A rule-based component customization technique for QoS properties
Component customization technique is an important part of component-based development (CBD) process. It allows the component to be effectively adapted and reused in diverse applications. However, existing component customization techniques focus on customizing the functionality of a component. Embedded systems generally have strict quality of service (QoS) requirements such as timeliness, memory limitations, output precisions, etc. Currently, customization for the satisfaction of QoS requirements has not been widely addressed. To address the problem, we propose the concept of configurable parameter. A configurable parameter is a constant or a variable defined in a component which, when adjusted, can provide QoS trade-offs. A QoS properties reconfigurable (QoS-R) component is a software component which can be reconfigured either statically or dynamically to provide desired QoS tradeoffs. In this paper, we present our current results in developing a new, systematic code parameterization technique which focuses on identifying configurable parameters in components and converting them into QoSR components.

title: QoS analysis for component-based embedded software: Model and methodology
abstract: Component-based development (CBD) techniques have been widely used to enhance the productivity and reduce the cost for software systems development. However, applying CBD techniques to embedded software development faces additional challenges. For embedded systems, it is crucial to consider the quality of service (QoS) attributes, such as timeliness, memory limitations, output precision, and battery constraints. Frequently, multiple components implementing the same functionality with different QoS properties (measurements in terms of QoS attributes) can be used to compose a system. Also, software components may have parameters that can be configured to satisfy different QoS requirements. Composition analysis, which is used to determine the most suitable component selections and parameter settings to best satisfy the system QoS requirement, is very important in embedded software development process. In this paper, we present a model and the methodologies to facilitate composition analysis. We define QoS requirements as constraints and objectives. Composition analysis is performed based on the QoS properties and requirements to find solutions (component selections and parameter settings) that can optimize the QoS objectives while satisfying the QoS constraints. We use a multi-objective concept to model the composition analysis problem and use an evolutionary algorithm to determine the Pareto-optimal solutions efficiently.

title: A software enhancement system for embedded software development
abstract: This paper proposes a rule-based expert system model to assist developers in enhancing the quality of embedded software. The expert system supports semi-automated source code enhancements from multiple perspectives including optimization, reconfiguration to achieve quality of service (QoS) trade-offs, conformance to coding standards, etc., by defining a rule base that is composed of modularized and extensible rule sets. The rule sets are composed of re-usable rules; the rules capture the in-depth knowledge of different software experts. The expert system also adopts a technique to support automated fact generation. This allows the expert system to support processing programs developed in different programming languages

title: Code Parameterization for Satisfaction of QoS Requirements in Embedded Software
abstract: The rapid growth of embedded systems urgently requires methods of improving the development process for these systems. Component-based development (CBD) techniques have been widely studied to enhance the productivity of developing complex applications. These techniques can benefit the software development process for embedded systems as well as other application domains. However, applying CBD techniques to embedded software development faces additional challenges. For embedded systems, it is crucial to consider the QoS attributes, such as timeliness, memory limitations, output precision, battery constraints, etc. However, it is often difficult to adjust the QoS properties of a system integrated from components that do not consider QoS properties in the first place. In this paper, we present an overview of a repository-based embedded software development methodology and then focus on component parameterization techniques. The basic concept of the parameterization process is to identify configurable parameters in a component that can be parameterized to achieve QoS tradeoffs. The component is then modified to a reconfigurable one such that its configurable parameters can be adjusted to satisfy different QoS requirements for various applications or for dynamical changing execution environment. A rule base is used to assist the parameter identification process. We also develop delta file technique to facilitate component adaptation and testing tools for QoS data collection. Keywords-embedded system, component parameterization, QoS, Repository system

title: Rule-base technique for component adaptation to support QoS-based reconfiguration
abstract: Many critical application systems require reconfigurability in order to adapt under changing environment. To achieve system reconfigurability, it is possible to use adaptation mechanisms that are external to components or to use parameterized components. This paper focuses on making components reconfigurable in terms of QoS tradeoffs. We propose a new component parameterization technique which can transform individual components to reconfigurable ones such that they can support various QoS tradeoffs to achieve overall system QoS requirements. The parameterized components can be used to develop both statically and dynamically reconfigurable systems. The proposed technique is rule based, which provides flexibility and extensibility to enhance and improve the technique. A tool set has been developed based on the proposed technique to achieve semi-automated component parameterization.

title: Improving scalability of wireless network simulation with bounded inaccuracies
abstract: Discrete event network simulators have emerged as popular tools for verification and performance evaluation of wireless networks. Nevertheless, the desire to model such networks at high fidelity implies high computational costs, limiting most researchers the ability to simulate networks with thousands of nodes. Previous attempts to optimize simulation of large-scale wireless networks have not appropriately modeled accumulation of weak interference, thereby suffering inaccuracies that may be further magnified in the evaluation of upper-layer protocols. This article presents a comprehensive analysis on the effects of common optimization techniques for large-scale wireless network simulation on the overall network performance. Based on the analysis, it formulates distance limit derivation and mobility update reduction that introduce bounded inaccuracy to the radio propagation simulation. It further proposes a novel technique, Lazy Event Scheduling with Corrective Retrospection, that reduces simulation events twenty-five fold without introducing any inaccuracy at all. The experimental results show that these optimizations can substantially improve the runtime performance of an already efficient wireless network simulator, by a factor of up to 55 for wireless networks with 3200 nodes without compromising the simulation's accuracy.

title: Cryptanalysis of a Wavelet Based Watermarking Scheme
abstract: In this paper we cryptanalyze the wavelet based watermarking scheme by Wang et al, 2002. By cryptanalysis we mean the removal of the watermark using a single watermarked copy which is equivalent to cipher text only jamming attack. The watermark embedding process replaces a particular middle frequency band of the host image (in wavelet domain) with the watermark. In the scheme, the key consists of three secrets: (i) the watermark, (ii) the random filter bank used for wavelet transform and (iii) the wavelet band where the watermark is inserted. First we observe that the secret random filter bank does not provide any security since it can be replaced by any filter bank from a large class. Further, it is possible to discover the secret wavelet band used to watermark the host image. Though in cryptography the random nature of secret key provides the security, in contrary here we show that the random nature of the watermark actually helps in identifying the secret wavelet band and consequently one can remove the watermarking signal from that band to mount the successful cryptanalytic attack.

title: Protection Against Spam Using Pre-Challenges
abstract: Spam turns out to be an increasingly serious problem to email users. A number of anti-spam schemes have been proposed and deployed, but the problem has yet been well addressed. One of those schemes is challenge-response, in which a challenge is imposed on an email sender. However, such a scheme introduces new problems for the users, e.g., delay of service and denial of service attacks. In this paper, we introduce a pre-challenge scheme that avoids those problems. It assumes each user has a challenge that is defined by the user himself/herself and associated with his/her email address, in such a way that an email sender can simultaneously retrieve a new receiver’s email address and challenge before sending an email in the first contact. Some new mechanisms are employed to reach a good balance between security against spam and convenience to email users.

title: Algorithm Selectors for Providing Location Estimation Services within a Cellular Radio Network
abstract: Mobile location estimation is becoming an important value-added service for mobile phone operators. Many mobile location estimation algorithms based on the cellular radio networks have been proposed but there exists no general solution since each algorithm has its own advantage depending on specific terrain and environmental factors. In this paper, we propose and investigate three algorithm selectors, one with a LDA classifier and the other two with Bayes classifiers using either a Naive Bayes probabilistic model or a Bayes probabilistic model, to select the best mobile location estimation algorithms from our previous work in order to combine their merits, and provide a more accurate estimation for location services. We have tested these three algorithm selectors with real data taken in Hong Kong. Experiment results have shown that they are all useful in particular, and the one with a Bayes probabilistic model outperforms all other existing location algorithms among different kinds of terrains in terms of average errors

title: Some common attacks against certified email protocols and the countermeasures
abstract: Certified email is a value-added service for standard email systems, which guarantees the fairness, i.e., the intended recipient gets the mail content if and only if the mail originator receives a non-repudiation receipt showing that the message has been received by the recipient. As far as security is concerned, fairness is the most important requirements, though some other properties are also desirable in practice. Recently, a number of certified email protocols have been proposed. However, most of those schemes have more or less weaknesses and/or security flaws. In the worst case, fairness cannot be achieved since one dishonest party can mount some attacks to cheat the honest party such that the latter cannot get the expected items. In this paper, we analyze two latest certified email protocols to demonstrate some common attacks, and then propose some improvements to avoid those security problems. We further give several informal but useful guidelines to counter those common attacks in the design of certified email protocols.