Privacy aware image template matching in clouds using ambient data

Cloud computing is ideal for image storage and processing because it provides enormously scalable storage and processing resources at low cost. One of the major drawbacks of cloud computing, however, is the lack of robust mechanisms for the users to control the privacy of the data they farm out to the clouds. In this paper, we develop an image encoding scheme that enhances the privacy of image data that is outsourced to the clouds for processing. Unlike previously proposed image encryption schemes, our encoding scheme allows different forms of pixel-level image processing to take place in the clouds while the actual image is not revealed to the cloud provider. Our encoding scheme uses a chaotic map to transform the image after it is masked with an arbitrarily chosen ambient image. We use template matching as a common image processing task to demonstrate the ability of our scheme to perform computations on privacy enhanced images. A simplified prototype of the image processing system was implemented and the experimental results are presented in this paper.     

Wireless GINI: an educational platform for hosting virtual wireless networks

We describe Wireless GINI, a wireless platform for hosting virtual networks. Wireless GINI Is Not Internet (GINI) allows each virtual network to define its own topology and network configuration, while amortizing costs by sharing the physical infrastructure. The platform also creates mechanisms to readily integrate physical wireless devices into a deployed network. The platform supports a diverse combination of network elements that are all integrated into one custom Internet. The platform seamlessly integrates process‐emulated components running on the user machine, wireless mesh overlays deployed on the wireless platform, and generic wireless devices connected to the user's custom network. Wireless GINI provides a user‐friendly interface that makes the physical setup process completely transparent to the user. A centralized server is used to provide this transparency, handle user requests, and automatically provision the shared physical infrastructure. We describe the design and implementation of Wireless GINI. Moreover, we evaluate the performance of the platform and suggest several educational experiments that can be conducted on this new platform. A detailed survey of the existing toolkits and platforms and a comparison with Wireless GINI are also provided. Copyright © 2016 John Wiley & Sons, Ltd.     

A taxonomy and survey of grid resource management systems for distributed computing

The resource management system is the central component of distributed network computing systems. There have been many projects focused on network computing that have designed and implemented resource management systems with a variety of architectures and services. In this paper, an abstract model and a comprehensive taxonomy for describing resource management architectures is developed. The taxonomy is used to identify approaches followed in the implementation of existing resource management systems for very large‐scale network computing systems known as Grids. The taxonomy and the survey results are used to identify architectural approaches and issues that have not been fully explored in the research. Copyright © 2001 John Wiley & Sons, Ltd.     

Parallel Image Correlation: Case Study to Examine Trade-Offs in Algorithm-to-Machine Mappings

Performance of a parallel algorithm on a parallel machine depends not only on the time complexity of the algorithm, but also on how the underlying machine supports the fundamental operations used by the algorithm. This study analyzes various mappings of image correlation algorithms in SIMD, MIMD, and mixed-mode environments. Experiments were conducted on the Intel Paragon, MasPar MP-1, nCUBE 2, and PASM prototype. The machine features considered in this study include: modes of parallelism, communication/computation ratio, network topology and implementation, SIMD CU/PE overlap, and communication/computation overlap. Performance of an implementation can be enhanced by using algorithmic techniques that match the machine features. Some algorithmic techniques discussed here are additional communication versus redundant computation, data block transfers, and communication/computation overlap. The results presented are applicable to a large class of image processing tasks. Case studies, such as the one presented here, are a necessary step in developing software tools for mapping an application task onto a single parallel machine and for mapping the subtasks of an application task, or a set of independent application tasks, onto a heterogeneous suite of parallel machines.     

Strategies to create platforms for differentiated services from dedicated and opportunistic resources

This paper is proposing a new platform for implementing services in future service oriented architectures. The basic premise of our proposal is that by combining the large volume of uncontracted resources with small clusters of dedicated resources, we can dramatically reduce the amount of dedicated resources while the goodput provided by the overall system remains at a high level. This paper presents particular strategies for implementing this idea for a particular class of applications. We performed very detailed simulations on synthetic and real traces to evaluate the performance of the proposed strategies. Our findings on compute-intensive applications show that preemptive reallocation of resources is necessary for assured services. The proposed preemption-based scheduling heuristic can significantly improve utilization of the dedicated resources by opportunistically offloading the peak loads on uncontracted resources, while keeping the service quality virtually unaffected.     

Decentralized management of bi-modal network resources in a distributed stream processing platform

This paper presents resource management techniques for allocating communication and computational resources in a distributed stream processing platform. The platform is designed to exploit the synergy of two classes of network connections—dedicated and opportunistic. Previous studies we conducted have demonstrated the benefits of such bi-modal resource organization that combines small pools of dedicated computers with a very large pool of opportunistic computing capacities of idle computers to serve high throughput computing applications. This paper extends the idea of bi-modal resource organization into the management of communication resources. Since distributed stream processing applications demand large volume of data transmission between processing sites at a consistent rate, adequate control over the network resources is important to ensure a steady flow of processing. The system model used in this paper is a platform where stream processing servers at distributed sites are interconnected with a combination of dedicated and opportunistic communication links. Two pertinent resource allocation problems are analyzed in detail and solved using decentralized algorithms. One is mapping of the processing and the communication tasks of the stream processing workload on the processing and the communication resources of the platform. The other is the dynamic re-allocation of the communication links due to variations in the capacity of the opportunistic communication links. Overall optimization goal of the allocations is higher task throughput and better utilization of the expensive dedicated links without deviating much from the timely completion of the tasks. The algorithms are evaluated through extensive simulation with a model based on realistic observations. The results demonstrate that the algorithms are able to exploit the synergy of bi-modal communication links towards achieving the optimization goals.     

MCGS: A Modified Conjugate Gradient Squared Algorithm for Nonsymmetric Linear Systems

The conjugate gradient squared (CGS) algorithm is a Krylov subspace algorithm that can be used to obtain fast solutions for linear systems (Ax=b) with complex nonsymmetric, very large, and very sparse coefficient matrices (A). By considering electromagnetic scattering problems as examples, a study of the performance and scalability of this algorithm on two MIMD machines is presented. A modified CGS (MCGS) algorithm, where the synchronization overhead is effectively reduced by a factor of two, is proposed in this paper. This is achieved by changing the computation sequence in the CGS algorithm. Both experimental and theoretical analyses are performed to investigate the impact of this modification on the overall execution time. From the theoretical and experimental analysis it is found that CGS is faster than MCGS for smaller number of processors and MCGS outperforms CGS as the number of processors increases. Based on this observation, a set of algorithms approach is proposed, where either CGS or MGS is selected depending on the values of the dimension of the A matrix (N) and number of processors (P). The set approach provides an algorithm that is more scalable than either the CGS or MCGS algorithms. The experiments performed on a 128-processor mesh Intel Paragon and on a 16-processor IBM SP2 with multistage network indicate that MCGS is approximately 20% faster than CGS.     

A localized certificate revocation scheme for mobile ad hoc networks

The issue of certificate revocation in mobile ad hoc networks (MANETs) where there are no on-line access to trusted authorities, is a challenging problem. In wired network environments, when certificates are to be revoked, certificate authorities (CAs) add the information regarding the certificates in question to certificate revocation lists (CRLs) and post the CRLs on accessible repositories or distribute them to relevant entities. In purely ad hoc networks, there are typically no access to centralized repositories or trusted authorities; therefore the conventional method of certificate revocation is not applicable.In this paper, we present a decentralized certificate revocation scheme that allows the nodes within a MANET to revoke the certificates of malicious entities. The scheme is fully contained and it does not rely on inputs from centralized or external entities.     

Trust Brokering and Its Use for Resource Matchmaking in Public-Resource Grids

This paper presents a trust brokering system that operates in a peer-to-peer manner. The network of trust brokers operate by providing peer reviews in the form of recommendations regarding potential resource targets. One of the distinguishing features of our work is that it separately models the accuracy and honesty concepts. By separately modeling these concepts, our model is able to significantly improve the performance. We apply the trust brokering system to a resource manager to illustrate its utility in a public-resource Grid environment. The simulations performed to evaluate the trust-aware resource matchmaking strategies indicate that high levels of ‘robustness’ can be attained by considering trust while matchmaking and allocating resources.Dr Azzedin contributed towards the work in this paper while he was at University of Manitoba, Winnipeg, Canada.