Faculty Profiles - FUNABIKI Nobuo

MISC - FUNABIKI Nobuo

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An implementation of anonymous IEEE802.1X authentication with user revocation

Amang Sudarsono, Toru Nakanishi, Kouhei Miki, Nobuo Funabiki

3rd Joint Workshop on Information Security (JWIS 2008) 240 - 245 2008

An Implementation of an Anonymous IEEE802.1X Authentication with User Revocation Reducing Mobile Host's Load

MIKI KOUHEI, NAKANISHI TORU, KAWASHIMA JUN, FUNABIKI NOBUO

IPSJ SIG Notes 2007 ( 126 ) 43 - 48 2007.12

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

The IEEE802.1X authentication has been used well as an authentication protocol in the Access Point for the Internet connection. There is a problem that mobile host's privacy information can be leaked to the Internet service provider in this protocol. To solve this problem, we have proposed and implemented an anonymous authentication with user revocation using the group signature. However, there is a problem of this method that mobile host's load increases in proportion to the number of moblie hosts in the system. In this paper, an anonymous IEEEd02.1X authentication with a user revocation reducing mobile host's load is implemented by using a pairing-based group signature with verifier-local revocation, and the authentication time is evaluated.

Other Link： http://id.nii.ac.jp/1001/00044396/

Throughput Measurements under Various Contention Window Sizes in Wireless Mesh Networks

KATO Hideaki, FUNABIKI Nobuo, NAKANISHI Toru

IEICE technical report 107 ( 403 ) 55 - 60 2007.12

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

As a scalable access netwok to the Internet, we have studied the Wireless Internet-access Mesh NET-work (WIMNET) that is composed of multiple access points (APs) with multihop communications. In WIMNET, the throughput shortage can be caused by interferences among communication links between APs, and the thoughput unfairness between APs can be caused by the difference on numbers of hops from APs to the gateway. As a solution to these problems, we have proposed the contention window (CW) size control method in CSMA/CA protocol, and have evaluated it through simulations. In this paper, we evaluate the effect of our proposal through throughput measurements in real environments after implementing it on a Linux-PC. Our results show that the optimal CW size is actually different depending on the number of APs in WIMNET, and there is a trade-off between the increase of the average throughput and the fairness of the throughput between APs.

An Implementation of a Privacy Enhancing SSL/TLS Protocol Based on Group Signatures

OBAYASHI Hiroki, NAKANISHI Toru, KAWASHIMA Jun, FUNABIKI Nobuo

IEICE technical report 107 ( 397 ) 79 - 84 2007.12

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

While various Web services have spread, a lot of private information leaks have been often caused by the service vendors. One method to solve this problems is the use of the anonymous authentication based on group signatures. Group signatures allow the service vendors to verify that a signature is signed by a valid user, but they cannot know who is the signer. Therefore, the anonymous authentication based on group signatures can protect user's privacy while preventing illigal access. In this paper, we implement a privacy enhancing SSL/TLS protocol based on group signatures with membership revocation that does not need the change of user's certificate, and evaluate the authentication time. In a group with 5000 members where 10% of its members are revoked, the authentication needs about 3 seconds. This result shows the practicality of this anonymous authentication protocol for a medium scale group.

A Heuristic Algorithm for Access Point Allocation in Indoor Environments for Wireless Mesh Networks

FARAG Tamer, FUNABIKI Nobuo, NAKANISHI Toru

IEICE technical report 107 ( 378 ) 55 - 60 2007.12

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

We have studied WIMNET (Wireless Internet-access Mesh NETwork) as a flexible and inexpensive large-scale access network to the Internet. 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 can become the bottleneck due to their multihop link activations. Besides, the link quality may be degraded by obstacles such as walls in indoor environments. Thus, the proper allocation of APs is essential, such that the maximum hop count between APs should be minimized while any host in the field must be covered by at least one AP. In this paper, we formulate this AP allocation problem in indoor environments for WIMNET. Then, we present its three-stage heuristic algorithm composed of the initial AP allocation, the AP allocation optimization, and the association host optimization. The effectiveness of our approach is verified through extensive simulations using our WIMNET simulator.

An Implementation of uClinux-VServer for Embedded Systems

KAWASHIMA JUN, NAKANISHI TORU, FUNABIKI NOBUO

2007 ( 121 ) 7 - 12 2007.12

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

In this paper, we report an implementation of uClinux-VServer and its evaluations. This uClinux-VServer is actually implemented by porting Linux-VServer, an OS-level virtualization system, to uClinux. uClinux can run on a CPU with no MMU (Memory Management Unit), and thus it is suitable for embedded systems. VServer offers a virtual operating platform to a machine so that application programs can be tested there while restricting the interference to the host system on the machine. The evaluation results of the implemented uClinux-VServer show the porting overhead is very small, and the performance of applications on it has no difference from the performance on the conventional uClinux.

Other Link： http://id.nii.ac.jp/1001/00033878/

A Proposal of a Routing Tree Generation Algorithm for Minimizing the Maximum Delay in Wireless Mesh Networks

UEMURA Kanako, FUNABIKI Nobuo, NAKANISHI Toru, FARAG Tamer

IEICE technical report 107 ( 261 ) 57 - 62 2007.10

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

We have studied the Wireless Internet-access Mesh NETwork (WIMET) as a scalable wireless network to access the Internet. WIMNET is composed of multiple access points (APs) that have wireless connections with each other where at least one AP performs as the gateway AP (GW-AP) to the Internet. Each host can access to the Internet through a GW-AP after multihop wireless communications between APs from its associated AP. Thus, the increases of the transmission delay at communication links around the GW-AP and the propagation delay through the routing path between an AP and a GW-AP can degrade the performance of WIMNET. In this paper, we formulate the routing tree generation problem for AP communications to minimize the maximum delay for the bottleneck solution, and propose its heuristic algorithm. We show the effectiveness of our algorithm through simulations in two instances by using the WIMNET simulator.

An Improved Node Configuration Algorithm for WDM Ring Networks

ISSHIKI Yosuke, ISOGAI Megumi, FUNABIKI Nobuo, NAKANISHI Toru

IEICE technical report 107 ( 250 ) 27 - 32 2007.10

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

Recently, the Wavelength-Division Multiplexing (WDM) technology has attracted great interests as a key technology of realizing high-speed communications by multiplexing multiple optical signals using different wavelengths into a single optical fiber. As a WDM-based ring network for the next generation platform of metropolitan area networks, we have studied the optimal design of HORNET (Hybrid Optoelectronic Ring NETwork) for the performance improvement. In fact, we have defined the node configuration problem of assigning additional transmitters and receivers to each node under their total limits and of assigning a wavelength to each receiver, such that the communication collision rate is minimized, and presented its heuristic algorithm. In this paper, we propose the improved objective function of minimizing bottleneck bandwidth and wavelength assignment algorithm based on the variable depth search. The effectiveness of our proposal is verified through simulations, where the performance is compared with the conventional method.

A short verifier-local revocation group signature scheme with backward unlinkability

Toru Nakanishi, Nobuo Funabiki

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES E90A ( 9 ) 1793 - 1802 2007.9

Language：English Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

Previously Verifier-Local Revocation (VLR) group signature schemes from bilinear maps were proposed. In VLR schemes, only verifiers are involved in the revocation of a member, while signers are not. Thus, the VLR schemes are suitable for mobile environments. Furthermore, the previously proposed schemes satisfy the important backward unlinkability. This means that even after a member is revoked, signatures produced by the member before the revocation remain anonymous. This property is needed in case of a voluntary leave of a member or in case of a key loss. However, in the previous schemes, signatures become long, due to the adopted assumption, which should be improved in order to apply the schemes to the mobile environments. In this paper an improved VLR scheme is proposed with the shorter group signatures. This is achieved by using a different assumption, DLDH assumption, and improving zero-knowledge proofs in the group signatures. The length of the proposed group signatures is reduced to about 53% of that of the previous ones.

DOI： 10.1093/ietfec/e90-a.9.1793

An Implementation of a Pairing-Based Group Signature Scheme with Verifier-Local Revocation

HIRA Yuta, KATO Hidehiro, NAKANISHI Toru, NOGAMI Yasuyuki, FUNABIKI Nobuo, MORIKAWA Yoshitaka

IEICE technical report 107 ( 209 ) 69 - 76 2007.8

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. A pairing-based group signature scheme which can make a signer sign without any revocation information and has the short length of the signature was proposed. However this scheme has a problem that the anonymity cannot be proved in case of using the twisted pairing which is known for an efficient implementation of pairing. Then, in this paper, we extend the previous scheme to have the provable anonymity in case of using twisted pairing. In addition, we efficiently implemented the extended scheme by transforming some equations and introducing parallel processing, and then we show that the extended scheme can be executed for a practical time on a server with multi-core CPU even if about 500 members are revoked.

A Proposal of An Automatic Manual Generation Method for Installing Open Source Soft Wares using Log Files

MURAKAMI Yukikazu, FUNABIKI Nobuo, TOKUNAGA Hidekazu, SHIGETA Kazuhiro

IEICE technical report 107 ( 205 ) 51 - 56 2007.8

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

An open source software (OSS) is a software whose source code is public through the Internet, so that everybody can use and modify it freely. As a result, a lot of companies, governments, and universities are now using OSS. However, the use of OSS is actually hard for beginners because OSS has few good manuals, where OSS has been developed by volunteers. In this paper, we propose a method of automatically generating a manual for installing OSS using log files at the installation process by a trained user. Our experimental results for its evaluations using the installation of Tomcat, an Web OSS, show that more people could complete the installation of this OSS by using the manual generated by the proposed method than by using the existing manual on an Web site.

Extensions of an Web-based Learning Management System "NOBASU"

OKADA Genya, FUNABIKI Nobuo, NAKANISHI Toru, AMANO Noriki

IEICE technical report 107 ( 205 ) 75 - 80 2007.8

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

In this paper, we present the two new functions, the keyword submission function and the Web quiz function, for NOBASU. NOBASU is the Web-based learning management system (LMS) that has been developed by our research group to improve educational services in our department. The keyword submission function requests students to submit three keywords in each class before and after the class from the course materials so as to encourage them to prepare and review it. These keywords are disclosed to all the students after the submission deadline so that they can refer them for self-study. The Web quiz function enables students to take short tests about contents in classes on NOBASU. The test results are automatically graded after the student submits them. The teacher can easily register a new Web quiz by uploading a CSV file that describes the questions and the answers following the newly defined format. This CSV file can be completed at any place without Internet connections. We have implemented the two functions and have applied them to one class for freshmen at Department of Communication Network Engineering in Okayama University. From the results of the questionnaire from students about their usability, we confirm that they are very effective to improve motivations and understanding of students for this class.

A Proposal of a Lecture Scene Playback System using Digital Picture-Card Show

MOURI Aki, ISSHIKI Yosuke, FUNABIKI Nobuo, NAKANISHI Toru

IEICE technical report 107 ( 155 ) 1 - 6 2007.7

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

In this paper, we propose a lecture scene playback system using the "digital picture-card show" to support the reviewing process of lectures by students. Our proposed system produces digital picture-cards by combining digital still fine images with their corresponding voices of the lecturer, and delivers them through the World-Wide Web system. We have implemented the system, and have applied it to one class for freshmen at Communication Network Department in Okayama University. From results of the questionnaire from students after using our system, we show that our system is effective to improve motivations and understanding of students for this class.

An Implementation of Embedded Linux for Remote I/O System

SHOJI Tomoya, KAWASHIMA Jun, FUNABIKI Nobuo, NAKANISHI Toru, IIJIMA Hideki, MAEDA Yasuyuki

IEICE technical report 107 ( 36 ) 73 - 76 2007.5

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

In recent years, Lin has been getting popularity as the operating system for embedded systems, due to its various software assets and robustness. Thus, we have studied the use of Linux in remote I/O systems for industries. In this paper, we present how to adopt Linux into a remote I/O system produced from M-system Ltd. and to implement device drivers so that Linux can control I/O boxes in a fixed cycle. The evaluation using our implementation shows the practicality of the remote I/O system with Linux.

A Discussion of a Design Method of Hierarchical Chordal Ring Network for Multihop WDM Networks with Mesh Topology

KITANI Tomoya, FUNABIKI Nobuo, HIGASHINO Teruo

IEICE technical report 107 ( 36 ) 7 - 12 2007.5

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

We have proposed a hierarchical logical topology called Hierarchical Chordal Ring Network (HCRN) on WDM multi-hop ring networks. HCRN achieves a smaller network diameter with a less number of wavelengths. In this paper, we propose a design method to configure HCRN on mesh networks. The problem of constructing a optical logical topology on WDM networks is an NP-hard combinatorial problem. Thus, we propose a heuristic algorithm to construct HCRN topology on mesh networks. We evaluate our algorithm by comparing the network performance indices with existing algorithms.

An Implementation of an Anonymous IEEE802.1X Authentication with User Revocation

MIKI KOUHEI, NAKANISHI TORU, KAWASHIMA JUN, FUNABIKI NOBUO

IPSJ SIG Notes 2007 ( 16 ) 129 - 134 2007.3

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

The IEEE802.1X authentication is used well as an authentication protocol in the Access Point for the Internet connection. There is a problem that mobile host's privacy information is leaked to the Internet service provider in this protocol. To solve this problem, we have proposed and implemented an anonymous authentication using the group signature. However, there is a problem that the user revocation is not considered. In this paper, an anonymous IEEE802.1X authentication with a user revocation is implemented by using a group signature with a user revocation function, and the authentication time is evaluated.

Other Link： http://id.nii.ac.jp/1001/00034159/

A WDS Clustering Problem for Wireless Infrastructure Mesh Networks

TAJIMA Shigeto, FUNABIKI Nobuo, HIGASHINO Teruo

IEICE technical report 106 ( 577 ) 323 - 328 2007.3

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

We have studied the Wireless Infrastructure Mesh NETwork(WIMNET) as a large-scale multihop wireless network. WIMNET is composed of multiple access points (APs) that have wireless connections with each other through Wireless Distribution System (WDS). Because the number of APs in a single WDS is limited due to the broadcast packet problem, the AP clustering for multiple WDS connections is necessary to construct a large-scale WIMNET. In this paper, we formulate this WDS clustering problem of APs for WIMNET and prove the NP-completeness of its decision version. Then, we present its heuristic algorithm where we evaluate our approach through simulations.

Verifier-local revocation group signature schemes with backward unlinkability from bilinear maps

Torn Nakanishi, Nobuo Funabiki

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES E90A ( 1 ) 65 - 74 2007.1

Language：English Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

An approach of membership revocation in group signatures is verifier-local revocation (VLR for short). In this approach, only verifiers are involved in the revocation mechanism, while signers have no involvement. Thus, since signers have no load, this approach is suitable for mobile environments. Although Boneh and Shacham recently proposed a VLR group signature scheme from bilinear maps, this scheme does not satisfy the backward unlikability. The backward unlinkability means that even after a member is revoked, signatures produced by the member before the revocation remain anonymous. In this paper, we propose VLR group signature schemes with the backward unlinkability from bilinear maps.

DOI： 10.1093/ietfec/e90-a.1.65

A WDS clustering algorithm for wireless mesh networks

Shigeto Tajima, Teruo Higashino, Nobuo Funabiki, Toru Nakanishi

2007 IFIP INTERNATIONAL CONFERENCE ON WIRELESS AND OPTICAL COMMUNICATIONS NETWORKS 323 - + 2007

Language：English Publisher：IEEE

The wireless mesh network has been studied as an expandable wireless access network to the Internet. This paper focuses on the network composed of only access points (APs) that has multihop wireless connections with each other through Wireless Distribution System (WDS). Because the number of APs in a single WDS cluster is limited due to transmission loads of broadcasting control packets, the proper partition of APs for multiple WDS clusters is essential for its scale-up. In this paper, we formulate this WDS clustering problem, and prove the NP-completeness of its decision version through reduction from the bin packing problem. Then, we present its two-stage heuristic algorithm where we verify the effectiveness of our approach through extensive simulations.

DOI： 10.1109/WOCN.2007.4284191

A Proposal of a Group Siganture Scheme with Membership Revocation Using Prime Numbers and Its Implementation

HAMADA Naoto, NAKAYAMA Takuya, NAKANISHI Toru, FUNABIKI Nobuo

IEICE technical report 106 ( 411 ) 47 - 54 2006.12

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

Group signature schemes with membership revocation have been intensively researched. In this paper, we propose a new group signature scheme where the computational cost for signing/verification is lower than an existing scheme without the update of signers' private keys. In the proposed scheme, a group manager issues the membership certificate with a unique prime number to every member of the group. A revocation of a membership certificate is performed by using this prime number. To show the practicality of the proposed scheme, we implemented the scheme on a PC, and measured the execution time. In a group with 1000 members, the signature signing/verification needs about 1.3 seconds. Since this time is less than half of the time that needed in the existing scheme, the practicality of the proposed scheme is sufficiently shown.

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