Peter K. K. Loh

The exchanged hypercube

This paper presents the exchanged hypercube, a new interconnection network obtained by systematically removing links from a binary hypercube. It maintains several desirable properties of the binary hypercube yet with reduced interconnection complexity. We also introduce the extended binomial tree, a spanning tree of the exchanged hypercube that preserves many desirable properties of the original binomial tree. A fault-tolerant routing strategy is also proposed for the exchanged hypercube.

Performance evaluation of efficient and reliable routing protocols for fixed-power sensor networks

Fixed-power wireless sensor networks are prevalent and cost-effective. However, they face mote failures, RF interference from environmental noise and energy constraints. Routing protocols for such networks must overcome these problems to achieve reliability, energy efficiency and scalability in message delivery. Achievement of these requirements, however, poses conflicting demands. In this paper, we propose an efficient and reliable routing protocol (EAR) that achieves reliable and scalable performance with minimal compromise of energy efficiency. The routing design of EAR is based on four parameters - expected path length and a weighted combination of distance traversed, energy levels and link transmission success history, to dynamically determine and maintain the best routes. Simulation experiments of EAR with four existing protocols demonstrate that a design based on a combination of routing parameters exhibits collectively better performance than protocols based on just hop-count and energy or those using flooding.

How network topology affects dynamic loading balancing

Previous research has proposed several different load-balancing strategies and measured their performances on either a distributed system or a multiprocessor network of specific topology. The authors broadly classify all load-balancing strategies as being either static or dynamic. For certain applications, dynamic load balancing is preferable, because then the problems variable behavior more closely matches available computational resources. The authors address the performance of five dynamic load-balancing strategies: the Gradient Model strategy, the Sender-Initiated and Receiver-Initiated strategies, the Central Job Dispatcher strategy, and the Prediction-based strategy. The authors use a trace-driven simulation approach, collecting job traces from a production-distributed computer system and using them to simulate a loosely coupled multiprocessor network. This simulator enables performance comparisons across a range of network topologies, including a 2D-mesh, a 4D-hypercube, a linear array, and a composite Fibonacci cube.

Mechanisms of Polymorphic and Metamorphic Viruses

Malware has been generally accepted as one of the top security threats to computer systems around the globe. As malware evolves at a tremendous pace and demonstrates new ways to exploit, infect and victimize the computer systems of enterprises and businesses, remaining economically viable is becoming increasingly difficult. The new trends of malware development are focused on the use of complex and sophisticated code to obstruct analysis as well as spoofing contemporary anti-virus scanners. Polymorphic and metamorphic viruses use the obfuscation techniques to obstruct deep static analysis and defeat dynamic emulators. Malware may also employ metamorphism-based methods, including encryption and decryption engines, multi-packer, garbage code insertion, instruction permutation, code transformation, anti-debugging and virtual machine, registry modification and polymorphic engines. The structural mechanisms of both polymorphic and metamorphic viruses will be presented and discussed in this paper. Finally, the new complex computer viruses such as W32/Fujacks and W32/Vundo were researched as well.

Performance simulations of moving target search algorithms

The design of appropriate moving target search (MTS) algorithms for computer-generated bots poses serious challenges as they have to satisfy stringent requirements that include computation and execution efficiency. In this paper, we investigate the performance and behaviour of existing moving target search algorithms when applied to search-and-capture gaming scenarios. As part of the investigation, we also introduce a novel algorithm known as abstraction MTS. We conduct performance simulations with a game bot and moving target within randomly generated mazes of increasing sizes and reveal that abstraction MTS exhibits competitive performance even with large problem spaces.

Fuzzy Heuristic Design for Diagnosis of Web-Based Vulnerabilities

The Common Vulnerability Scoring System (CVSS) provides an open, standardized method for rating vulnerabilities. CVSS provides base-level metrics for vulnerability classification that can be used with other strategies such as Intrusion Detection Classification to form a complete diagnostic system. This emphasizes focus on defining and representing the various strategies that can be employed to provide a formal and more practical approach to vulnerabilities assessment. The various parameters that are defined have been derived from a set of five assertions and the initial fuzzy scanner metrics (The pre-defined scanner parameters). The fuzziness of the scanner metrics allows for a greater manipulation of results before a complete diagnosis can be presented. The confidence reports (1st and 2nd degree) could be used to provide information aiding the initiation of suitable steps to be taken.

The Josephus cube: a novel interconnection network

We present a novel interconnection topology, the Josephus Cube, which supports a simple routing strategy that is minimal, deadlock- and livelock-free. The topology can optimally embed linear arrays (LAs), rings, and complete binary trees of arbitrary size, as well as 2p×q meshes. It is also a supergraph of the n-cube and several of its variants and supports a degree of fault tolerance. Finally, the topology can systematically interconnect an arbitrary number of nodes and its scalability, diameter and communications performance compare favourably with those of the n-cube and its variants.

Fuzzy Classification Metrics for Scanner Assessment and Vulnerability Reporting

In information security, web application scanners detect and provide some diagnoses for specific vulnerabilities. However, scanner performance as well as the damage potential of different vulnerabilities varies. This undermines the development of effective remediation solutions and the reliable sharing of vulnerability information. This paper describes an approach based on soft computing technology for the development of metrics that are used to grade web application scanners and vulnerabilities so that scanner performance can be evaluated and confidence levels can be computed for vulnerability reports. These metrics help derive a level of assurance that will support security management decisions, enhance effective remediation efforts, and could serve as security tool design metrics.

An Energy-Aware Clustering Approach for Wireless Sensor Networks

Energy conservation is an essential and critical requirement for a wireless sensor network with battery oper-ated nodes intended for long term operations. Prior work has described different approaches to routing protocol designs that achieve energy efficiency in a wireless sensor network. Several of these works involve variations of mote-to-mote routing (flat routing) while some make use of leader nodes in clusters to perform routing (hierarchical routing). A key question then arises as to how the performance of an energy-aware, flat routing protocol compare with that of one based on hierarchical routing. This paper demonstrates a hierarchical routing protocol design that can conserve significant energy in its setup phase as well as during its steady state data dissemination phase. This paper describes the design of this protocol and evaluates its performance against existing energy-aware flat routing protocols. Simulation results show that it exhibits competitive performance against the flat routing protocols.

A fault-tolerant communications switch prototype

A fault-tolerant communications switch prototype supporting the packet switching communications paradigm has been implemented. The special feature of this switch is that it incorporates a modified version of the grouped adaptive function, found in the Inmos IMS C104 switch, which can logically group both consecutively and non-consecutively numbered links.