Both bibliographic data and PDF files can be accessed free until December 2008. Copyright reserved. Table of Contents Message from the IPSJ president Editorial board for 2008 Volume 4 (2008) 138-150 Fault management/traffic management A Benchmark Tool for Network I/O Management Architectures Eiji Kawai, Suguru Yamaguchi The performance of a network server is directly influenced by its network I/O management architecture, i.e., its network I/O multiplexing mechanism. Existing benchmark tools focus on the evaluation of high-level service performance of network servers that implement specific application-layer protocols or the evaluation of low-level communication performance of network paths. However, such tools are not suitable for performance evaluation of server architectures. In this study, we developed a benchmark tool for network I/O management architectures. We implemented five representative network I/O management mechanisms as modules: multi-process, multi-thread, select, poll, and epoll. This modularised implementation enabled quantitative and fair comparisons among them. Our experimental results on Linux 2.6 revealed that the select-based and poll-based servers had no performance advantage over the others and the multi-process and multi-thread servers achieved a high performance almost equal to that of the epoll-based server. 128-137 Network Quality and Control Peer-to-Peer Multimedia Streaming with Guaranteed QoS for Future Real-time Applications Mitsuo Hayasaka, Tetsuya Miki Peer-to-Peer multimedia streaming is expected to grow rapidly in the near future. Packet losses during transmission are a serious problem for streaming media as they result in degradation of the quality of service (QoS). Forward Error Correction (FEC) is a promising technique to recover the lost packets and improve the QoS of streaming media. However, FEC may degrade the QoS of all streaming due to the increased congestion caused by the FEC overhead when streaming sessions increase. Although streaming media can be categorized into live and on-demand streaming contents, conventional FEC methods apply the same FEC scheme for both contents without distinguishing them. In this paper, we clarify the effective ranges where each conventional FEC and Retransmission scheme works well. Then, we propose a novel FEC method that distinguishes two types of streaming media and is applied for on-demand streaming contents. It can overcome the adverse effect of the FEC overhead in on-demand streaming contents during media streaming and therefore reduce the packet loss due to the FEC overhead. As a result, the packet loss ratios of both live and on-demand streaming contents are improved. Moreover, it provides the QoS according to the requirements and environments of users by using layered coding of FEC. Thus, packet losses are recovered at each end host and do not affect the next-hop streaming. The numerical analyses show that our proposed method highly improves the packet loss ratio compared to the conventional method. 114-127 Network Security Design and Implementation of an Inter-Device Authentication Framework Guaranteeing Explicit Ownership Manabu Hirano, Takeshi Okuda, Suguru Yamaguchi Future networks everywhere will be connected to innumerable Internet-ready home appliances. A device accepting connections over a network must be able to verify the identity of a connecting device in order to prevent device spoofing and other malicious actions. In this paper, we propose a security mechanism for an inter-device communication. We state the importance of a distingushing and binding mechanism between a device's identity and its ownership information to realize practical inter-device authentication. In many conventional authentication systems, the relationship between the device's identity and the ownership information is not considered. Therefore, we propose a novel inter-device authentication framework guaranteeing this relationship. Our prototype implementation employs a smart card to maintain the device's identity, the ownership information and the access control rules securely. Our framework efficiently achieves secure inter-device authentication based on the device's identity, and authorization based on the ownership information related to the device. We also show how to apply our smart card system for inter-device authentication to the existing standard security protocols. 103-113 Web Intelligence Web Resource Categorization by Detecting Potential Relations Minghua Pei, Kotaro Nakayama, Takahiro Hara, Shojiro Nishio Since Semantic Web is increasing in size and variety of resources, it is difficult for users to find the information that they really need. Therefore, it is necessary to provide an efficient and precise method without explicit specification for the Web resources. In this paper, we proposed the novel approach of integrating four processes for Web resource categorization. The processes can extract both the explicit relations extracted from the ontologies in a traditional way and the potential relations inferred from existing ontologies by focusing on some new challenges such as extracting important class names, using WordNet relations and detecting the methods of describing the Web resources. We evaluated the effectiveness by applying the categorization method to a Semantic Web search system, and confirmed that our proposed method achieves a notable improvement in categorizing the valuable Web resources based on incomplete ontologies. 91-102 Information Systems for Society and Humans Exploring Factors Effecting the Continuance of Purchasing Behavior in Internet Shopping: Extrinsic Benefits and Intrinsic Benefits Kanokwan Atchariyachanvanich, Hitoshi Okada, Noboru Sonehara Previous research examined how extrinsic and intrinsic factors influence customers to shop online. Conversely, the impact of these factors on customer retention in Internet shopping has not been examined. This study is one of the few attempts to investigate the perceived benefit factors effecting customers' continuance of purchasing items through the Internet. According to an online questionnaire filled out by 1, 111 online customers to conduct a multiple regression analysis, extrinsic benefits measured in terms of time and money savings, social adjustment, and self-enhancement as well as intrinsic benefits measured in terms of pleasure and novelty as well as fashion involvement have strong effects on the continuance of purchasing. Our findings indicate that customer retention must be promoted in Internet shopping by guaranteeing not only extrinsic benefits but also intrinsic benefits. This study discusses the relevant techniques providing those benefits to customers and guidelines for future research. 79-90 Network Security d-ACTM/VT: A Distributed Virtual AC Tree Detection Method Nobutaka Kawaguchi, Hiroshi Shigeno, Ken-ichi Okada In this paper, we propose d-ACTM/VT, a network-based worm detection method that effectively detects hit-list worms using distributed virtual AC tree detection. To detect a kind of hit-list worms named Silent worms in a distributed manner, d-ACTM was proposed. d-ACTM detects the existence of worms by detecting tree structures composed of infection connections as edges. Some undetected infection connections, however, can divide the tree structures into small trees and degrade the detection performance. To address this problem, d-ACTM/VT aggregates the divided trees as a tree named Virtual AC tree in a distributed manner and utilizes the tree size for detection. Simulation result shows d-ACTM/VT reduces the number of infected hosts before detection by 20% compared to d-ACTM. 69-78 Algorithm Theory Merging String Sequences by Longest Common Prefixes Waihong Ng, Katsuhiko Kakehi We present LCP Merge, a novel merging algorithm for merging two ordered sequences of strings. LCP Merge substitutes string comparisons with integer comparisons whenever possible to reduce the number of character-wise comparisons as well as the number of key accesses by utilizing the longest common prefixes (LCP) between the strings. As one of the applications of LCP Merge, we built a string merge sort based on recursive merge sort by replacing the merging algorithm with LCP Merge and we call it LCP Merge sort. In case of sorting strings, the computational complexity of recursive merge sort tends to be greater than O(n lg n) because string comparisons are generally not constant time and depend on the properties of the strings. However, LCP Merge sort improves recursive merge sort to the extent that its computational complexity remains O(n lg n) on average. We performed a number of experiments to compare LCP Merge sort with other string sorting algorithms to evaluate its practical performance and the experimental results showed that LCP Merge sort is efficient even in the real-world. 58-68 Regular Papers Soundness of Rewriting Induction Based on an Abstract Principle Takahito Aoto Rewriting induction (Reddy, 1990) is a method to prove inductive theorems of term rewriting systems automatically. Koike and Toyama(2000) extracted an abstract principle of rewriting induction in terms of abstract reduction systems. Based on their principle, the soundness of the original rewriting induction system can be proved. It is not known, however, whether such an approach can be adapted also for more powerful rewriting induction systems. In this paper, we give a new abstract principle that extends Koike and Toyama's abstract principle. Using this principle, we show the soundness of a rewriting induction system extended with an inference rule of simplification by conjectures. Inference rules of simplification by conjectures have been used in many rewriting induction systems. Replacement of the underlying rewriting mechanism with ordered rewriting is an important refinement of rewriting induction — with this refinement, rewriting induction can handle non-orientable equations. It is shown that, based on the introduced abstract principle, a variant of our rewriting induction system based on ordered rewriting is sound, provided that its base order is ground-total. In our system based on ordered rewriting, the simplification rule extends those of the equational fragment of some major systems from the literature. 44-57 Regular Papers Automatic Construction of Program Transformation Templates Yuki Chiba, Takahito Aoto, Yoshihito Toyama Program transformation by templates (Huet and Lang, 1978)is a technique to improve the efficiency of programs. In this technique, programs are transformed according to a given program transformation template. To enhance the variety of program transformation, it is important to introduce new transformation templates. Up to our knowledge, however, few works discuss about the construction of transformation templates. Chiba, et al. (2006) proposed a framework of program transformation by template based on term rewriting and automated verification of its correctness. Based on this framework, we propose a method that automatically constructs transformation templates from similar program transformations. The key idea of our method is a second-order generalization, which is an extension of Plotkin's first-order generalization (1969). We give a second-order generalization algorithm and prove the soundness of the algorithm. We then report about an implementation of the generalization procedure and an experiment on the construction of transformation templates. 31-43 Inter-Vehicle Communication Technology A Performance Study of Inter-Vehicle Communication Protocols for Collision Warning System Niwat Thepvilojanapong, Shinji Motegi, Hiroki Horiuchi Collision Warning Systems (CWS) can help reduce the probability and severity of car accidents by providing some sort of appropriate warning to the driver through Inter-Vehicle Communication (IVC). Especially, the CWS can help avoid collision at intersections where traffic accidents are frequent (Study Group for Promotion of ASV; Traffic Bureau, 2007). A vehicle equipped with the CWS periodically broadcasts its information, and the CWS on other vehicles use the received information to alert drivers, helping them become aware of the existence of other vehicles. To avoid collision, the CWS has concrete objectives of IVC, i.e., the CWS should receive useful information accurately and in time. Many IVC protocols including our previously proposed relay control protocol (Motegi, et al., 2006) have been developed and evaluated through traditional metrics. However, instead of using such traditional metrics directly, many requirements of the intersection CWS must be considered to judge the feasibility and practicability of IVC protocols. This paper shows performance evaluation of our previous IVC protocol developed for CWS. To study the behavior of IVC protocols, we first describe a simulation methodology including performance metrics by means of reliable and timely communications. We then use such metrics to compare our IVC protocol with the flooding protocol in large-scale simulated networks. The simulation results show that our previously proposed protocol is a good candidate for real implementation because it passes all requirements of the intersection CWS. 18-30 Mobile Security New Certificate Chain Discovery Methods for Trust Establishment in Ad Hoc Networks and Their Evaluation Hisashi Mohri, Ikuya Yasuda, Yoshiaki Takata, Hiroyuki Seki In an ad hoc network, we cannot assume a trusted certificate authority and a centralized repository that are used in ordinary Public-Key Infrastructure (PKI). Hence a PKI system of the web-of-trust type in which each node can issue certificates to others in a self-organizing manner has been studied. Although this system is useful for ad hoc networks, it has the problem that for authentication a node needs to find a certificate-chain to the destination node. In this paper, we formally model a web-of-trust-type PKI system, define the certificate-chain discovery problem, and propose a new distributed algorithm and its modification that solve the problem. Furthermore, we propose a measure of communication cost, and according to the measure, we compare our algorithm with an existing method by numerical computation for large-size networks and by simulation on randomly generated unit disk graphs for moderate-size networks. The simulation results show that the communication cost of the proposed method is less than 10% of the existing method. 9-17 Contingency Management/Risk Management Anomaly Detection on Mobile Phone Based Operational Behavior Takamasa Isohara, Keisuke Takemori, Iwao Sasase Information protection schemes on mobile phones become important challenges because mobile phones have many types of private information. In general, user authentication and anomaly detection are effective to prevent attacks by illegal users. However, the user authentication can be applied only at the beginning of use and the conventional anomaly detection is not suited for mobile phones, only but computer systems. In this paper, we propose a simple and easy-to-use anomaly detection scheme on mobile phones. The scheme records the keystrokes as the mobile phone is operated, and an anomaly detection algorithm calculates a score of similarity, to detect illegal users. We implemented a prototype system on the BREW (Binary Run-time Environment for Wireless) emulator and evaluated error rates by using results from 15 testers. From experiments results, we show the proposed scheme is able to apply the anomaly detection by checking the similarity score several times. 1-8 Network Service Basics Evaluation of the Integration Effect of Content Location and Request Routing in Content Distribution Networks Hirokazu Miura, Miki Yamamoto Recently the content distribution networks (CDNs) have been highlighted as the new network paradigm which can improve latency for Web access. In CDNs, the content location strategy and request routing techniques are important technical issues. Both of them should be used in an integrated manner in general, but CDN performance applying both these technologies has not been evaluated in detail. In this paper, we investigate the effect of integration of these techniques. For request routing, we focus on a request routing technique applied active network technology, Active Anycast, which improves both network delay and server processing delay. For content distribution technology, we propose a new strategy, Popularity-Probability, whose aim corresponds with that of Active Anycast. Performance evaluation results show that integration of Active Anycast and Popularity-Probability can hold stable delay characteristics.