Summary In the world of large‐scale applications, software as a service (SaaS) in general and use of microservices, in particular, is bringing service‐oriented architectures to a new level: Systems in general and systems that interact with human users (eg, sociotechnical systems) in particular are built by composing microservices that are developed independently and operated by different parties. At the same time, SaaS applications are used more and more widely by enterprises as well as public services for providing critical services, including those processing security or privacy of relevant data. Therefore, providing secure and reliable service compositions is increasingly needed to ensure the success of SaaS solutions. Building such service compositions securely is still an unsolved problem. In this paper, we present a framework for modelling, validating, and ranking secure service compositions that integrate both automated services as well as services that interact with humans. As a unique feature, our approach for ranking services integratesvalidated properties(eg, based on the result of formally analysing the source code of a service implementation) as well ascontractual propertiesthat are part of the service level agreement and, thus, not necessarily ensured on a technical level.

Abstract In multihop networks such as mobile ad hoc networks selfish or misbehaving nodes can degrade network performance. Reputation and trust‐based schemes have been proposed in order to enforce cooperation and to discourage misbehaving nodes. These schemes detect and isolate selfish nodes and maintain network throughput by enabling nodes to construct paths that only include good nodes. In order to punish selfish nodes and restrict their services, selfish nodes are not provided with packet forwarding services anymore by the good nodes in the network. The aim of these schemes is to increase good nodes' benefit (throughput and utility) and to decrease malicious nodes' benefit. In this paper, we demonstrate that the commonly adopted simulation parameters used by the research community for the evaluation of reputation or trust‐based schemes in mobile environments usually produce biased results. We further demonstrate this fact by adopting a widely used reputation‐based scheme as our case study using the commonly used metrics, such as throughput, utility, delay, and overhead. The simulation parameters are analyzed analytically and via simulations in order to demonstrate their main reason of producing inaccurate and biased results. Finally, we compare simulation and analytical results to corroborate our claim and discuss how to mitigate the resulted inaccuracy and biasness. Copyright © 2015 John Wiley & Sons, Ltd.

Service-oriented environments provide the opportunity for services from different providers to work together, forming new composite services via composition of existing services. However, in addition to the intended outcomes, composition also introduces the potential for unexpected or emergent behaviour, resulting in new uncertainties, especially in the area of security. Funded by the European FP7 programme, our research focusses on providing a service composition platform that is secure and trustworthy. We will demonstrate the design-time prototype that show how to create service compositions, verify them against security policies and make sensible recommendations based on a user's security preferences.

The unique characteristics of a system-of-systems (SoS) environment pose many significant technical challenges when it comes to monitoring the behaviour of its component systems. In this collaborative environment, component misbehaviour is one of the most significant security threats. A key countermeasure is the ability to detect behaviour that could jeopardise the integrity, availability or functionality of either the composition or its components. However, due to the heterogeneity of the environment, as well as the uncertainty and dynamics of both the structure and function, component system behaviour is highly dynamic and unpredictable. This poses challenges for existing techniques and casts doubt over their reliability and effectiveness. Therefore potentially allowing behavioural threats to evade detection and yielding high false positive rates. In this paper, we will outline the security concerns that misbehaviour poses in terms of both individual components and the SoS as a whole. We will also propose our novel monitoring framework, which is designed to overcome the challenges of monitoring in a SoS environment. This paper also details our implementation and presents some of our initial results.

Big animated film companies these days are migrating their operations to the advent technology of cloud computing. They need quick access to massive amounts of computer power from the cloud to generate a photorealistic animated film within reasonable time and cost as well. However, moving private data to untrusted third parties like clouds raises security concerns. Primitive encryption schemes seem ineffective to be used as the data need to be decrypted first. Thus, homomorphic encryption is believed to be one of the potential solutions as it allows arbitrary computation on encrypted data without decryption. There are a number of fully homomorphic encryption (FHE) schemes that have been proposed and improved upon. Nevertheless, all of them are far from practical as efficiency is still a big obstacle for their implementation. Thus, in this paper a new FHE scheme based on finite fields and support n-multilinear maps is proposed. The key contribution of this paper is to propose a FHE scheme with improved efficiency. To implement such a scheme, a new protocol is proposed. The protocol allows three or more parties to communicate with one another to process data in an encrypted form.

ABSTRACT Wireless sensor networks (WSNs) often consist of tiny devices and offer a variety of potential means to monitor the environment. However, WSNs are vulnerable to several types of attack because of their use in critical applications, their deployment in open and unprotected environments and their limited system resources. Therefore, security design is an important aspect of WSNs. In this work, we focus on detecting misbehaving nodes in WSNs. To the best of our knowledge, we are the first to present a complete and formal study on finding optimised monitor nodes and combining the organisation of the network with monitoring for misbehaviour detection in WSNs. The main idea of this work is to propose simple and efficient distributed monitoring algorithm capable of detecting misbehaviours based on a clustered architecture, where the cluster head is elected according to a new set of metrics. These new election metrics are based on a multiple‐criteria decision approach in order to monitor the health status of cluster members and detect misbehaviour. Our proposed strategy ensures a good selection of the nodes responsible for monitoring, reduces energy consumption during the monitoring process—effectively reducing the amount of security information that flows through the network—and reduces latency. The efficiency of our method is evaluated through simulation experiments. Copyright © 2012 John Wiley & Sons, Ltd.

ABSTRACT In the last decade, many security solutions have been proposed to fulfil the security requirements of wireless sensor networks (WSNs). However, these solutions are specifically designed for particular security issues, based on different assumptions, and limited to certain WSNs applications. Can these security solutions work together to handle multiple problems at the same time? It is an interesting and difficult question. We believe good solutions in various security areas do not mean they can work together and deliver similar results, i.e. occurrence of any security weakness or attack in a particular security solution could expose the vulnerabilities of other solutions. Using these solutions together might also degrade WSN quality of service. To deal with the aforementioned issues, we therefore propose a novel component‐based security system (COMSEC) based on proactive and reactive components. Each component looks after a particular security issue and is integrated with others. The proposed system provides better secure communication, Sybil attack detection, secure data aggregation and resilience against node capture attacks and replication attacks. COMSEC has been evaluated and compared against existing schemes. Evaluation results show a significant improvement in resilience against node capture attacks, Sybil attack detection data confidentiality, privacy, memory overhead and connectivity. Copyright © 2012 John Wiley & Sons, Ltd.

There is growing global concern over the growing levels of obesity and the fact that people in general are not as active as they once were. Many believe that this is directly related to poor diet and our increasing reliance on technology, such as television, social networking, computer games, and voice activated home control systems. These kinds of activities increase sedentary behaviour across all age groups and is considered one of the main contributors to obesity and poor health. For this reason decreasing sedentary behaviour is considered a crucial theme within many research programs in health. Ironically, there is general agreement that the use of technology is likely to help researchers understand this type of behaviour. One interesting approach is based upon the use of human digital memories to provide visual lifelogs of a user's activity and to identify the behaviour patterns of individuals. In this way visual lifelogs provide a way for user's to evaluate their lifestyle choices. This paper discusses some of the key technologies used to achieve this and considers some of the challenges that still need to be addressed.

Level of detail (LoD) techniques provide efficient and established tools to represent 3D models, while these are well documented and applied with proven results there is not much research and proven results that offer a solution that is both compatible with MPEG-4 (Motion Picture Experts Group) facial animation standard, and which considers a human face mesh simplification. In this paper we present our work on an adaptive LoD algorithm and attempt to preserve the human face features and simplify animation streams when possible by analyzing the scene and the model. Our approach is to apply continuous LOD to a MPEG-4 compliant model using an extension of Garland's Quadric-Based Surface algorithm. This is achieved with a novel approach that attempts a selective model simplification that is both compatible with MPEG-4 and also could simplify animation streams.

Digital Interactive Storytelling (DIS) is a relatively new field of interactive computer entertainment which aims at creating interactive applications capable of generating consistent and rich narratives. Planning systems are the most widely used techniques for DIS, however there have not been much novel solutions for DIS research with respect to developing new planning algorithms. Not only no DIS dedicated planning algorithm has been proposed, but when general-purpose AI planning algorithms are being used in DIS, the justification of the algorithm's choice is usually inadequate. In this paper we propose an evaluation of planning algorithms for DIS and discuss the results in the context of related works.

There is growing concern, among senior personnel in the National Health Service in the UK, over the increased development of pressure ulcers. The occurrence of pressure ulcers has been attributed to prolong sedentary behaviour. Providing care, for this preventable condition, is costly and time-consuming for patients and medical practitioners. Extra bedside assistance is needed; however, with the workload of medical staff increasing, this is not always practical. In order to prevent the occurrence of pressure ulcers new and novel ways of remotely monitoring patients is essential. An interesting approach worth considering is the use of human digital memories, which provide visual life logs of a patient's physiological and environmental data. This paper discusses some of the current technologies used within the area and how they might be applied to the management and prevention of pressure ulcers. We have successfully developed a working prototype system to demonstrate the applicability of our approach.

In this paper we discuss the issues relating to architecture formation in MMOGs and the two principal design choices that must be made when constructing a Peer-to-Peer (P2P) MMOG: the Area of Interest Management (AoIM) scheme and the distribution and communication mechanism. We introduce an updated survey of the state-of-the-art of AoIM in P2P Online Games. We identify key issues in the development and deployment of such architectures. We analyze the main features of existing solutions. The contribution of the paper is a novel perspective in understanding the limitations of existing solutions and discussing the design criteria for an alternative P2P approach to alleviate scalability issues.

Cognitive radio is considered as a new paradigm of designing wireless communication systems that aims at improving the spectrum utilization. Spectrum sensing is one of the most important elements in cognitive radio networks. Many spectrum sensing algorithms have been proposed in the literature. Among these algorithms, energy detection has been widely used in practice because of its computational and implementation simplicities. However, the performance of conventional energy detection is greatly deteriorating due to the impact of noise uncertainty, especially in low signal to noise ratio SNR environments. On the other hand, the inappropriate setting of the detection threshold could leads to a significant decline in the performance of detection. In this paper, we explore these situations and we propose an energy detection based optimal threshold scheme. We derived an optimal threshold level based on the tradeoff between misdetection probability and false alarm probability. We also developed an adaptive threshold factor with optimal algorithm in order to combat the noise uncertainty which is compatible with the real world communications and that allows gaining better spectrum sensing performance especially in low SNR.

The correct functioning of critical infrastructures is crucial for modern society. These systems provide the backbone to our everyday lives and, therefore, securing and protecting them is a challenging yet vital issue. This project studies the vulnerabilities and protection challenges these systems present, and proposes a solution using a collaborative multi-user game-based visualisation interface. This project proposes a tool that models and represents a complex system in an easy-to-understand, comprehensive manner, enabling all those involved in monitoring the system to detect problems and threats, and make better informed security decisions. The game-like interface allows a real-time coordinated response from all the different stakeholders involved in controlling and protecting the system. The interface will resemble a massively-multiplayer online game (MMOG), in which different users with different roles and access levels will have a personalised view of the system and react to security warnings in order to protect the system.

In multihop networks such as mobile ad hoc networks selfish or misbehaving nodes can degrade network performance. Reputation based models have been developed to enforce cooperation and to discourage node misbehaviour. These schemes detect and isolate selfish nodes and maintain network throughput by enabling nodes to construct paths that only include good nodes. In order to punish selfish nodes and restrict their services, selfish nodes are not provided with packet forwarding services anymore by the good nodes in the network; however they can still gain throughput or utility by interacting directly with the destination nodes. The commonly adopted simulation parameters used by the research community for the evaluation of reputation based schemes in mobile environments usually produces high direct interactions. These direct interactions result in noticeably higher throughput and node utility for the network overall causing confusion: these metrics are increased or decreased due to the direct interactions or due to the reputation based scheme. We implemented the popular CONFIDANT reputation-based scheme to confirm how much throughput is the result of these direct interactions. Our simulation studies show that in the presence of 20% selfish nodes and in a continuous mobile environment, 59% of the evil throughput and 29% of the good throughput was gained through direct interactions among nodes. These direct interactions accordingly affect delay and routing overhead in the network.

Procedural methods show great potential but are an underused substitute to manual content creation. Limitations to these methods include the lack of control of the output due to its random nature and the absence of integrated solutions, although more recent publications increasingly address these issues. This paper describes procedural methods applied to 3D game environment, including the variable realism of their output, performance and the control users can exercise over the procedure. In this work, we focus on the techniques and processes we used to create a web based tool in Java that creates and exports a variety of 3D computer game levels using procedural content generation with random and user selected constraints. The system also supports 3D hardware acceleration.

How to design effective learning opportunities? Why is learning by experience often more efficient than learning by studying? How to provide the learning experiences needed to respond to current challenges? Using computer games and games in general for educational purposes offers a variety of knowledge presentations and creates opportunities to apply the knowledge within a virtual world, thus supporting and facilitating the learning process. This paper introduces a system based on constructivist theory - design game based learning for dinosaurs life teaching, and use Homura 3D to implement the dinosaur learning application.

Critical infrastructures play important roles in ensuring the wellbeing of the populace. Protecting critical infrastructures and ensuring their continued operation will be an important part of future Smart City ecosystems. Minimising the destruction of failing critical infrastructure components or system components that are geographically close critical services is essential. Equally important are the system of systems relationships that a failing system has, as these could render a minor system critical under certain circumstances. Infrastructure failure is usually brought under control through system adaptation e.g. using sensor area networks to close valves or by emergency response e.g. extinguishing fires. Current response procedures rely on antiquated information sharing techniques and provide little or no opportunity to effect change within the failing infrastructures systems. There may also be minimal understanding of the important systems of systems role that is being provided by components of the failing system. This paper details our initial work on the Smart Cities Critical Infrastructure response framework. The goal of our framework is to provide a response strategy to first responders based on smart cities information flows. Where these information flows have been compromised we propose a robust infrastructure state preservation system as to provide an interface to a failing critical infrastructure.

The past 20 years of facial modeling and animation research have focused on improving facial animation systems' believability, realism, flexibility, and applicability. The MPEG-4 standards define a technique for 3D facial and body model animations (FAPS / BAPS respectively), as seen in modern animation systems. The way this technique works is in contrast to the set of animation techniques currently used within modern games technologies and applications, which utilize more advanced, expressive animation systems such as Skeletal, Morph Target and Inverse Kinematics. This paper introduces a 3D Homura based framework for the integration and transformation of MPEG4 standards-compliant highly realistic animation streams known as Charisma, which can be applied for use with modern games animation systems and virtual characters in the web. This paper reports the development and the very good performance framework on top of our Java / OpenGL-based games engine framework Homura.

The smart grid will deliver electricity from suppliers to consumers using digital technology to save energy, reduce cost and increase reliability and transparency. The realization of the smart grid requires the modernization of the control system that governs the electricity supply process. The power grid will be instrumented with thousands of new digital control devices, sensors, and smart meters. Although the introduction of these technologies will bring many benefits to the control of the power networks, it will add more complexity to the communications. These new control entities will generate a huge amount of data and consume a portion of the communication bandwidth that may be needed for other control operations. In this paper we propose to use data aggregation techniques that allow reducing the communication overhead resulting from the introduction of the wireless sensor networks. We show that by using data aggregation functions, the communication traffic generated by smart sensors can be reduced, hence saving precious transmission bandwidth for other control operations.

Information and communications technology influences many of the activities we perform on any given day. Through the widespread availability and use of consumer electronics we have almost augmented ourselves to permanently form part of technology. This has provided a platform capable of supporting fluid information flows anytime and anywhere and has opened up great opportunities across many sectors. However, it is perhaps the healthcare sector that may offer the greatest rewards. Now that people have permanent links to digital services new and novel applications can be developed, i.e. preventative medical services to help fight debilitating illnesses, such as arthritis. By employing real-time monitoring and analysis patients can be guided, based on their daily activities to prevent or mitigate the effects some activities may have on the body. In this paper we explore this notion and provide a framework to allow real-time monitoring of arthritic conditions in the home. The aim is to embed devices (inner and out body sensors, including home sensor networks) to collect data that can be used to analyse activity around body joints (progressive destruction of cartilage and bone) and inform patients about aggravated activity. We have successfully demonstrated the applicability of our approach using a working prototype system.

The home is becoming more embedded with wireless technologies and digital services. For example, machine-to-machine solutions for utility billing and management are now possible using cellular networks. With many homes now supporting different communication capabilities it has become relatively easy to deploy ubiquitous devices (sensors) and services for any number of different applications. This is already practical where probing the home network often uncovers services not necessarily known beforehand, i.e. universal plug-n-play devices like cable modems provide passive interactive services. Invisible services like these are set to accelerate as more networked devices form part of the home itself. Consequently, there will be a need to visualise available devices or services in order to allow users to better exploit the functions they provide. In this paper we embark on such an approach whereby a visualisation tool is placed over home networks to help achieve this. In this way devices can be seen irrespective of how invisible technology becomes, providing better exploitation of the services they provide. A successful case study is presented to demonstrate the applicability of our approach.

Digital watermarking is one of the most widely used techniques for protection of ownership rights of digital audio, images and video. Its commercial applications range from copyright protection to digital rights management. The success of a digital watermarking technology depends heavily on its robustness to withstand attacks that are aimed at removing or destroying the watermark from its host data. This paper provides analysis of a number of digital image watermark attacks and attempts to classify them into categories. A set of experimental results are also provided to show the effect of these attacks on watermarks produced using different watermarking techniques.

MMOG are very large distributed applications, sharing very large states, and supporting communication between potentially thousands of player nodes. Despite the development of many solutions to define suitable architecture and communication protocols and enabling efficient deployment of these types of applications, many issues remain. In this paper, we present a new framework to build more dynamic and scalable MMOG systems. The work aims to expand upon Homura and Net Homura frameworks, with a focus towards developing a unified deployment and networking system for the deployment and execution of both P2P and Client-Server based games, which can be analysed within a real-world context. The research will build upon the most recent investigations into algorithms and techniques that are central for the production of scalable, massively multiplayer online game applications capable of consistent, responsive game play in low-bandwidth environments and determine how these methods can applied and tested within the context of the Net Homura framework.

The operation of a network of sensing devices on a global scale requires an architecture to support efficient node registration and querying across billions, if not trillions of nodes. Whilst our work to date has concentrated on the development of a worldwide sensor Web framework, a global data collection network architecture could also be applied to any effort involving data retrieval from geographically identifiable nodes. The paper presents a new network architecture, overlaid onto the fabric of the Internet, to support the efficient registration and querying of geographically based nodes on a global scale.

It is important to have continuous connectivity in a wireless sensor network after it is deployed in a hostile environment. However, such networks are constrained by the low user-to-node ratio, limited energy and bandwidth resources, entities that are usually mobile, networks without fixed infrastructure and frequent failure due to problems of energy, vulnerability to attack, etc. To address these difficulties, there is a need for wireless sensor networks to be self-organizing and self-configuring so as to improve performance, increase energy efficiency, save resources and reduce data transmission. In this paper, we present a method for monitoring, maintaining and repairing the communication network of a dynamic mobile wireless sensor network, so that network connectivity is continuously available and provides fault tolerance. Specifically, we propose an algorithm for the detection and surveillance of articulation points in graph connectivity, including an algorithm for network auto-organization in the event that this occurs.

Technology plays an important role in both primary and secondary healthcare. With widespread use of mobile devices and ubiquitous communications, new and novel platforms are emerging to administer care. Ordinary and everyday appliances used in the home are becoming integral components within these platforms and this could potentially revolutionise how health related information is monitored, accessed and used to administer better treatments. Despite the many challenges that exist, such platforms will allow for better exploitation of networked devices to provide benefits to patients with conditions, such as arthritis and back pain. Currently these conditions are treated through physiotherapy sessions in the community, which are often costly and difficult to resource. Physiotherapists alternate between patients. This means that assessments are sporadic and subjective. This paper aims to address these limitations using a system to implement body area and sensor networks within the home with data management functions for collecting and storing motion data. This data can be accessed via the home or remotely in one or more medical facilities. Using this data, quantitative assessments are performed and used to measure the patient's progress. A case study is presented that successfully illustrates tour approach.

One of the exigent problems in wireless sensor networks is the recognition of network boundary and the detection of holes within the network. In this paper, we propose an algorithm in which every node in the network self-detects whether it is a boundary node or an inner node by utilizing the available connectivity information and making no assumptions about the location awareness. The algorithm is efficient than existing schemes in terms of accuracy and energy consumption. It does not need high degree of connectivity as compare to other existing schemes. The simulation results prove the efficiency and accuracy of our algorithm.

There is undoubtedly an increase in the number of consumer appliances that are enjoying networking capabilities. With data throughput increasing among devices that are renowned to be less capable than personal computers, we see an increase in the consumption of multimedia. In parallel, gaming and social networking are at the forefront of next generation entertainment systems where new and novel usage scenarios are pushing technological boundaries. Mobile devices are becoming more like computers and vice versa and television is becoming more interactive. These advances have undoubtedly provided a platform for innovation, where a natural progression would be to blur the gap between the aforementioned technologies. For example, multimedia service provided by a television could be integrated within a virtual environment and manipulated in ways not yet seen. Here we could see television rendered as 2D linear images and as 3D models of the scene itself. This will provide the user with immersive digital content that can be changed, viewed from multiple angles, and even handled. We present a new approach demonstrated using a working prototype to implement a virtual environment capable of receiving multimedia content from a networked appliances, and manipulating it in new and novel ways.

In this paper we propose to investigate the technical requirements of a vision-based interface for games control. We present and use some of the techniques which have been developed in computer vision, image processing and vision-based perceptual user interfaces. We have implemented some common image processing techniques and evaluated their potential in terms of performance and usage for game control.

Recent years have seen an exponential growth in the use of home networks, from the Internet-enabled PC to network-enabled home appliances. Ordinary and everyday appliances used in the home will increasingly become integral components of these networks. They are required to join, leave, and self-configure in accordance with their dynamic environment. New platforms and applications are needed to mediate interactions between devices to overcome the inherent problems, limitations, and costs of bespoke solutions. While combining our disparate devices to meet future needs is challenging, it will also allow for better exploitation of networked devices to provide obvious benefits to the consumer. A number of approaches and technologies that attempt to redress this issue exist; however, they are not without their own disadvantages. This paper discusses these technologies and introduces some of the novel approaches that have been proposed to address the issue of device autoconfiguration using peer-to-peer technologies. In this way, disparate devices are able to achieve self-management without user interaction. A case study is also presented to illuminate these approaches and demonstrate the applicability of our approach.

In many applications of Wireless Sensor Networks a Sink is interested in aggregated data instead of exact values from all sensors. To send aggregated data, it is also helpful to reduce the amount of data to be transmitted and thereby conserve energy. Indeed current in-network aggregation schemes are helpful to conserve energy but they are designed without considering possible security issues related to data privacy. Often we find wireless sensor networks designed with neighbouring nodes sharing keys or with decryption at aggregator nodes. In either situation the potential for aggregator nodes to be physically compromised means data privacy is at high risk. Therefore secure data aggregation is desirable where data can be aggregated without the need for decryption at aggregator nodes. Aggregation becomes especially challenging if end-to-end privacy between a source and a destination (sink or group leader) is required. In this paper we extend our Structure and Density Independent Group Based Key Management Protocol with the additional feature of secure data aggregation to provide better data privacy to every single node in a large scale Wireless Sensor Network.

In wireless sensor networks, sensor nodes are expected to gather specific information about the environment and send it to the user. The data dissemination usually involves many nodes in a multi-hop transmission from the source towards the user base station. Since sensor nodes are energy limited and may fail at any moment, this data delivery is far from secure. Therefore, it is important to design new solution to allow a robust and reliable data dissemination. In this paper we propose a node recovery scheme that exploits the network density and the broadcasting nature of the wireless medium to replace the energy depleted or the failed nodes in the communication. We evaluate this work by simulations and show that our approach improves the communication reliability and extend the routing path time.

In our previous work we proposed a service- oriented and user-centric intrusion detection system (SUIDS) for pervasive/ubiquitous computing. The inherent features of pervasive computing request an IDS to give special concerns about resource-efficiency. In this paper, we discuss the existing resource-efficient solutions used in intrusion detection systems and refine the SUIDS with new techniques. Specifically, the paper shows how a user profile is managed in a distributed pattern to reduce the communication cost; and how a hybrid metric is used to extend the network lifetime. As a result, SUIDS achieves better performance in terms of energy efficiency while keeping high detection effectiveness.

This paper provides a timely review of influential work in the area of peer-to-peer (P2P) content search. We begin with a survey of text-based P2P search mechanisms and continue with an exposition of content-based approaches followed by a discussion of future directions.

Peer-to-peer networking technologies are gaining increasing popularity for file sharing and media streaming applications. To support these set of applications, structured peer-to-peer (P2P) overlay networks may be employed to provide an overlay substrate. In structured P2P overlay networks, peer nodes, content objects and messages are often identified using a set of well defined identifications (Ids.) Objects are stored on peer nodes based on a set of predefined rules. Messages are routed towards the destination node, for example, the root node of the message Id, after an average of h routing hops. In the absence of faults, a high probability of successful message forwarding, i.e., a message is delivered correctly to the destination node, can be achieved even when a large fraction of the peer nodes crash. However, most current overlay networks are not secure. When one or more malicious nodes are presented in the overlay, they can prevent correct message delivery throughout the overlay. This paper studies attacks aimed at preventing correct message delivery in structured peer-to-peer overlays. Several different routing algorithms are analyzed to understand means to improve messaging security without significant additional cost.

The plethora of networked multimedia services and ubiquitous devices has ultimately changed the objective of networking to one that strives in enabling the provision and interaction of networked services. It is therefore necessary especially in the home environment to consider the enhancement of the way services are provided to the end user. To be able to realise such a vision, a common interworking layer needs to be adopted. This allows all the devices to use the same IP addressing domain and therefore be considered as operating on one network. That would ultimately provide a common networking layer for the applications. In doing so, the authors would enable services to interact seamlessly without the needs of provision for roaming and handover functionalities. This paper presents BlueBridge, a solution that provides seamless wireless interworking in the lower layers. The detail of the design and implementation and provide results that prove the enhanced capabilities of its functionality.

Sensors combined with latest technologies can facilitate the dream of connecting everything in our daily lives to a network of devices easily. There is need for a middleware which can interconnect wireless sensors seamlessly with minimum software and hardware requirements. Previous work is restricted because it has only concentrated on one aspect which is application specific middleware. We propose a novel framework that allows the user to register events as well as query the system directly or through storage service. In this paper we are introducing a novel idea of storing data with in the sensor network for the life time of ad hoc wireless sensor networks (WSN). Previous works have used temporary storage but we implement persistent storage that provides increased functionality. This would help in saving precious resources like battery life by only extracting processed data which means less data would be sent to the users. Storing the data with in the network serves two purposes. First, it would help in further processing of the data for example to create implicit relationships between data and second it saves energy because transmission consumes more energy. The persistent storage will not only provide data consistency at all times by having multiple synchronised copies but also the facility to add context. The copies will be synchronised by sending data at the same time to all copies within the network after adding application required context through the data adaptation service.

Current networked appliance technologies enable devices to communicate seamlessly with one another; for example, the refrigerator at your home might communicate with your mobile phone when you are visiting the supermarket to prompt you about a shortage of food. The devices can communicate with each other irrespective of their location. A great deal of work has been done in networked appliances, but most of this has been undertaken in the field of multimedia. In this paper we used networked appliance technology in a home automation system, to avoid the problems associated with the delivery of packages while the homeowner is away. We use a peer-to-peer distributed gateway service to allow networked appliances to reach beyond the household boundary, thereby providing location independence. The use of the ad hoc gateway allows the utilisation of existing networked appliance services, which would not otherwise be possible. Users can interact with the postman and allow him access while they themselves are absent; functionality that would not otherwise be possible. We demonstrate the viability of our package delivery framework using case studies and a prototype implementation.

The paper presents a new clustering scheme for wireless sensor networks based on semantic properties. Unlike current clustering schemes where signal strength and neighbouring are the most used criteria in the cluster formation, in this work, semantic properties are also taken in consideration in the process of cluster formation. Nodes inside a same cluster are organized like a hyper tree where the cluster-head is the root. This hyper tree organization allows a layered data aggregation, avoids the clusterhead overload and energy dissipation, and makes the network more robust against links and nodes failures. We evaluate this work by simulations and show that our approach is more efficient and more energy conservative than other clustering schemes.

MMOG are very large distributed applications, sharing very large states, and supporting communication between potentially thousands of player nodes. Despite the development of many solutions to define suitable architecture, communication protocol and enabling efficient deployment of these types of applications, many issues remains which still require a solution. In this paper we discuss MOG deployed over a Peer-to-Peer architecture, supporting a distributed model of systems with shared state and we address issues related to scalability, interest management and communication. We identify an efficient partitioning and distribution of the shared state as an important aspect in such models and propose a hierarchical multi-level interest management algorithm which enables contextual communication between peers. Experiments have been carried out and show the performance of the approach.

In this paper we introduce the framework of a novel Service-oriented and User-centric Intrusion Detection System (SUIDS). It is proposed to protect ubiquitous computing environments like a smart home/office. Existing Intrusion Detection Systems (IDSs) fail to cope with such a highly heterogeneous and flexible environment due to their homogeneous system design and ineffective auditing mechanisms. Featuring a novel auditing mechanism and system architecture, SUIDS can effectively detect malicious activities of inside users. Specifically, the paper shows how network nodes are classified in order to accommodate different types of detection modules; how service specific knowledge and user profiles are used to audit users' activities and protect various networked appliances against intrusions; and how a user-centric approach is used to compose a dynamic 'defense wall' or 'quarantine' against malicious users. As a result, intrusion detection in our SUIDS is more reliable and resource-effective, with a lightweight, adaptive and heterogeneous system design. Keywords-intrusion detection; service-oriented; ubiquitous

In our previous work we proposed a service-oriented and user-centric intrusion detection system (SUIDS) for pervasive/ubiquitous computing. SUIDS meets the special requirements of pervasive computing by adopting a flexible system architecture and user-centric auditing mechanism. In this paper we present the detection methods and experiment results of SUIDS. Specifically, the paper shows how a smoothing constant is used in a user profile to represent the user's short-term behavior in real-time; and how the deviations between a user's short-term and long-term behaviors are measured by using a chi-square statistic test. As a result, SUIDS effectively achieved real-time intrusion detection in pervasive computing, with a lightweight, adaptive and heterogeneous system design

This paper provides a brief overview of recent progress of peer-to-peer (P2P) technologies for multimedia applications. We provide an overview of the technical challenges, creative solutions and results related to P2P file sharing and content search, and P2P media streaming

User demands and technological advances are moving us closer to the pervasive computing vision. The home of the future includes networked appliances that publish the functions they offer as intelligent middleware services providing flexible, intuitive and zero-maintenance mechanisms for dynamic service composition, deployment, extensibility, management and usage. Whilst much work exists relating to service-oriented frameworks, this typically relies on attribute-based service matching and discovery, which is inherently restrictive since no universally agreed service description or taxonomy is available to describe services homogeneously. Device manufacturers inadvertently use different vocabularies to describe services and therefore ambiguities between terms are likely. In this paper we address these issues and describe our networked appliance service utilisation framework (NASUF), which illustrates how services offered by networked appliances can be semantically composed to extend device capabilities and perform a plethora of data adaptation functions to automatically resolve any composition conflicts that may occur. We have developed a prototype to test NASUF and our findings show that the framework can dynamically compose services provided by networked appliances in peer-to-peer networks.

Buffer overrun vulnerabilities cause significant security problems, and have proven to be difficult to prevent. In this paper we present a novel approach to tackling the problem. Rather than concentrate on how to prevent the use of code containing buffer overrun vulnerabilities, we look at component composition techniques that can allow vulnerable code to be executed in a safe way within a composed application. We establish how this can be determined in an automated way using formal code analysis techniques and present results from the prototype system that we have developed for this purpose.

We introduce a method for harnessing the emergent behaviour of networked devices in a ubiquitous computing setting, with the aim of reducing malicious code propagation. It is not intended as a means of identifying malicious code, but rather reducing the opportunity for it to propagate once identified. At the heart of the method is a correlation between the nodes of a ubiquitous computing network and cells of a cellular automaton using the propagation of trust between devices. The use of cellular automata produces a system that is scalable, requires limited network capacity, allows for reduced resource usage and localises the security threat posed by malicious code; all essential in a ubiquitous computing environment, where we find many devices, but with restricted resources and capabilities.

A major threat to the information economy is denial-of-service (DoS) attacks. These attacks are highly prevalent despite the widespread deployment of perimeter-based countermeasures. Therefore, more effective approaches are required to counter the threat. This requirement has motivated us to propose a novel, distributed, and scalable mechanism for effective early detection and prevention of DoS attacks at the router level within a network infrastructure. This paper presents the design details of the new mechanism. Specifically, this paper shows how the mechanism combines both stateful and stateless signatures to provide early detection of DoS attacks and, therefore, protect the enterprise network. More importantly, this paper discusses how a domain-based approach to an attack response is used by the mechanism to block attack traffic. This novel approach enables the blockage of an attack to be gradually propagated only through affected domains toward the attack sources. As a result, the attack is eventually confined within its source domains, thus avoiding wasteful attack traffic overloading the network infrastructure. This approach also provides a natural way of tracing back the attack sources, without requiring the use of specific trace-back techniques and additional resources for their implementation.

This paper presents the distributed denial-of-service detection mechanism (DiDDeM) system for early detection of denial-of-service attacks. The design requirements of the system are posited to demonstrate the requirements for an early detection system. An overview of the system is presented to show how these requirements are met. DiDDeM provides a two-tier detection approach. First, pre-filters (PFs) filter traffic for possible attacks. This is achieved through the application of both stateful and stateless signatures utilising routing congestion algorithms. Second, command and control (C/sup 2/) servers provide intra- and inter-domain co-operation and response to contain an attack within the routing infrastructure. The results for stateful and stateless signature detection of TCP SYN flood attacks are presented.

The vision of ubiquitous computing presents us with unique difficulties in terms of maintaining security. Many of these relate to privacy or quality of service issues, but underpinning these is the requirement for secure execution of code. We present a novel framework for utilising a hybrid method of code analysis combined with component composition techniques. The aim has been to allow sandboxing techniques to maintain security dynamically in a ubiquitous computing environment. We argue that whilst security issues for ubiquitous computing are particularly acute, characteristics of the environment can also be harnessed advantageously to fulfil these security requirements.

The proliferation of networked appliances and the increased complexity associated with their configuration requires considerable effort from specialists and home users alike. Many of the common applications they offer and the sophisticated functions they support could be better utilised to increase performance and ensure simplicity. For example a TV, DVD player and radio have all got output speakers and they are capable of producing sound, but there is no common framework to harness these functionalities. In this paper we propose a framework that enables implicit functionalities in a home appliances network. In this network, home appliances are structured around a central service integration controller (SIC), which integrates the sen ices they offer and coordinates the communications between all service-enabled appliances, independent of the protocol type being used. Implicit functionalities can be formed based on the SIC's ability to discover and dynamically compose services to form specific configurations, which are only limited by the user's imagination. The prototype we implemented uses a home entertainment theatre system as a case study and shows that this framework not only fulfils the requirements of the paper but also gives rise to a number of issues such as the service-enabled appliance architecture and macro-scale services composition and its security.

An intrusion detection systems (IDS) main purpose is to monitor a resource and notify someone in the event of a specific occurrence for an appropriate response. Based on the sources of audit data, as IDS can be classified into host-based intrusion detection system (HBIDS) or a network-based intrusion detection system (NBIDS). In this paper we focus on NBIDS and propose a novel concept in IDSs called the nethost-sensor. We describe the nethost-sensor ability to thwart end-to-end encryption, denial of services (DoS) attacks, and reduces false positives. This paper presents our experimental procedures and results in designing the nethost-sensor.

Modern high speed integrated services networks have to support applications with diverse traffic characteristics and performance requirements. One of the most interesting approaches to integrate the different types of traffic is the theory of effective bandwidth. The effective bandwidth of a time varying source is the minimum amount of bandwidth required to satisfy its QoS. In this paper, we present a new deterministic traffic model that is based upon the effective bandwidth notion. The model is derived from a worst-case analysis of the traffic on a single-node basis. It uses a simple method to evaluate the minimum resources needed to guarantee the deterministic QoS requirements of a connection. The model is thoroughly analyzed and compared to other deterministic models available on literature. It achieves accuracy, simplicity of traffic characterization and of admission tests. Moreover, it simplifies the pricing process.

Mobile ad-hoc networks are infrastructure-free highly dynamic wireless networks, where central administration or configuration by the user is impractical. This paper highlights the questions of allowing all the wireless ad hoc devices to use the same network address in a global wireless framework. It presents the paradigm of using auto-assigned, private non-internet-routable IP addresses as the basis to provide anytime, anywhere services to nomadic end users in the information space. It follows on from our work on integrating personal mobility services architectures and interoperating wireless networked appliances. Providing a multi-hop communication over a series of user's devices each acting as a multi-port MAC bridge constructs an interoperable, interworking domain allowing applications to run seamlessly in the upper layers. We discuss the case of the IEEE 802.11 protocol specification where we present working scenarios and protocols used to initialise and maintain the operation of its multi-hop communications. It is an attempt to provide a better range of services in an interoperable heterogeneous domain to offering the services from both the network side and the local environment by means of multi-hop ad-hoc MAC bridges.

The threat to organisations from network attacks is very real. Current countermeasures to denial of service (DoS) attacks rely on the perimeter model of network security. However, as the case study and analysis in this paper make apparent, the perimeter model, which relies on firewalls and intrusion detection systems, is unable to provide an effective defence against DoS attacks. Therefore, there is a need for a new approach; one that identifies an attack beyond the perimeter. We present such an approach. We achieve early detection of DoS attacks by the identification of traffic signatures which indicate that an attack is underway. As these signatures can be identified 'outside' the perimeter, appropriate measures can be taken to prevent the attack from succeeding. We use examples of DoS attacks and a case study to demonstrate the applicability of our approach.

Forthcoming network computing systems are expected to provide a wide variety of services to personal mobility users anywhere anytime in the world. Personal mobility services require an advanced architecture that integrates support protocols, mechanisms and special functionality for the dynamic reconfiguration of applications and services available in new environments when users change from one terminal to another. This paper introduces an architecture, integrated personal mobility services architecture (IPMSA), that enhances personal mobility by providing access to integrated structured and unstructured services wherever they are available in a seamless manner.

Interactive multimedia applications over multi-hop cell or packet-switched networks have strict bounds on delay, loss, and jitter. Much research has focused on how best to handle the networking issues related to supporting quality of service (QoS) contracts without compromising network efficiency, i.e. improving network utilisation, and reducing connection packet loss and late delivery. This paper describes our novel technique, network constrained smoothing, for smoothing video traffic into a server-side transmission schedule. Our approach combines QoS metrics about video connections together with network loading information in an algorithm that divides the schedule into equal-sized intervals of constant bit-rate. We evaluate performance by simulation and compare with an existing smoothing technique, optimal smoothing. We show the benefits of using network constrained smoothing to synchronise independent multimedia streams. The results show reductions in network loading at peak times and provide manageable information for routers about currently supported multimedia traffic.

Generalized processor sharing (GPS) is an idealized fluid scheduling discipline that has desirable properties for integrated services networks. It provides tight end-to-end guarantees to leaky-bucket constrained streams regardless of the behavior of other connections. It also allocates bandwidth fairly among all connections regardless of whether or not their traffic is constrained. According to their weight assignments, GPS networks are categorized into three classes: rate proportional processor sharing (RPPS), consistent relative session treatment (CRST) and arbitrary weighting. These classes achieve different degrees of complexity, stability, coupling between delay and bandwidth, and utilization gain. We present a new GPS class: the fair-rate GPS. For this class, the weights are set in proportion to both bandwidth and required delay, thus achieving higher utilization while avoiding the coupling. problem. We evaluate the new class using MPEG video traces and show that higher utilization gain can be achieved.

What is network denial of service (DoS), and why is it such a problem? This research project has sought to investigate these questions and look at the deeper questions such as can denial of service be removed, can it be detected and can network systems adequately respond to denial of service incidents should they become subjected to them? This paper describes some issues that make network denial of service a difficult security problem, and discusses some solutions that have been provided by the security research community. The paper then provides a classification of denial of service, the consumer problem and the producer problem, which forms the bulk of modern network denial of service incidents. Finally the paper proposes requirements for a framework for the management of response to network denial of service incidents, and suggests future directions that are being developed to create the framework.

MPEG compressed video is a very important traffic type in integrated service digital networks. However, it is difficult to transmit delay and loss sensitive MPEG traffic efficiently because of its variable bit rate and bursty nature. We introduce a new scheme for allocating resources in ATM networks, for the class of MPEG applications (e.g. medical services) with the most stringent quality of service requirements. The allocation scheme is carried our through two steps. First, calculating the required resources on a per-connection basis. Second a scheduling discipline for the UNI nodes is suggested. The remaining nodes use the simple FIFO discipline. The suggested scheme leads to a reduction of bandwidth requirements. Moreover it provides a policing mechanism for misbehaving users.

This paper presents a novel protocol for achieving secure and fair document exchange among multi-parties. The protocol has the following characteristics: it employs no trusted (third) party when a majority of the parties involved behave honestly; it adopts a technique for integrity and originality verification of messages without use of either asymmetric (public key) or symmetric (conventional) encryption; and it maximises the use of hash and polynomial functions. In comparison with existing protocols, this new protocol has a number of advantages such as better flexibility and reliability. The protocol is also assessed with respect to a set of requirements such as atomicity and assurance.

Third generation mobile networks aim to offer 'any service, anywhere, at any time'. Users require privacy within these systems in order to feel confident of their use. Privacy requirements (in mobile networks) are: content, location and identification privacy, and authentication. Differing from previous approaches to privacy, the network itself is considered to be an untrusted party. The paper proposes a scheme that allows the user to register with the network and remain anonymous (both location and identification). Digital mixes are used to create anonymity and authentication is achieved through a token based scheme. Finally the aspect of information leaking to authorised third parties is discussed and billing requirements are detailed which involve the use of 'coin' like tokens traded for services.