Earticle

Security of computer systems and networks has become very significant nowadays. Introducing and using a unified framework for modeling and quantitative security evaluation (QSE) is an open problem. Th results of our study on drawbacks of the existing security assessment methodologies motivated us to use a simulation framework for model-based security evaluation. We have used discrete-event simulation (DES) and the SimEvents tool for QSE of a domain name system (DNS). First, the normal operation of the DNS is simulated. Then, an attacker is added to the model. The aim is to evaluate the instantaneous availability of DNS as an important measure of security. Finally, as a case study, DNS spoofing attack model is constructed and the availability of the attacked system is evaluated. The proposed approach can be used for other kinds of attacks and other types of systems, networks and applications. In this paper the simulation models and their results are presented.

As a practice-oriented discipline, Software Engineering is most effectively taught by using a variety of hands-on experiences. Team-based projects where students can practice their technical and soft skills are a key feature of many software engineering courses aimed to prepare students for the realities of industrial software development. This paper surveys the objectives of software development projects in undergraduate courses and summarizes four roles in which the instructor can participate in student projects: a customer, an architect, a team manager, and a mentor. The paper is concluded with case studies illustrating the nature of these roles.

As digital halftone images are widely used in the printing of books, magazines, newspapers and computer printers, the ease with which perfect copies can be made, may lead to large-scale unauthorized copying. Watermarking has been considered for many copy prevention and copyright protection applications. The hybrid watermarking system is proposed for halftone images that the watermarks embedded based on the spatial domain and frequency domain separately to enhance the robustness. For the purpose of copyright protection, the watermarks are embedded into the halftone image with visual transparency and robustness by the variety of dispersed dot order dither arrays generated by the particle swarm optimization (PSO) method achieving good robustness and image quality produce patterns for the spatial watermarks embedding system. After the binary pseudo-wavelet transform (BPWT), the second watermarks are embedded into the high-frequency components of the BPWT coefficients of the spatial domain based watermarked image that the frequency domain based watermarking is independent to the spatial domain based one. And the modified quality criterion system for halftone images is proposed by using the PSO based visual filter. The experimental results show that the hybrid watermarking algorithm is more robust for halftone images and the watermarked halftone image possesses high image quality by the PSO algorithm.

VoIP spam will become severe problem preventing from generalization of VoIP service. For the purpose of presenting multi-leveled anti-spit framework, we divided VoIP service domain into three independent domains as an outbound, an intermediary, and an inbound domain. The proposed framework enables administrator to establish anti-spit policies in each domain. In outbound domain, the framework focuses on detecting and preventing spammers. The focus in intermediary domain is to block forged SIP message using sender policy framework. The framework enables victims to directly report spam contents they received to administrator. We showed that the multi-leveled anti-spit framework is enough to mitigate spam attacks.

In this paper, two different propagation models based on different topologies of email network are proposed. By analyzing the means and the characters of email virus spreading, the function of email virus propagation is given, and the maximum time of email virus propagation before the anti-virus software is calculated. The condition in which email virus propagation stops is also proved. The relation between average node degree and power law exponent is discussed later. The models have been testified its rationality through simulation experiments.

We explore the software metrics and build a Bayesian Network Model for defect prediction. Much previous work has concentrated on how to select the software metrics that are most likely to indicate fault-proneness, based on the hypnosis that these metrics are independent. But in reality, software metric values are predicted not only correlated with fault-proneness, but also observed internal complex relationship with each other. In this paper, we build a Bayesian network model to represent the probability distribution of each factor and how they affect defects, considering strong or weak correlations are existed between individual metric attributes. We perform a comparative experimental study of effectiveness of Bayesian Network, logistic regression and Naive Bayes on a public data set from an open source software system. The result shows that our approach produces statistically significant estimations.

Many mobile applications have evolved from simple HTML pages to complex service-oriented applications hat have high maintenance cost. This high maintenance cost is due to the heterogeneity of mobile pplications, to the fast mobile evolution and to the fast-moving market which imposes short de-velopment ycles and frequent modifications. In order to control the mainten-ance cost, quantitative metrics for redicting mobile applications’ maintaina-bility must be used. This study introduces class diagram design metrics based n Conallen’s Mobile Application Extension for UML. The study will use data from an industrial mobile pplication to show the correlation between the class diagram metrics and maintenance effort measured by the number of lines of code changed.

Recently, the need for accessing information from anywhere at any time has been a driving force for a variety of mobile applications. As the number of embedded systems increases rapidly, there has been a growing demand for the use of Service Oriented Architecture (SOA) for various applications. Embedded system service offers a systematic way to classify and assess technical realizations of business processes. But embedded system has restricted range of utilizing services in computing environment and more, a mobile computer is envisioned to be equipped with more powerful capabilities, including the storage of a small database, the capacity of data processing, a narrow user input and small size of display. This paper present embedded system software testing based on SOA to overcome mobile restriction. To improve embedded system efficient we analyzing mobile application requirement, writing service specification, optimizing design, providing extended use case specification which test use case testing and testing service test case which derived from service specification.

A series of business process in which customers, suppliers , business partners cooperate one another and hare information can be frequently found in e-commerce. Wf-XML(workflow-XML) is the language defining ML-based protocol suggested for the mutual interoperability of workflow engine, as an asynchronous web ervice protocol. The paper suggests the model facilitat-ing business partners to comprehend the workflow for their interoperability and cooperation by modeling the resource model provided by Wf-XML through ML diagram in order to interoperability different workflow engines. For this, this paper defines the mapping rule to convert Wf-XML document to UML class diagram and collaboration diagram, and suggests a echnique to model each entity of Wf-XML resource model to a class diagram and the interaction between entities to a collaboration diagram.

Recently, user who uses a multimedia files demands a high capacity file via internet. However, it is difficult to guarantee QoS about providing high capacity files by internet because that has an inconstant bandwidth. For guaranteeing the QoS, CDN (Content Delivery Network) is generally used as a method of contents delivery service. Based on CDN, we propose Content Distribution and Management using Metadata (CDM) system which can provide advanced transmission and searching method. For enhancing a transmission rate, CDM system supports segment unit based transmission method that can be possible parallel transmission. Also, we propose a distribution method through substance based search. CDM system can primarily distribute the files which includes content that user wants. Information about substance of file is stored in metadata through metadata management interface, and then the information is inserted to the high capacity file itself. When user requests a high capacity file that user wants, CDM system doesn’'t transmit all of applicable contents but firstly transmits a particular part of applicable files. Therefore a proposed CDM system can guarantee QoS for user.

MANET security is becoming a challenge for researchers with the time. The lack of infrastructure gives rise to authentication problems in these networks. Most of the TTP and non-TTP based schemes seem to be impractical for being adopted in MANETs. A hybrid key-management scheme addressed these issues effectively by pre-assigned logins on offline basis and issuing certificates on its basis using 4G services. However, the scheme did not taken into account the CRL status of servers; if it is embedded the nodes need to check frequently the server’'s CRL status for authenticating any node and place external messages outside MANET which leads to overheads. We have tried to reduce them by introducing an online MANET Authority responsible for issuing certificates by considering the CRL status of servers, renewing them and key verification within MANET that has greatly reduced the external messages.

Scanning, comparing and designing of candidate siRNAs to HBV genes have been performed by searching he DNA databases and using network servers. The homology search among the RNAi targeted region on RNA sequence of HBV and human genome was done with BLAST. Three candidate siRNAs to HBV were chosen to construct three shRNA expression vectors respectively. Two complementary DNA oligonucleotides linked by 9-nucleotide loop and RNA polymerase Ⅲ terminators were designed first, and the annealed hairpin siRNA was inserted into the plasmid that carries green fluorescent protein. Then these recombinant plasmids were transformed in Escherichia Coli and detected by PCR and sequencing. Finally, the plasmids were used to transfect HeGp2 cells with liposome. The results showed the molecular weight of PCR products matched predicted size, and three siRNA plasmids were sequenced as expected sequences. The transfected cells stained with green fluorescence were also observed. Thus the shRNA expression plasmid specific for interfering HBV replication was successfully constructed. Keywords: RNAi; siRNA; HBV; bioinformatics; computer scanning.