach to enforcing security in a manner that automatically protects against violations of access control rules. In this chapter, we present a comparative analysis of standard Cryptographic Access Control (CAC) schemes in relation to privacy enforcement on the Web. We postulate that to mitigate privacy violations, self-protecting CAC mechanisms need to be supported by fault-tolerance. As an example of how one might to do this, we present two solutions that are inspired by the autonomic computing paradigm1. Our solutions are centered on how CAC schemes can be extended to protect against privacy violations that might arise from key updates and collusion attacks

Privacy-preserving spatiotemporal multicast for mobile information services

Mobile devices have become essential for accessing information services anywhere at any time. While the so-called geographic multicast (geocast) has been considered in detail in existing research, it only focuses on delivering messages to all mobile devices that are currently residing within a certain geographic area. This thesis extends this notion by introducing a Spatiotemporal Multicast (STM), which can informally be described as a "geocast into the past". Instead of addressing users based on their current locations, this concept relates to the challenge of sending a message to all devices that have resided within a geographic area at a certain time in the past. While a wide variety of applications can be envisioned for this concept, it presents several challenges to be solved. In order to deliver messages to all past visitors of a certain location, an STM service would have to fully track all user movements at all times. However, collecting this kind of information is not desirable considering the underlying privacy implications, i.e., users may not wish to be identified by the sender of a message as this can disclose sensitive personal information. Consequently, this thesis aims to provide a privacy-preserving notion of STM. In order to realize such a service, this work first presents a detailed overview of possible applications. Based on those, functional, non-functional, as well as security and privacy objectives are proposed. These objectives provide the foundation for an in-depth literature review of potential mechanisms for realizing an STM service. Among the suggested options, the most promising relies on Rendezvous Points (RPs) for datagram delivery. In simple terms, RPs represent "anonymous mailboxes" that are responsible for certain spatiotemporal regions. Messages are deposited at RPs so that users can retrieve them later on. Protecting the privacy of users then translates to obfuscating the responsibilities of RPs for specific spatiotemporal regions. This work proposes two realizations: CSTM, which relies on cryptographic hashing, and OSTM, which considers the use of order-preserving encryption in a CAN overlay. Both approaches are evaluated and compared in detail with respect to the given objectives. While OSTM yields superior performance-related properties, CSTM provides an increased ability of protecting the privacy of users.Mobilgeräte bilden heute die Grundlage allgegenwärtiger Informationsdienste. Während der sogenannte geografische Multicast (Geocast) hier bereits ausführlich erforscht worden ist, so bezieht sich dieser nur auf Geräte, welche sich aktuell innerhalb einer geografischen Zielregion befinden. Diese Arbeit erweitert dieses Konzept durch einen räumlich-zeitlichen Multicast, welcher sich informell als "Geocast in die Vergangenheit" beschreiben lässt. Dabei wird die Zustellung einer Nachricht an alle Nutzer betrachtet, die sich in der Vergangenheit an einem bestimmten Ort aufgehalten haben. Während eine Vielzahl von Anwendungen für dieses Konzept denkbar ist, so ergeben sich hier mehrere Herausforderungen. Um Nachrichten an ehemalige Besucher eines Ortes senden zu können, müsste ein räumlich-zeitlicher Multicast-Dienst die Bewegungen aller Nutzer vollständig erfassen. Aus Gründen des Datenschutzes ist das zentralisierte Sammeln solch sensibler personenbezogener Daten jedoch nicht wünschenswert. Diese Arbeit befasst sich daher insbesondere mit dem Schutz der Privatsphäre von Nutzern eines solchen Dienstes. Zur Entwicklung eines räumlich-zeitlichen Multicast-Dienstes erörtert diese Arbeit zunächst mögliche Anwendungen. Darauf aufbauend werden funktionale, nicht-funktionale, sowie Sicherheits- und Privatsphäre-relevante Anforderungen definiert. Diese bilden die Grundlage einer umfangreichen Literaturrecherche relevanter Realisierungstechniken. Der vielversprechendste Ansatz basiert hierbei auf der Hinterlegung von Nachrichten in sogenannten Rendezvous Points. Vereinfacht betrachtet stellen diese "anonyme Briefkästen" für bestimmte räumlich-zeitliche Regionen dar. Nachrichten werden in diesen so hinterlegt, dass legitime Empfänger sie dort später abholen können. Der Schutz der Nutzer-Privatsphäre entspricht dann der Verschleierung der Zuständigkeiten von Rendezvous Points für verschiedene räumlich-zeitliche Regionen. Diese Arbeit schlägt zwei Ansätze vor: CSTM, welches kryptografische Hashfunktionen nutzt, sowie OSTM, welches ordnungserhaltende Verschlüsselung in einem CAN Overlay einsetzt. Beide Optionen werden detailliert analytisch sowie empirisch bezüglich ihrer Diensteigenschaften untersucht und verglichen. Dabei zeigt sich, dass OSTM vorteilhaftere Leistungseigenschaften besitzt, während CSTM einen besseren Schutz der Nutzer-Privatsphäre bietet

Key Management Scheme for Smart Grid

A Smart Grid (SG) is a modern electricity supply system. It uses information and communication technology (ICT) to run, monitor and control data between the generation source and the end user. It comprises a set of technologies that uses sensing, embedded processing and digital communications to intelligently control and monitor an electricity grid with improved reliability, security, and efficiency. SGs are classified as Critical Infrastructures. In the recent past, there have been cyber-attacks on SGs causing substantial damage and loss of services. A recent cyber-attack on Ukraine's SG caused over 2.3 million homes to be without power for around six hours. Apart from the loss of services, some portions of the SG are yet to be operational, due to the damage caused. SGs also face security challenges such as confidentiality, availability, fault tolerance, privacy, and other security issues. Communication and networking technologies integrated into the SG require new and existing security vulnerabilities to be thoroughly investigated. Key management is one of the most important security requirements to achieve data confidentiality and integrity in a SG system. It is not practical to design a single key management scheme/framework for all systems, actors and segments in the smart grid, since the security requirements of various sub-systems in the SG vary. We address two specific sub-systems categorised by the network connectivity layer – the Home Area Network (HAN) and the Neighbourhood Area Network (NAN). Currently, several security schemes and key management solutions for SGs have been proposed. However, these solutions lack better security for preventing common cyber-attacks such as node capture attack, replay attack and Sybil attack. We propose a cryptographic key management scheme that takes into account the differences in the HAN and NAN segments of the SG with respect to topology, authentication and forwarding of data. The scheme complies with the overall performance requirements of the smart grid. The proposed scheme uses group key management and group authentication in order to address end-to-end security for the HAN and NAN scenarios in a smart grid, which fulfils data confidentiality, integrity and scalability requirements. The security scheme is implemented in a multi-hop sensor network using TelosB motes and ZigBee OPNET simulation model. In addition, replay attack, Sybil attack and node capture attack scenarios have been implemented and evaluated in a NAN scenario. Evaluation results show that the scheme is resilient against node capture attacks and replay attacks. Smart Meters in a NAN are able to authenticate themselves in a group rather than authenticating one at a time. This significant improvement over existing schemes is discussed with comparisons with other security schemes