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Articles 6781 - 6810 of 7446

Full-Text Articles in Physical Sciences and Mathematics

A Class Of Nonlinear Stochastic Volatility Models, Jun Yu, Zhenlin Yang Jan 2006

A Class Of Nonlinear Stochastic Volatility Models, Jun Yu, Zhenlin Yang

Research Collection School Of Economics

This paper proposes a class of nonlinear stochastic volatility models based on the Box-Cox transformation which offers an alternative to the one introduced in Andersen (1994). The proposed class encompasses many parametric stochastic volatility models that have appeared in the literature, including the well known lognormal stochastic volatility model, and has an advantage in the ease with which different specifications on stochastic volatility can be tested. In addition, the functional form of transformation which induces marginal normality of volatility is obtained as a byproduct of this general way of modeling stochastic volatility. The efficient method of moments approach is used …

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The Roles Of Digital Libraries In Teaching And Learning Geography, Chew-Hung Chang, John Hedberg, Tiong-Sa Teh, Ee Peng Lim Jan 2006

The Roles Of Digital Libraries In Teaching And Learning Geography, Chew-Hung Chang, John Hedberg, Tiong-Sa Teh, Ee Peng Lim

Research Collection School Of Computing and Information Systems

Adopting a problem-centred approach helps students to learn Geography more effectively as they are able to identify and generalize about where different resources or activities are spatially located and they learn to associate certain patterns and processes with geographical changes. In an era where web-based student-centred inquiry is gaining popularity as a mode of learning Geography, the role of digital libraries as delivery trucks (in Clark’s terminology, 1983) needs to be better understood. An obvious affordance of the digital library is that it organizes information around themes for problems to be solved. This paper describes a developmental project to build …

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In-Network Join Processing For Sensor Networks, Hai Yu, Ee Peng Lim, Jun Zhang Jan 2006

In-Network Join Processing For Sensor Networks, Hai Yu, Ee Peng Lim, Jun Zhang

Research Collection School Of Computing and Information Systems

Recent advances in hardware and wireless technologies have led to sensor networks consisting of large number of sensors capable of gathering and processing data collectively. Query processing on these sensor networks has to consider various inherent constraints. While simple queries such as select and aggregate queries in wireless sensor networks have been addressed in the literature, the processing of join queries in sensor networks remains to be investigated. In this paper, we present a synopsis join strategy for evaluating join queries in sensor networks with communication efficiency. In this strategy, instead of directly joining two relations distributed in a sensor …

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Visualization For Analyzing Trajectory-Based Metaheuristic Search Algorithms, Steven Halim, Roland H. C. Yap, Hoong Chuin Lau Jan 2006

Visualization For Analyzing Trajectory-Based Metaheuristic Search Algorithms, Steven Halim, Roland H. C. Yap, Hoong Chuin Lau

Research Collection School Of Computing and Information Systems

No abstract provided.

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Efficient Mining Of Group Patterns From User Movement Data, Yida Wang, Ee Peng Lim, San-Yih Hwang Jan 2006

Efficient Mining Of Group Patterns From User Movement Data, Yida Wang, Ee Peng Lim, San-Yih Hwang

Research Collection School Of Computing and Information Systems

In this paper, we present a new approach to derive groupings of mobile users based on their movement data. We assume that the user movement data are collected by logging location data emitted from mobile devices tracking users. We formally define group pattern as a group of users that are within a distance threshold from one another for at least a minimum duration. To mine group patterns, we first propose two algorithms, namely AGP and VG-growth. In our first set of experiments, it is shown when both the number of users and logging duration are large, AGP and VG-growth are …

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Multiagent Teamwork: Hybrid Approaches, Praveen Paruchuri, Emma Bowring, Ranjit Nair, Jonathan Pearce, Nathan Schurr, Milind Tambe, Pradeep Varakantham Jan 2006

Multiagent Teamwork: Hybrid Approaches, Praveen Paruchuri, Emma Bowring, Ranjit Nair, Jonathan Pearce, Nathan Schurr, Milind Tambe, Pradeep Varakantham

Research Collection School Of Computing and Information Systems

Today within the multiagent community, we see at least four competing methods to building multiagent systems: beliefdesireintention (BDI), distributed constraint optimization (DCOP), distributed POMDPs, and auctions or game-theoretic methods. While there is exciting progress within each approach, there is a lack of cross-cutting research. This article highlights the various hybrid techniques for multiagent teamwork developed by the teamcore group. In particular, for the past decade, the TEAMCORE research group has focused on building agent teams in complex, dynamic domains. While our early work was inspired by BDI, we will present an overview of recent research that uses DCOPs and distributed …

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Monolithic Integration Of Collimating Fresnel Lens For Beam Quality Enhancement In Tapered High Power Laser Diode, F. K. Lau, Chyng Wen Tee, X. Zhao, K. A. Williams, R. V. Penty, I. H. White, M. Calligaro, M. Lecomte, O. Parillaud, N. Michel, M. Krakowski Jan 2006

Monolithic Integration Of Collimating Fresnel Lens For Beam Quality Enhancement In Tapered High Power Laser Diode, F. K. Lau, Chyng Wen Tee, X. Zhao, K. A. Williams, R. V. Penty, I. H. White, M. Calligaro, M. Lecomte, O. Parillaud, N. Michel, M. Krakowski

Research Collection Lee Kong Chian School Of Business

We demonstrate, for the first time, a monolithic integrated lens for wide aperture gain-guided tapered laser beam quality enhancement by compensating the quadratic phase curvature. The 3mm long tapered laser with an output aperture of 170μm adopted in this design consists of a gain-guided tapered section and an index-guided ridge section and operated at 980nm. The lens design is implemented by focus ion beam etching (FIBE) technique, whereby the laser diode is mounted p-side up in order to facilitate the etching process. The lens is located 600μm away from the junction of the tapered and ridge sections, and is 40μm …

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Webarc: Website Archival Using A Structured Approach, Ee Peng Lim, Maria Marissa Dec 2005

Webarc: Website Archival Using A Structured Approach, Ee Peng Lim, Maria Marissa

Research Collection School Of Computing and Information Systems

Website archival refers to the task of monitoring and storing snapshots of website(s) for future retrieval and analysis. This task is particularly important for websites that have content changing over time with older information constantly overwritten by newer one. In this paper, we propose WEBARC as a set of software tools to allow users to construct a logical structure for a website to be archived. Classifiers are trained to. determine relevant web pages and their categories, and subsequently used in website downloading. The archival schedule can be specified and executed by a scheduler. A website viewer is also developed to …

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A Framework To Learn Bayesian Network From Changing, Multiple-Source Biomedical Data, Li G., Tze-Yun Leong Dec 2005

A Framework To Learn Bayesian Network From Changing, Multiple-Source Biomedical Data, Li G., Tze-Yun Leong

Research Collection School Of Computing and Information Systems

Structure learning in Bayesian network is a big issue. Many efforts have tried to solve this problem and quite a few algorithms have been proposed. However, when we attempt to apply the existing methods to microarray data, there are three main challenges: 1) there are many variables in the data set, 2) the sample size is small, and 3) microarray data are changing from experiment to experiment and new data are available quickly. To address these three problems, we assume that the major functions of a kind of cells do not change too much in different experiments, and propose a …

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Integration Of Probabilistic Graphic Models For Decision Support, Jiang C., Poh K., Tze-Yun Leong Dec 2005

Integration Of Probabilistic Graphic Models For Decision Support, Jiang C., Poh K., Tze-Yun Leong

Research Collection School Of Computing and Information Systems

It is a frequently encountered problem that new knowledge arrived when making decisions in a dynamic world. Usually, domain experts cannot afford enough time and knowledge to effectively assess and combine both qualitative and quantitative information in these models. Existing approaches can solve only one of two tasks instead of both. We propose a four-step algorithm to integrate multiple probabilistic graphic models, which can effectively update existing models with newly acquired models. In this algorithm, the qualitative part of model integration is performed first, followed by the quantitative combination. We illustrate our method with an example of combining three models. …

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New Efficient Mds Array Codes For Raid Part Ii: Rabin-Like Codes For Tolerating Multiple (>=4) Disk Failures, Gui-Liang Feng, Robert H. Deng, Feng Bao Dec 2005

New Efficient Mds Array Codes For Raid Part Ii: Rabin-Like Codes For Tolerating Multiple (>=4) Disk Failures, Gui-Liang Feng, Robert H. Deng, Feng Bao

Research Collection School Of Computing and Information Systems

A new class of Binary Maximum Distance Separable (MDS) array codes which are based on circular permutation matrices are introduced in this paper. These array codes are used for tolerating multiple (greater than or equal to 4) disk failures in Redundant Arrays of Inexpensive Disks (RAID) architecture. The size of the information part is m \times n, where n is the number of information disks and (m+1) is a prime integer; the size of the parity-check part is m \times r, the minimum distance is r+1, and the number of parity-check disks is r. In practical applications, m can be …

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Tailored Watermarking Schemes For Authentication Of Electronic Clinical Atlases, Feng Bao, Robert H. Deng, Beng-Chin Ooi, Yanjiang Yang Dec 2005

Tailored Watermarking Schemes For Authentication Of Electronic Clinical Atlases, Feng Bao, Robert H. Deng, Beng-Chin Ooi, Yanjiang Yang

Research Collection School Of Computing and Information Systems

It is accepted that digital watermarking is quite relevant in medical imaging. However, due to the special nature of clinical practice, it is often required that watermarking not introduce irreversible distortions to medical images. The electronic clinical atlas has such a need of "lossless" watermarking. We present two tailored reversible watermarking schemes for the clinical atlas by exploiting its inherent characteristics. We have implemented the schemes and our experimental results look very promising.

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Matrix: Adaptive Middleware For Distributed Multiplayer Games, Rajesh Krishna Balan, Maria Ebling, Paul Castro, Archan Misra Dec 2005

Matrix: Adaptive Middleware For Distributed Multiplayer Games, Rajesh Krishna Balan, Maria Ebling, Paul Castro, Archan Misra

Research Collection School Of Computing and Information Systems

Building a distributed middleware infrastructure that provides the low latency required for massively multiplayer games while still maintaining consistency is non-trivial. Previous attempts have used static partitioning or client-based peer-to-peer techniques that do not scale well to a large number of players, perform poorly under dynamic workloads or hotspots, and impose significant programming burdens on game developers. We show that it is possible to build a scalable distributed system, called Matrix, that is easily usable by game developers. We show experimentally that Matrix provides good performance, especially when hotspots occur.

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Giving Users The Steering Wheel For Guiding Resource-Adaptive Systems, Joao Sousa, Rajesh Krishna Balan, Vahe Poladian, David Garlan, Mahadev Satyanarayanan Dec 2005

Giving Users The Steering Wheel For Guiding Resource-Adaptive Systems, Joao Sousa, Rajesh Krishna Balan, Vahe Poladian, David Garlan, Mahadev Satyanarayanan

Research Collection School Of Computing and Information Systems

Addressing resource variation plays an increasingly important role in engineering today's software systems. Research in resource-adaptive applications takes an important step towards addressing this problem. However, existing solutions stop short of addressing the fact that different user tasks often have specific goals of quality of service, and that such goals often entail multiple aspects of quality of service. This paper presents a framework for engineering software systems capable of adapting to resource variations in ways that are specific to the quality goals of each user task. For that, users are empowered to specify their task-specific preferences with respect to multiple …

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A Block Oriented Fingerprinting Scheme In Relational Database, Siyuan Liu, Shuhong Wang, Robert H. Deng, Weizhong Shao Dec 2005

A Block Oriented Fingerprinting Scheme In Relational Database, Siyuan Liu, Shuhong Wang, Robert H. Deng, Weizhong Shao

Research Collection School Of Computing and Information Systems

The need for protecting rights over relational data is of ever increasing concern. There have recently been some pioneering works in this area. In this paper, we propose an effective fingerprinting scheme based on the idea of block method in the area of multimedia fingerprinting. The scheme ensures that certain bit positions of the data contain specific values. The bit positions are determined by the keys known only to the owner of the data and different buyers of the database have different bit positions and different specific values for those bit positions. The detection of the fingerprint can be completed …

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Cryptanalysis Of A Forward Secure Blind Signature Scheme With Provable Security, Shuhong Wang, Feng Bao, Robert H. Deng Dec 2005

Cryptanalysis Of A Forward Secure Blind Signature Scheme With Provable Security, Shuhong Wang, Feng Bao, Robert H. Deng

Research Collection School Of Computing and Information Systems

A forward secure blind signature scheme was proposed by Duc, Cheon and Kim, in ICICS 2003. The security of the scheme was proved to be equivalent to the strong RSA assumption in the random oracle model. In this paper we present an attack to the scheme by forging valid signatures with public keys only. The attack is so efficient that forging a valid signature needs less computation than legally generating a signature, even considering only the user side. Our result implies that the security proof of the scheme must be invalid. Furthermore we point out the fault of the proof …

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An Efficient And Robust Computational Framework For Studying Lifetime And Information Capacity In Sensor Networks, Enrique J. Duarte-Melo, Mingyan Liu, Archan Misra Dec 2005

An Efficient And Robust Computational Framework For Studying Lifetime And Information Capacity In Sensor Networks, Enrique J. Duarte-Melo, Mingyan Liu, Archan Misra

Research Collection School Of Computing and Information Systems

In this paper we investigate the expected lifetime and information capacity, defined as the maximum amount of data (bits) transferred before the first sensor node death due to energy depletion, of a data-gathering wireless sensor network. We develop a fluid-flow based computational framework that extends the existing approach, which requires precise knowledge of the layout/deployment of the network, i.e., exact sensor positions. Our method, on the other hand, views a specific network deployment as a particular instance (sample path) from an underlying distribution of sensor node layouts and sensor data rates. To compute the expected information capacity under this distribution-based …

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A Generic Object-Oriented Tabu Search Framework, Hoong Chuin Lau, Xiaomin Jia, Wee Chong Wan Dec 2005

A Generic Object-Oriented Tabu Search Framework, Hoong Chuin Lau, Xiaomin Jia, Wee Chong Wan

Research Collection School Of Computing and Information Systems

Presently, most tabu search designers devise their applications without considering the potential of design and code reuse, which consequently prolong the development of subsequent applications. In this paper, we propose a software solution known as Tabu Search Framework (TSF), which is a generic C++ software framework for tabu search implementation. The framework excels in code recycling through the use of a well- designed set of generic abstract classes that clearly define their collaborative roles in the algorithm. Additionally, the framework incorporates a centralized process and control mechanism that enhances the search with intelligence. This results in a generic framework that …

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Authenticating Query Results In Data Publishing, Di Ma, Robert H. Deng, Hwee Hwa Pang, Jianying Zhou Dec 2005

Authenticating Query Results In Data Publishing, Di Ma, Robert H. Deng, Hwee Hwa Pang, Jianying Zhou

Research Collection School Of Computing and Information Systems

We propose a communication-efficient authentication scheme to authenticate query results disseminated by untrusted data publishing servers. In our scheme, signatures of multiple tuples in the result set are aggregated into one and thus the communication overhead incurred by the signature keeps constant. Next attr-MHTs (tuple based Merkle Hash Tree) are built to further reduce the communication overhead incurred by auxiliary authentication information (AAI). Besides the property of communication-efficiency, our scheme also supports dynamic SET operations (UNION, INTERSECTION) and dynamic JOIN with immunity to reordering attack.

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Sequential Aggregate Signatures Working Over Independent Homomorphic Trapdoor One-Way Permutation Domains, Huafei Zhu, Feng Bao, Robert H. Deng Dec 2005

Sequential Aggregate Signatures Working Over Independent Homomorphic Trapdoor One-Way Permutation Domains, Huafei Zhu, Feng Bao, Robert H. Deng

Research Collection School Of Computing and Information Systems

The contribution of this paper has two folds. In the first fold, we propose a generic construction of sequential aggregate signatures from families of certificated trapdoor one-way permutations. We show that our construction is provably secure in the random oracle model assuming that the underlying homomorphic permutations are trapdoor one-way. Compared to Lysyanskaya et al’s generic construction that is constructed from a trapdoor one-way permutation family working over the same domain [16], our scheme works over independent trapdoor one-way permutation domains. The flexible choice of the underlying permutation domains benefits our scheme to its applications in the real world where …

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A Grapheme To Phoneme Converter For Standard Malay, Haizhou Li, Mahani Aljunied, Boon Seong Teoh Dec 2005

A Grapheme To Phoneme Converter For Standard Malay, Haizhou Li, Mahani Aljunied, Boon Seong Teoh

Research Collection Lee Kong Chian School Of Business

This paper describes the process of creating a grapheme-to-phoneme (G2P) converter for Standard Malay (SM). A fundamental step to building TTS and ASR engines, is to build a good G2P system that can automatically generate accurate phonemic representations for words. Our goal is to generate phonemes that reflect real speech, thereby facilitating more accurate phoneme alignment with actual waveforms (obtained from voice-data collection), keeping human intervention to the minimum. Here we discuss the key areas in SM that require considerable phonemic alterations including letter elisions, consonant insertions, multiple ways of uttering a letter/diagraph – areas that any good G2P system …

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Exploiting Self-Adaptive Posture-Based Focus Estimation For Lecture Video Editing, Feng Wang, Chong-Wah Ngo, Ting-Chuen Pong Nov 2005

Exploiting Self-Adaptive Posture-Based Focus Estimation For Lecture Video Editing, Feng Wang, Chong-Wah Ngo, Ting-Chuen Pong

Research Collection School Of Computing and Information Systems

Head pose plays a special role in estimating a presenter’s focuses and actions for lecture video editing. This paper presents an efficient and robust head pose estimation algorithm to cope with the new challenges arising in the content management of lecture videos. These challenges include speed requirement, low video quality, variant presenting styles and complex settings in modern classrooms. Our algorithm is based on a robust hierarchical representation of skin color clustering and a set of pose templates that are automatically trained. Contextual information is also considered to refine pose estimation. Most importantly, we propose an online learning approach to …

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Motion-Based Approach For Bbc Rushes Structuring And Characterization, Chong-Wah Ngo, Zailiang Pan Nov 2005

Motion-Based Approach For Bbc Rushes Structuring And Characterization, Chong-Wah Ngo, Zailiang Pan

Research Collection School Of Computing and Information Systems

No abstract provided.

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Mining Ontological Knowledge From Domain-Specific Text Documents, Xing Jiang, Ah-Hwee Tan Nov 2005

Mining Ontological Knowledge From Domain-Specific Text Documents, Xing Jiang, Ah-Hwee Tan

Research Collection School Of Computing and Information Systems

Traditional text mining systems employ shallow parsing techniques and focus on concept extraction and taxonomic relation extraction. This paper presents a novel system called CRCTOL for mining rich semantic knowledge in the form of ontology from domain-specific text documents. By using a full text parsing technique and incorporating both statistical and lexico-syntactic methods, the knowledge extracted by our system is more concise and contains a richer semantics compared with alternative systems. We conduct a case study wherein CRCTOL extracts ontological knowledge, specifically key concepts and semantic relations, from a terrorism domain text collection. Quantitative evaluation, by comparing with a state-of-the-art …

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Selective Object Stabilization For Home Video Consumers, Zailiang Pan, Chong-Wah Ngo Nov 2005

Selective Object Stabilization For Home Video Consumers, Zailiang Pan, Chong-Wah Ngo

Research Collection School Of Computing and Information Systems

This paper describes a unified approach for video stabilization. The essential goal is to stabilize image sequences that consist of moving foreground objects, which appear frequently in today's home videos captured by hand-held consumer cameras. Our proposed techniques mainly, rely on the analysis of;motion content. Three major components area initialization, segmentation and stabilization. In motion initialization, we propose a novel algorithm to efficiently search for the best possible frame in a sequence to start segmentation. Our segmentation algorithm is based on Expectation-Maximization (EM) framework which provides the mechanism for simultaneous estimation of motion models and their layers of support. Based …

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Accurately Extracting Coherent Relevant Passages Using Hidden Markov Models, Jing Jiang, Chengxiang Zhai Nov 2005

Accurately Extracting Coherent Relevant Passages Using Hidden Markov Models, Jing Jiang, Chengxiang Zhai

Research Collection School Of Computing and Information Systems

In this paper, we present a principled method for accurately extracting coherent relevant passages of variable lengths using HMMs. We show that with appropriate parameter estimation, the HMM method outperforms a number of strong baseline methods on two data sets.

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A Threshold-Based Algorithm For Continuous Monitoring Of K Nearest Neighbors, Kyriakos Mouratidis, Dimitris Papadias, Spiridon Bakiras, Yufei Tao Nov 2005

A Threshold-Based Algorithm For Continuous Monitoring Of K Nearest Neighbors, Kyriakos Mouratidis, Dimitris Papadias, Spiridon Bakiras, Yufei Tao

Research Collection School Of Computing and Information Systems

Assume a set of moving objects and a central server that monitors their positions over time, while processing continuous nearest neighbor queries from geographically distributed clients. In order to always report up-to-date results, the server could constantly obtain the most recent position of all objects. However, this naïve solution requires the transmission of a large number of rapid data streams corresponding to location updates. Intuitively, current information is necessary only for objects that may influence some query result (i.e., they may be included in the nearest neighbor set of some client). Motivated by this observation, we present a threshold-based algorithm …

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Query Processing In Spatial Databases Containing Obstacles, Jun Zhang, Dimitris Papadias, Kyriakos Mouratidis, Manli Zhu Nov 2005

Query Processing In Spatial Databases Containing Obstacles, Jun Zhang, Dimitris Papadias, Kyriakos Mouratidis, Manli Zhu

Research Collection School Of Computing and Information Systems

Despite the existence of obstacles in many database applications, traditional spatial query processing assumes that points in space are directly reachable and utilizes the Euclidean distance metric. In this paper, we study spatial queries in the presence of obstacles, where the obstructed distance between two points is defined as the length of the shortest path that connects them without crossing any obstacles. We propose efficient algorithms for the most important query types, namely, range search, nearest neighbours, e-distance joins, closest pairs and distance semi-joins, assuming that both data objects and obstacles are indexed by R-trees. The effectiveness of the proposed …

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Anonymous Dos-Resistant Access Control Protocol Using Passwords For Wireless Networks, Zhiguo Wan, Robert H. Deng, Feng Bao, Akkihebbal L. Ananda Nov 2005

Anonymous Dos-Resistant Access Control Protocol Using Passwords For Wireless Networks, Zhiguo Wan, Robert H. Deng, Feng Bao, Akkihebbal L. Ananda

Research Collection School Of Computing and Information Systems

Wireless networks have gained overwhelming popularity over their wired counterpart due to their great flexibility and convenience, but access control of wireless networks has been a serious problem because of the open medium. Passwords remain the most popular way for access control as well as authentication and key exchange. But existing password-based access control protocols are not satisfactory in that they do not provide DoS-resistance or anonymity. In this paper we analyze the weaknesses of an access control protocol using passwords for wireless networks in IEEE LCN 2001, and propose a different access control protocol using passwords for wireless networks. …

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On Security Notions Of Steganographic Systems, Kisik Chang, Robert H. Deng, Feng Bao, Sangjin Lee, Hyungjun Kim Nov 2005

On Security Notions Of Steganographic Systems, Kisik Chang, Robert H. Deng, Feng Bao, Sangjin Lee, Hyungjun Kim

Research Collection School Of Computing and Information Systems

We define the notion of pseudoprocessingness to formulate chosen-input-attack, chosen-stego-attack, and key-recovery. We then construct a efficient, provable secure steganographic algorithm against chosen-input-attack and key-recovery. So far as we know, this is the first paper dealing with those security notions.

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