Faculty Profiles - FUNABIKI Nobuo

MISC - FUNABIKI Nobuo

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Forward-Secure Group Signatures from Pairings

Toru Nakanishi, Yuta Hira, Nobuo Funabiki

PAIRING-BASED CRYPTOGRAPHY - PAIRING 2009 5671 171 - 186 2009

Language：English Publisher：SPRINGER-VERLAG BERLIN

To reduce the damage of key exposures, forward-secure group signature schemes have been first proposed by Song. In the forward-secure schemes, a secret key of a, group member is updated by a one-way function every interval and the previous secret key is erased. Thus, even if a secret key is exposed, the signatures produced by the secret keys of previous intervals remain secure. Since the previous forward-secure group signature schemes are based on the strong RSA assumption, the signatures are longer than pairing-based group signatures. In addition, the complexity of the key update or signing/verification is O(T), where T is the total number of intervals. In this paper, a forward-secure group signature scheme from pairings is proposed. The complexity of our key update and signing/verification is O(log T).

DOI： 10.1007/978-3-642-03298-1_12

A Proposal of a Web-page Layout Optimization Method for Multimodal Browsing Sizes

Nobuo Funabiki, Yosuke Isshiki, Megumi Isogai, Toru Nakanishi

ISCE: 2009 IEEE 13TH INTERNATIONAL SYMPOSIUM ON CONSUMER ELECTRONICS, VOLS 1 AND 2 449 - 453 2009

Language：English Publisher：IEEE

Recently, Web-page browsing opportunities at multimodal browsing sizes have increased due to developments of various terminals. Meanwhile, most Web pages have been designed to fit to the standard size. As a result, the screen scroll operation is necessary to access the main content at a small size, whereas the blank space becomes large at a large size. In this paper, we propose a Web-page layout optimization method for multimodal browsing sizes by focusing on the standard Web design style with the separation of the document structure description by an XHTML file and the appearance description by a CSS file. Our method automatically generates a set of CSS files fit to different sizes from the files designed for the standard size by a user. Then, it dynamically switches to the CSS file fit to the current browsing size using JavaScript. We confirm the practicality of our proposal through experiments of the Web page generation and access at various sizes.

DOI： 10.1109/ISCE.2009.5156917

A Comparative Study of Open Source Softwares for Virtualization with Streaming Server Applications

Sritrusta Sukaridhoto, Nobuo Funabiki, Toru Nakanishi, Dadet Pramadihanto

ISCE: 2009 IEEE 13TH INTERNATIONAL SYMPOSIUM ON CONSUMER ELECTRONICS, VOLS 1 AND 2 333 - + 2009

Language：English Publisher：IEEE

Currently, several streaming servers are available to provide a variety of multimedia applications such as VoD (Video-on-Demand), IP-phone, and IP-TV. As a result, the provision of multiple streaming servers on a single machine using the virtualization technology has become important in order to save the operational/management costs while enhancing the performance and the reliability of the system. In this paper, we show the performance evaluation of two :representative open source softwares for the virtualization technology, Xen and OpenVZ, in various configurations of applications on three open source streaming servers, Red5, Darwin, and VLC. Our experimental results indicate that OpenVZ provides the better performance for streaming applications with Darwin and VLC whereas Red5 can run only on Xen.

DOI： 10.1109/ISCE.2009.5156885

A Proposal of a Scalable Web Server System Using Virtual Machine Monitor "Xen"

SHOJI Tomoya, INOUE Yuuki, FUNABIKI Nobuo, NAKANISHI Toru, KAGOTANI Hiroto

IEICE technical report 108 ( 286 ) 105 - 108 2008.11

Language：Japanese Publisher：The Institute of Electronics, Information and Communication Engineers

Recently, the virtualization technology has been often used to construct servers due to the efficiency of the computer resource utilization and the easiness of the system extension. The method of composing cluster systems using the virtualized servers has also been proposed. In this paper, we propose a safe and scalable Web server system using the virtualization technology. In this system, the SSL authentication protocol is adopted to authenticate the server hosts and the encrypted data communications. Besides, the system management tool is incorporated for the simple system management by realizing the automatic update functions of the system softwares such as the operating system and the Web server. We implemented the proposed system using Puppet as the system management tool, Ruby SNMP as the system management library, and Xen as the virtualization machine monitor. The experimental result using our implementation confirms the short time for the Web server extension.

A Construction of the Smart Access Point for Practical Wireless Mesh Networks

HIRAKATA Kengo, HORIUCHI Satoshi, FUNABIKI Nobuo, NAKANISHI Toru

IEICE technical report 108 ( 286 ) 63 - 68 2008.11

Language：Japanese Publisher：The Institute of Electronics, Information and Communication Engineers

Recently, the demand for the expansion of the service area by the wireless local area network (WLAN) has become strong due to rapid deployments of WLANs. We have studied WIMNET (wireless Internet-access mesh network) as the WLAN technology of constructing the Internet access network to the large area with the low cost and the short preparation time. In WIMNET, the service area can be flexibly expanded by adding new access points (APs) that are wirelessly connected using WDS (Wireless Distribution System). In this paper, we present the smart access paint (SAP) equipped with the Web cache function, and the multiple network interfaces, in order to solve the throughput shortage problem when the size of WIMNET increases to afford a number of hosts. We construct a simple WIMNET using multiple SAPs that were implemented on mobile personal computers, and evaluate the functions in SAP through communication experiments.

A Proposal of an Efficient Forward-Secure Group Signature Scheme Using Pairing

HIRA Yuta, NAKANISHI Toru, FUNABIKI Nobuo

IEICE technical report 108 ( 284 ) 47 - 54 2008.11

Language：Japanese Publisher：The Institute of Electronics, Information and Communication Engineers

Group signature scheme is one of signature schemes which keep signer's identity information secret. To prevent a problem that an adversary who obtains valid user's secret key can forge the signature easily in conventional group signature schemes, an RSA-based group signature scheme with forward-security that means unforgeability for signatures signed before a key exposure was proposed. However, this scheme requires O(T) complexity for key up-dating or signing/verifying. Then, in this paper, we propose a pairing-based forward-secure group signature scheme with a key update of O(1) complexity and signing/verifying of O(log T) complexity, by adding a key updating based on a tree structure. We also show that the proposed scheme satisfies the forward-security.

A Proposal of an Optimal Assignment Algorithm for General Academic Subject Registrations

SHOJI Tomoya, FUJII Hiroki, UEMURA Kanako, KAWANO Hiroki, FUNABIKI Nobuo, NAKANISHI Toru

IEICE technical report 108 ( 247 ) 51 - 56 2008.10

Language：Japanese Publisher：The Institute of Electronics, Information and Communication Engineers

Currently, general academic subjects in Okayama University consist of four categories, namely, "main subjects", "individual subjects", "guidance subjects", and "foreign language subjects". Among them, for "main subjects" and "foreign language subjects" that have much freedom in choice, students are requested to submit the ranks of the subjects that they want to take in the next semester beforehand. Then, the assignment of subjects to students is processed manually using the submitted ranks. However, this assignment task is very hard because it is necessary to assign fairly several thousand students at the same time while considering the capacity of each classroom, the bias in popularity among subjects, and movements of students between two distant campuses. In this paper, we define the assignment problem of general academic subjects to students as a combinational optimization problem, and propose its heuristic algorithm composed of two stages. We implement the algorithm as a Ruby application, and verify the effectiveness using real data in our university.

Reduction of Public-Key Size in a Revocable Group Signature Scheme with Constant Costs for Signing and Verifying

FUJII Hiroki, HIRA Yuta, NAKANISHI Toru, FUNABIKI Nobuo

IEICE technical report 108 ( 207 ) 33 - 38 2008.9

Language：Japanese Publisher：The Institute of Electronics, Information and Communication Engineers

Group signature scheme is the digital signature scheme enhancing the privacy of the user. We proposed a revocable scheme where signing and verifying require only O(1) costs, while various schemes were previously proposed. However, the scheme has a problem that the public key size is O(N). In this paper, we extend the scheme to reduce the public key size into O(√N). In addition, we implement it to confirm the reduction of the size and show that the scheme works at practical execution times.

Extensions of Supporting Functions in the Learning Management System "NOBASU"

KASAI Yasuhiro, FUNABIKI Nobuo, AMANO Noriki, NAKANISHI Toru

108 ( 88 ) 45 - 50 2008.6

A Proposal of a 4-layered Software Architecture for Learning Management Systems and Its Implementation for "NOBASU"

BABA SHOTA, FUNABIKI NOBUO, AMANO NORIKI, NAKANISHI TORU

IPSJ SIG Notes 2008 ( 31 ) 55 - 60 2008.3

Language：Japanese Publisher：Information Processing Society of Japan (IPSJ)

The Learning Management System (LMS), as a platform using the World Wide Web, has been introduced for educational activities in recent years. Our research group has actually developed an original LMS named NOBASU for educational services in our department. LMS usually needs to be extended and modified to meet the changing demands in educations. In this research, we propose a 4-layered software architecture to construct LMS with the simple structure for easy developments. Through the implementation of our proposed architecture to NOBASU, we verified the effectiveness of our approach.

Other Link： http://id.nii.ac.jp/1001/00041803/

A Proposal of An Automatic Manual Generation Method for Installing Several Open Source Soft Wares Cooperation

MURAKAMI Yukikazu, FUNABIKI Nobuo, TOKUNAGA Hidekazu, SHIGETA Kazuhiro

IPSJ SIG Notes 2008 ( 31 ) 79 - 84 2008.3

Language：Japanese Publisher：Information Processing Society of Japan (IPSJ)

An open source software (OSS) is a software whose source code has been public through the Internet, so that everybody can use and modify it freely. As a result, a lot of companies, governments, and universities have now become using OSSs. However, the use of an OSS is actually hard for its beginners, because many OSSs have few good manuals, where an OSS has usually been developed by volunteers, and the installation of an OSS sometimes requires installations of several OSS packages before it. To solve this problem, we have proposed a method of automatically generating an installation manual of an OSS. In this paper, we implement the system for this method. Then, we extend our proposed method to generating the installation manual of an OSS that requires installations of other OSS packages at the same time. We conduct experiments using an OSS example requiring installations of four OSS packages to verify the usefulness of our method.

Other Link： http://id.nii.ac.jp/1001/00041807/

An Extension of the Routing Tree Algorithm for Two-Layer Wireless Mesh Networks

UEMURA Kanako, FUNABIKI Nobuo, NAKANISHI Toru, FARAG Tamer

IEICE technical report 107 ( 524 ) 329 - 334 2008.3

Language：Japanese Publisher：The Institute of Electronics, Information and Communication Engineers

Currently, we have studied the Wireless Internet-access Mesh NETwork (WIMNET) as a scalable, flexible, and low-cost access network to the Internet, using multiple access points (APs) that are connected with each other through wireless links. In WIMNET, two types of APs are actually adopted to realize the scalability and the communication bandwidth while reducing the cost. One is the expensive, note-PC based smart AP (SAP) that can use multiple channels for wireless communications and has various functions for the Internet access. Another is the inexpensive, commercial-based conventional AP (CAP) that can use only one channel. In this paper, we propose the extension to this two-layer WIMNET of our routing tree algorithm that have been proposed for the single-layer WIMNET using only SAPs. The simulation results in two instances by the WIMNET simulator show that using our extended routing tree algorithm, the throughput of the two-layer WIMNET with a small number of SAPs does not become worse than that of the single-layer one.

A Proposal of a Classification and Link Method of Lecture Scenes for Structured Learning

MOURI AKI, FUNABIKI NOBUO, NAKANISHI TORU

IPSJ SIG Notes 2008 ( 13 ) 87 - 92 2008.2

Language：Japanese Publisher：Information Processing Society of Japan (IPSJ)

We have studied the Web-based assistance system for the structured learning using five categories of keywords in university lectures. In this paper, we propose the method for classifying into five categories the lecture scenes that are generated in our Digital picture-card based LECTure scene playback system (DILBCT), and for linking these scenes related to the same keyword on the Web system. The proposed method first generates the list of the keywords for the structured learning from the keywords that have been submitted to NOBASU, our Web-based learning management system, from students for the preparation and the review of each class. Then, it extracts the keywords and their locations in the presentation slides for the lecture. Finally, for each keyword, it classifies the slides containing the same keyword into five categories, and generates the links between the corresponding lecture scenes. For evaluations, we implemented the experimental system for the proposed method by modifying DILECT, and applied it to one class for freshmen in Department of Communication Network Engineering at Okayama University. The questionnaire results from students show that our method effectively improves their understanding of this class.

Other Link： http://id.nii.ac.jp/1001/00054062/

A Two-Stage Algorithm for Access Point Allocation in Indoor Environments for Wireless Mesh Networks

Tamer Farag, Nobuo Funabiki, Toru Nakanishi, Kanako Uemura

2008 14TH ASIA-PACIFIC CONFERENCE ON COMMUNICATIONS, (APCC), VOLS 1 AND 2 261 - 265 2008

Language：English Publisher：IEEE

As a flexible, inexpensive large-scale access network to the Internet, we have studied WIMNET (Wireless Internet-access Mesh NETwork). WIMNET is composed of multiple access points (APs) as wireless routers, where each AP has multihop wireless connections with others by the wireless distribution system (WDS). In WIMNET, communications between APs and the Internet gateway can become the bottleneck due to multihop link activations. Besides, the link quality in indoor environments may be degraded by obstacles such as walls. Thus, the proper allocation of APs is essential, such that the installation cost and the maximum hop count between APs should be minimized while any host in the service area must be covered by at least one AP In this paper, we formulate this AP allocation problem in indoor environments for WIMNET, and present its two-stage heuristic algorithm composed of the initial AP allocation and the AP allocation optimization with the association host optimization. The effectiveness of our approach is verified through extensive simulations using our WIMNET simulator.(1)

A bandwidth bottleneck resolution approach to node configuration optimization in WDM ring networks

Megurni Isogai, Nobuo Funabiki, Yosuke Isshiki, Toru Nakanishi

2008 IEEE SARNOFF SYMPOSIUM 2008 ( S13.4 ) 340 - 344 2008

Language：English Publisher：IEEE

The wavelength-division multiplexing (WDM) technology has been extensively studied as a key technology to solve global information explosions. WDM multiplexes plural signal paths using different wavelengths into one optical fiber. Among WDM-based network architectures, this paper focuses on a double-ring network for a next-generation metropolitan area network (MAN). Each node is normally. equipped with two pairs of fast-tunable transmitters and wavelength-fixed receivers (TT-FR) as interface to two fibers. To enhance the network performance, additional transmitters/receivers at nodes and receiver wavelengths should be assigned optimally depending on its design requirement, so that the bandwidth bottleneck can be resolved both on nodes and fibers. This paper formulates this node configuration problem as a combinatorial optimization problem and presents its two-phase heuristic algorithm using the greedy and variable depth search (VDS) methods. Our approach is evaluated through network simulations, where the results verify the effectiveness of this joint assignment approach.

DOI： 10.1109/SARNOF.2008.4520106

A Dynamic Channel Assignment Technique for Wireless Internet-access Mesh Networks

Walaa Hassan, Nobuo Funabiki, Toru Nakanishi

2008 14TH ASIA-PACIFIC CONFERENCE ON COMMUNICATIONS, (APCC), VOLS 1 AND 2 271 - 275 2008

Language：English Publisher：IEEE

The wireless Internet-access mesh network (WIMNET) has been studied to provide a flexible, inexpensive large-scale access network to the Internet. WIMNET is composed of multiple access points (APs) as wireless routers that are communicated with each others through multihop wireless links mainly by the wireless distribution system (WDS). In WIMNET, hosts may move in the field, which can raise issues such as the quality of service, the channel interference, and the network load management. As a result, the adaptive channel assignment to the wireless links between APs to host distributions, becomes essential to improve the performance of WIMNET. In this paper, we formulate this dynamic channel assignment (DCA) problem for WIMNET, and present a DCA technique through modifications of our existing study with the newly defined decision function for the channel reassignment. The effectiveness of our approach is verified through extensive simulations using the WIMNET simulator.

A minimum-delay routing tree algorithm for access-point communications in wireless mesh networks

Nobuo Funabiki, Kanako Uemura, Toru Nakanishi, Walaa Hassan

RIVF 2008 - 2008 IEEE International Conference on Research, Innovation and Vision for the Future in Computing and Communication Technologies 2008 161 - 166 2008

Language：English

As a scalable, flexible access network to the Internet, we have studied the design optimization and the implementation of the Wireless Internet-access Mesh NETwork (WIMNET). WIMNET is composed of multiple access points (APs) that are connected with each other by wireless communications. At least one AP performs as the gateway (GW) to the Internet. Any host in the network can access to the Internet through this GW, after associating its neighbor AP and communicating with multihop wireless links between APs. The delay along the routing path degrades the performance of WIMNET. To avoid the bottleneck of communications by minimizing the maximum delay, we formulate the routing tree problem for AP communications, and prove the NP-completeness of its decision version. Then, we propose the greedy heuristic algorithm of sequentially selecting one link that minimizes the delay of the predicted tree containing the link. The effectiveness of our algorithm is verified through extensive simulations in instances with 25 APs using the WIMNET simulator. ©2008 IEEE.

DOI： 10.1109/RIVF.2008.4586349

A Proposal of an Installation Manual Generation Method for Open Source Software Using Operation Logs

Yukikazu Murakami, Nobuo Funabiki, Hidekazu Tokunaga, Kazuhiro Shigeta, Toru Nakanishi

SITIS 2008: 4TH INTERNATIONAL CONFERENCE ON SIGNAL IMAGE TECHNOLOGY AND INTERNET BASED SYSTEMS, PROCEEDINGS 547 - 554 2008

Language：English Publisher：IEEE COMPUTER SOC

An Open Source Software (OSS) is the software whose source code has been public, usually through the Internet, so that everybody can use and modify it freely. A lot of companies, governments, and universities are now using OSS technologies because of the advantages they bring. However the use of an OSS is actually hard for its beginners, because many OSSes have few good manuals, where they have usually been developed by volunteers. Besides, the installation of an OSS package sometimes requires installations of multiple OSS packages to be integrated together In this paper we propose a method of automatically generating an installation manual of an OSS package, including the one requiring the integration of multiple OSS packages. Then, we implement the proposed method for evaluations. Our experimental results in installations of OSS packages including the one requiring the integration of four packages by generated manuals verify the effectiveness of our method.

DOI： 10.1109/SITIS.2008.62

A Lecture Scene Playback System using Digital Picture-Card Show for Distance Learning

Nobuo Funabiki, Aki Mouri, Walaa Hassan, Toru Nakanishi

2008 22ND INTERNATIONAL WORKSHOPS ON ADVANCED INFORMATION NETWORKING AND APPLICATIONS, VOLS 1-3 2008 1071 - 1076 2008

Language：English Publisher：IEEE

Recently, computer-aided slide presentations have been commonly used at lectures in universities. To improve their educational quality, this paper presents an Web-based lecture scene playback system using the digital picture-card show for distance teaming. In this system, fine still images of lecture scenes containing the lecturer, the blackboard, and the screen, are periodically taken by an off-the-shell digital photo camera, and the lecturer voice is recorded into a digital file by a personal computer during a class. Then, the digital picture-card show to play back the lecture scenes is edited by selecting one image and the voice file interval corresponding to one lecture scene defined as the time span of teaching one slide page by the lecturer The picture-card show is delivered to students through the World-Wide Web system on demand. We have implemented and applied our System to one course for freshmen in our department. The system performance and the questionnaire results from students show that our system is very efficient and practical to improve understandings and motivations of students for study of this course.

DOI： 10.1109/WAINA.2008.73

Efficient revocable group signature schemes using primes

Toru Nakanishi, Nobuo Funabiki

IPSJ Journal 49 ( 9 ) 2951 - 2962 2008

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