2024/12/07 更新

写真a

サイトウ ケンジ
斉藤 賢爾
所属
商学学術院 大学院経営管理研究科
職名
教授
学位
工学修士 ( コーネル大学 )
博士 (政策・メディア) ( 慶應義塾大学 )

経歴

  • 2004年
    -
    2005年

    慶應義塾大学 政策・メディア研究科 特別研究助手

  • 2004年
    -
    2005年

    Research Assistant, Graduate School of Media and Governance, Keio University

  • 2003年
    -
    2004年

    慶應義塾大学 環境情報学部 非常勤講師

  • 2003年
    -
    2004年

    慶應義塾大学 湘南藤沢研究支援センター 嘱託 (非常勤)

  • 2003年
    -
    2004年

    Instructor at Faculty of Environmental Information, Keio University

  • 2003年
    -
    2004年

    Research assistant at Graduate School of Media and Governance, Keio University

  • 2002年
     
     

    東京商船大学 非常勤講師

  • 2002年
     
     

    Instructor at Tokyo Shosen University

  • 1997年
    -
    2002年

    ジオワークス (株)

  • 1997年
    -
    2002年

    Geoworks, Ltd.

  • 1988年
    -
    1997年

    日立ソフトウェアエンジニアリング (株)

  • 1988年
    -
    1997年

    日立ソフトウエアエンジニアリング(株)

▼全件表示

学歴

  •  
    -
    2004年

    慶應義塾大学  

  •  
    -
    2004年

    慶應義塾大学  

  •  
    -
    1993年

    コーネル大学   計算機科学科  

  •  
    -
    1993年

    Cornell University   Department of Computer Science  

委員歴

  • 2007年
    -
     

    The First International Symposium on Data, Privacy & E-Commerce (ISDPE 2007)  プログラム委員

  • 2007年
    -
     

    First International Workshop on Sustaining Privacy in Autonomous Collaborative Environments (SPACE 2007)  プログラム委員

  • 2006年
    -
     

    The IEEE 21st International Conference on Advanced Information Networking and Applications (AINA 2007)  プログラム委員

  • 2006年
    -
     

    The Second International Conference on Availability, Reliability and Security (ARES 2007)  プログラム委員

  • 2006年
    -
     

    The Second International Workshop on Dependable and Sustainable Peer-to-Peer Systems (DAS-P2P 2007)  プログラム委員 (座長)

  • 2005年
    -
     

    First International Workshop on Privacy and Security in Agent-based Collaborative Environments  プログラム委員

  • 2005年
    -
     

    The First International Workshop on Dependable and Sustainable Peer-to-Peer Systems  プログラム委員 (座長)

  • 2005年
    -
     

    The First International Conference on Availability, Reliability and Security (ARES 2006)  プログラム委員

  • 2005年
    -
     

    First International Workshop on Privacy and Security in Agent-based Collaborative Environments  Program Committee Member

  • 2005年
    -
     

    The First International Workshop on Dependable and Sustainable Peer-to-Peer Systems  Program Committee Member (co-chair)

  • 2005年
    -
     

    The First International Conference on Availability, Reliability and Security (ARES 2006)  Program Committee Member

▼全件表示

所属学協会

  •  
     
     

    First International Workshop on Privacy and Security in Agent-based Collaborative Environments

  •  
     
     

    The First International Workshop on Dependable and Sustainable Peer-to-Peer Systems

  •  
     
     

    Reliability and Security (ARES 2006)

  •  
     
     

    The First International Conference on Availability

  •  
     
     

    Privacy & E-Commerce (ISDPE 2007)

  •  
     
     

    The First International Symposium on Data

  •  
     
     

    First International Workshop on Sustaining Privacy in Autonomous Collaborative Environments (SPACE 2007)

  •  
     
     

    The IEEE 21st International Conference on Advanced Information Networking and Applications (AINA 2007)

  •  
     
     

    Reliability and Security (ARES 2007)

  •  
     
     

    The Second International Conference on Availability

  •  
     
     

    The Second International Workshop on Dependable and Sustainable Peer-to-Peer Systems (DAS-P2P 2007)

  •  
     
     

    First International Workshop on Privacy and Security in Agent-based Collaborative Environments

  •  
     
     

    The First International Workshop on Dependable and Sustainable Peer-to-Peer Systems

  •  
     
     

    Reliability and Security (ARES 2006)

  •  
     
     

    The First International Conference on Availability

  •  
     
     

    Privacy & E-Commerce (ISDPE 2007)

  •  
     
     

    The First International Symposium on Data

  •  
     
     

    First International Workshop on Sustaining Privacy in Autonomous Collaborative Environments (SPACE 2007)

  •  
     
     

    The IEEE 21st International Conference on Advanced Information Networking and Applications (AINA 2007)

  •  
     
     

    Reliability and Security (ARES 2007)

  •  
     
     

    The Second International Conference on Availability

  •  
     
     

    The Second International Workshop on Dependable and Sustainable Peer-to-Peer Systems (DAS-P2P 2007)

▼全件表示

研究分野

  • 安全工学 / 社会システム工学 / 情報ネットワーク / 計算機システム / ソフトウェア

研究キーワード

  • 計算機科学 計算機ソフトウエア一般 計算機網

  • Computer Science Computer software in general Computer networks

 

論文

  • Lightweight selective disclosure for verifiable documents on blockchain

    Kenji Saito, Satoki Watanabe

    ICT Express    2021年09月

    DOI

  • 治水と土地の利活用におけるブロックチェーン技術の適用可能性

    斉藤,賢爾

    土地総合研究   27 ( 4 )  2019年11月  [国内誌]

  • Can We Stabilize the Price of a Cryptocurrency?: Understanding the Design of Bitcoin and Its Potential to Compete with Central Bank Money

    Mitsuru Iwamura, Yukinobu Kitamura, Tsutomu Matsumoto, Kenji Saito

    Hitotsubashi Journal of Economics   60 ( 1 ) 41 - 60  2019年06月  [査読有り]  [国内誌]

  • Digital Currency Design for Sustainable Active Debris Removal in Space

    Kenji Saito, Shinji Hatta, Toshiya Hanada

    IEEE Transactions on Computational Social Systems   6 ( 1 ) 127 - 134  2019年02月  [査読有り]

    DOI

  • How to make a digital currency on a blockchain stable

    Saito, K., Iwamura, M.

    Future Generation Computer Systems   100  2019年  [査読有り]

    DOI

  • スマートコントラクトによる土地売買を考える

    斉藤,賢爾

    土地総合研究   25 ( 3 )  2017年07月  [国内誌]

  • 衰退する貨幣経済 : FinTechは経済の意味を変える

    斉藤, 賢爾

    企業会計 = Accounting   69 ( 6 )  2017年06月

  • ブロックチェーン,分散レジャー技術と社会の未来 -空中約束固定装置のある暮らし-

    斉藤,賢爾

    情報処理   57 ( 12 ) 1210 - 1215  2016年11月

  • ビットコインというシステム

    斉藤, 賢爾

    法とコンピュータ   ( 33 )  2015年07月  [査読有り]

  • Can We Stabilize the Price of a Cryptocurrency?: Understanding the Design of Bitcoin and Its Potential to Compete with Central Bank Money

    Iwamura, Mitsuru, Kitamura, Yukinobu, Matsumoto, Tsutomu, Saito, Kenji

    SSRN Electronic Journal    2014年01月  [査読有り]

  • 現実世界の条件に適応する分散ハッシュテーブル

    斉藤, 賢爾, 高野, 祐輝

    電子情報通信学会論文誌   96 ( 6 )  2013年06月  [査読有り]

  • TEPCO Fukushima Daiichi Nuclear Disaster and Social Media: A Chronological Overview

    Kenji Saito

    International Review of Information Ethics   18  2012年  [査読有り]

  • 地球規模OSの実現に向けて - ポスト石油・石炭ピーク時代における情報ネットワーク

    斉藤, 賢爾

    電子情報通信学会技術研究報告. IN, 情報ネットワーク   110 ( 373 )  2011年01月  [査読有り]

  • The brighter side of risks in peer-to-peer barter relationships

    Kenji Saito, Eiichi Morino

    Future Generation Computer Systems   26 ( 8 ) 1300 - 1316  2010年10月  [査読有り]

     概要を見る

    Complementary currencies in the context of P2P (peer-to-peer) networks can be powerful tools for promoting exchanges and building sustainable relationships among selfish peers on the Internet. i-WAT [K. Saito, Peer-to-peer money: Free currency over the Internet, in: Proceedings of the Second International Conference on Human.Society@Internet, HSI 2003, in: Lecture Notes in Computer Science, vol. 2713, Springer-Verlag, 2003] (Internet WAT) has been proposed as such a currency based on the WAT System [watsystems.net, WATSystems home page, hypertext document. Available electronically at http://www.watsystems.net/], a polycentric, real-life complementary currency using WAT tickets as its media of exchange
    participants spontaneously issue and circulate the tickets, whose values are backed up by chains of trust, as needed. This article investigates the claim made in the past [K. Saito, E. Morino, J. Murai, Incentive- compatibility in a distributed autonomous currency system, in: Proceedings of the Fourth International Workshop on Agents and Peer-to-Peer Computing, AP2PC 2005, 2005] that the design of i-WAT is incentive-compatible as to counteraction against moral hazards. Such hazards are impeded in i-WAT because participants will have to take natural evasive actions to avoid apparent risks posed by misbehaviors of others. This effect is measured for regular tickets, whose values remain constant over time, as well as for reduction [K. Saito, E. Morino, J. Murai, Reduction over time to facilitate peer-to-peer barter relationships, IEICE Transactions on Information and Systems E89-D (1)] and multiplication [K. Saito, E. Morino, J. Murai, Multiplication over time to facilitate peer-to-peer barter relationships, in: Proceedings of the 2nd International Workshop on P2P Data Management, Security and Trust, PDMST '05, 2005] tickets, whose values are reduced or multiplied over time, respectively, by simulating some small worlds of traders in the presence of whitewashers [M. Feldman, C. Papadimitriou, J. Chuang, I. Stoica, Free-riding and whitewashing in peer-to-peer systems, in: Proceedings of the ACM SIGCOMM Workshop on Practice and Theory of Incentives in Networked Systems, 2004, pp. 228236], a kind of free-riders who strategically leave and re-join the system with new identities. The results are compared with simulations of the MCS (Mutual Credit System), the category into which many existing currencies fall. © 2010 Elsevier B.V. All rights reserved.

    DOI

  • Distributed processing language overlay GHC and its application possibilities

    Saito, K.

    Journal of the National Institute of Information and Communications Technology   55 ( 2-3 )  2008年  [査読有り]  [国内誌]

  • Incentive-Compatibility in a distributed autonomous currency system

    Kenji Saito, Eiichi Morino, Jun Murai

    Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)   4118   44 - 57  2006年  [査読有り]

     概要を見る

    Peer-to-peer complementary currencies can be powerful tools for promoting exchanges and building sustainable relationships among selfish peers on the Internet. i-WAT[1] is a proposed such currency based on the WAT System, a polycentric complementary currency using WAT tickets as its media of exchange. Participants spontaneously issue and circulate the tickets as needed, whose values are backed up by chains of trust. i-WAT implements the tickets electronically by exchanging messages signed in OpenPGP. This paper claims that the design of i-WAT is incentive-compatible as to protection against moral hazards, or threats caused by selfish peers because they may take advantage of the rules
    such hazards are defused in i-WAT if the participants react against misbehaviors of others by pursuing their own benefits. A reference implementation of i-WAT has been developed in the form of an XMPP instant messaging client. We have been putting the currency system into practical use since June 2004. © Springer-Verlag Berlin Heidelberg 2006.

    DOI

  • Multiplication over time to facilitate peer-to-peer barter relationships

    K Saito, E Morino, J Murai

    Sixteenth International Workshop on Database and Expert Systems Applications, Proceedings     785 - 789  2005年  [査読有り]

     概要を見る

    A peer-to-peer complementary currency can be a powerful tool for promoting exchanges that make use of underutilized computing resources in a trusted way. i-WAT[11] is a proposed such currency based on the WAT System[16], a polycentric complementary currency using WAT tickets as its media of exchange: participants spontaneously issue and circulate the tickets as needed, whose values are backed up by chains of trust. i-WAT implements the tickets electronically by exchanging messages signed in OpenPGP[3].
    This paper proposes an extension to the design of i-WAT to facilitate trades. In particular we propose additional,"multiplication" tickets whose values increase over time. By deferring redemption of such tickets, the participants can receive the premium realized by increased debts of the issuers. A game-theoretical analysis shows that this feature is incentive-compatible: the issuers have no reason to strategically default despite the increased debts.
    A reference implementation of i-WAT has been developed in the form of a plug-in for an XMPP[5][6] instant messaging client. We have been putting the currency system with the proposed feature into practical use.

▼全件表示

Works(作品等)

  • 地産地消 P2P ネットワーク

    2006年
    -
     

  • 慶應義塾大学「プログラミング入門 (Cricket Logo)」インターネット配信

    2005年
    -
     

  • wija/iワット ? 人間のためのネットワーク

    2005年
    -
     

  • 慶應義塾大学「プログラミング入門 (Cricket Logo)」インターネット配信

    2004年
    -
     

  • インターネットでの P2P ? P2P は悪か?

    2004年
    -
     

  • 「グーテンベルグを超えて? RFID技術の導入による書籍の未来とそのメイキング」

    2004年
    -
     

  • 「市販の書籍にタグを付けた理由」

    2004年
    -
     

  • 慶應義塾大学「プログラミング入門 (Java)」インターネット配信

    2003年
    -
     

  • ピアツーピアアーキテクチャ

    2003年
    -
     

  • 「書籍への EPC準拠タグ搭載 ? 『インターネットの不思議、探検隊!』」 (凸版印刷株式会社との共同講演)

    2003年
    -
     

  • 東京商船大学「ヒューマンインターフェース」インターネット配信

    2002年
    -
     

  • 東京商船大学「ニューメディア論」インターネット配信

    2002年
    -
     

▼全件表示

共同研究・競争的資金等の研究課題

  • トリレンマの数理的解明とそれに基づく持続可能ブロックチェーンの研究

    日本学術振興会  科学研究費助成事業

    研究期間:

    2024年04月
    -
    2029年03月
     

    首藤 一幸, 斉藤 賢爾, 坂野 遼平, 廣中 詩織

  • ブロックチェーンを持続可能にする数理的・実験的研究

    日本学術振興会  科学研究費助成事業

    研究期間:

    2021年04月
    -
    2025年03月
     

    首藤 一幸, 斉藤 賢爾, 坂野 遼平

Misc

  • 「空中文書固定装置」のある世界

    斉藤 賢爾

    現代思想    2018年05月

  • Local Production, Local Consumption Peer-to-Peer Architecture for a Dependable and Sustainable Social Infrastructure

    The Second International Workshop on Dependable and Sustainable Peer-to-Peer Systems (DAS-P2P 2007) (SAINT 2007 Workshop) IEEE    2007年

  • Local Production, Local Consumption Peer-to-Peer Architecture for a Dependable and Sustainable Social Infrastructure

    The Second International Workshop on Dependable and Sustainable Peer-to-Peer Systems (DAS-P2P 2007) (SAINT 2007 Workshop) IEEE    2007年

  • 地産地消P2Pネットワーク

    UNIXマガジン10月号    2006年

  • Fair trading of information: A proposal for the economics of peer-to-peer systems

    Kenji Saito, Eiichi Morino, Jun Murai

    FIRST INTERNATIONAL CONFERENCE ON AVAILABILITY, RELIABILITY AND SECURITY, PROCEEDINGS     764 - +  2006年

     概要を見る

    A P2P currency can be a powerful tool for promoting exchanges in a trusted way that make use of under-utilized resources both incomputer networks and in real life.
    There are three classes of resource that can be exchanged in a P2P system: atoms (ex. physical goods by way of auctions), bits, (ex. data files) and presences (ex. time slots for computing resources such as CPU, storage or bandwidth). If these are equally treated as commodities, however the economy of the system is likely to collapse, because data files can be reproduced at a negligibly small cost whereas time slots for computing resources cannot even be stockpiled for future use.
    This paper clarifies this point by simulating a small world of traders, and proposes a novel way for applying the "reduction over time" feature[14] of i-WAT[l 1], a P2P currency. In the proposed new economic order (NEO), bits are freely shared among participants, whereas their producers are supported by peers, being given freedom to issue exchange tickets whose values are reduced over time.

  • No risk is unsafe: Stimulated results on dependability of complementary currencies

    Kenji Saito, Eiichi Morino, Jun Murai

    FIRST INTERNATIONAL CONFERENCE ON AVAILABILITY, RELIABILITY AND SECURITY, PROCEEDINGS     701 - +  2006年

     概要を見る

    Efforts have been put for electronization of complementary currencies (alternative forms of monetary media) in the hope that it would reduce their operational cost. However this paper argues that the problem is more inherent in the core design of MCS[7] (Mutual Credit System), the most common form of complementary currency today. By simulating a small world of 2,500 traders, we show that growing the number of free-riders in MCS has a paradoxical effect of increasing "welfare" (a "happiness" metric) of the community. Since there is no pressure to stop the growth of the bad users, it is difficult to sustain the soundness of the system without strong interventions from the operators of the system; we need alternatives to the alternatives.
    We have proposed i-WAT[6] as an electronic descendant of the WAT System[10], a polycentric complementary currency using "WAT tickets" as its media of exchange. A simulation using the same model as above indicates that i-WAT users can sustain barter relationships even in the presence of free-riders by natural evasive actions to avoid risks.

    DOI

  • Reduction over time to facilitate peer-to-peer barter relationships

    Kenji Saito

    IEICE Transactions on Information and Systems   E89D ( 1 ) 181 - 188  2006年01月  [査読有り]   [ 国内誌 ]

     概要を見る

    A peer-to-peer complementary currency can be a powerful tool for promoting exchanges and building relationships on the Internet. i-WAT [1] is a proposed such currency based on the WAT System [2], a polycentric complementary currency using WAT tickets as its media of exchange: participants spontaneously issue and circulate the tickets as needed, whose values are backed up by chains of trust. i-WAT implements the tickets electronically by exchanging messages signed in OpenPGP [3]. This paper investigates an extension to the design of i-WAT to facilitate mutual help among peers in need. In particular, we investigate additional "reduction" tickets whose values are reduced over time. By deferring redemption of such tickets, the participants can contribute to reduce the debts of the issuers, and the issuers help participants by providing exchange media that accelerate spending. This paper describes in detail how incentive-compatibility is achieved by this extended design; we predict that the following properties will hold, which resulted from a game-theoretical analysis.
    1. Rapid circulation, or a reduction ticket will typically circulate at high speed until its effective value reaches the scheduled minimum, and
    2. Vanishment equilibrium, or the system will be most stable if the values of tickets are to be reduced down to zero.
    A reference implementation of i-WAT has been developed in the form of a plug-in for an XMPP [4], [5] instant messaging client. We have been putting the currency system into practical use, to which the proposed feature has been added.

    DOI CiNii

  • i-WAT: The Internet WAT System - An Architecture for Maintaining Trust and Facilitating Peer-to-Peer Barter Relationships

    政策・メディア研究科 学位論文    2006年

  • 特別企画 拡張可能なインスタントメッセージングプロトコル Jabber の魅力に迫る

    月刊 JavaWorld 2006年1月号    2006年

  • Fair trading of information: A proposal for the economics of peer-to-peer systems

    Kenji Saito, Eiichi Morino, Jun Murai

    FIRST INTERNATIONAL CONFERENCE ON AVAILABILITY, RELIABILITY AND SECURITY, PROCEEDINGS     764 - +  2006年

     概要を見る

    A P2P currency can be a powerful tool for promoting exchanges in a trusted way that make use of under-utilized resources both incomputer networks and in real life.
    There are three classes of resource that can be exchanged in a P2P system: atoms (ex. physical goods by way of auctions), bits, (ex. data files) and presences (ex. time slots for computing resources such as CPU, storage or bandwidth). If these are equally treated as commodities, however the economy of the system is likely to collapse, because data files can be reproduced at a negligibly small cost whereas time slots for computing resources cannot even be stockpiled for future use.
    This paper clarifies this point by simulating a small world of traders, and proposes a novel way for applying the "reduction over time" feature[14] of i-WAT[l 1], a P2P currency. In the proposed new economic order (NEO), bits are freely shared among participants, whereas their producers are supported by peers, being given freedom to issue exchange tickets whose values are reduced over time.

  • No risk is unsafe: Stimulated results on dependability of complementary currencies

    Kenji Saito, Eiichi Morino, Jun Murai

    FIRST INTERNATIONAL CONFERENCE ON AVAILABILITY, RELIABILITY AND SECURITY, PROCEEDINGS     701 - +  2006年

     概要を見る

    Efforts have been put for electronization of complementary currencies (alternative forms of monetary media) in the hope that it would reduce their operational cost. However this paper argues that the problem is more inherent in the core design of MCS[7] (Mutual Credit System), the most common form of complementary currency today. By simulating a small world of 2,500 traders, we show that growing the number of free-riders in MCS has a paradoxical effect of increasing "welfare" (a "happiness" metric) of the community. Since there is no pressure to stop the growth of the bad users, it is difficult to sustain the soundness of the system without strong interventions from the operators of the system; we need alternatives to the alternatives.
    We have proposed i-WAT[6] as an electronic descendant of the WAT System[10], a polycentric complementary currency using "WAT tickets" as its media of exchange. A simulation using the same model as above indicates that i-WAT users can sustain barter relationships even in the presence of free-riders by natural evasive actions to avoid risks.

    DOI

  • Reduction over time to facilitate peer-to-peer barter relationships

    Saito, K., Morino, E., Murai, J.

    IEICE Transactions on Information and Systems   E89-D ( 1 ) 181 - 188  2006年  [査読有り]

     概要を見る

    A peer-to-peer complementary currency can be a powerful tool for promoting exchanges and building relationships on the Internet. i-WAT [1] is a proposed such currency based on the WAT System [2], a polycentric complementary currency using WAT tickets as its media of exchange: participants spontaneously issue and circulate the tickets as needed, whose values are backed up by chains of trust. i-WAT implements the tickets electronically by exchanging messages signed in OpenPGP [3]. This paper investigates an extension to the design of i-WAT to facilitate mutual help among peers in need. In particular, we investigate additional "reduction" tickets whose values are reduced over time. By deferring redemption of such tickets, the participants can contribute to reduce the debts of the issuers, and the issuers help participants by providing exchange media that accelerate spending. This paper describes in detail how incentive-compatibility is achieved by this extended design; we predict that the following properties will hold, which resulted from a game-theoretical analysis.
    1. Rapid circulation, or a reduction ticket will typically circulate at high speed until its effective value reaches the scheduled minimum, and
    2. Vanishment equilibrium, or the system will be most stable if the values of tickets are to be reduced down to zero.
    A reference implementation of i-WAT has been developed in the form of a plug-in for an XMPP [4], [5] instant messaging client. We have been putting the currency system into practical use, to which the proposed feature has been added.

    DOI CiNii

  • i-WAT: The Internet WAT System - An Architecture for Maintaining Trust and Facilitating Peer-to-Peer Barter Relationships

       2006年

  • WOT for WAT: Spinning the web of trust for peer-to-peer barter relationships

    Kenji Saito

    IEICE Transactions on Communications   E88-B ( 4 ) 1503 - 1510  2005年  [査読有り]

     概要を見る

    Peer-to-peer complementary currencies can be powerful tools for promoting collaborations and building relationships on the Internet. i-WAT [1] is a proposed such currency based on WAT System [2], a polycentric complementary currency using WAT tickets as its medium of exchange. Participants spontaneously issue and circulate the tickets as needed, whose values are backed up by chains of trust. i-WAT implements the tickets electronically by exchanges of messages signed in OpenPGP [3]. This paper clarifies the trust model of i-WAT, and investigates how it is related with that of PGP [4]. To implement the model by dynamically building an appropriate web of trust (WOT), we claim that it would suffice if the behaviors of participants satisfy the following three properties: 1. mutual signing by knowing, or any two mutual acquaintances sign the public keys of each other, 2. mutual signing by participation, or the drawer and a user of an i-WAT ticket sign the public keys of each other, and 3. mutual full trust by participation, or the drawer and a user of an i-WAT ticket fully trust each other, and a recipient fully trust the corresponding user of a ticket, in the context of PGP public key signing. Likelihood of satisfaction of these properties is supported by the (dis)incentives imposed by the semantics of i-WAT. A reference implementation of i-WAT has been developed in the form of a Jabber [5] instant messaging client. We are beginning to put the currency system into practical use. Copyright © 2005 The Institute of Electronics, Information and Communication Engineers.

    DOI CiNii

  • WOT for WAT: Spinning the web of trust for peer-to-peer barter relationships

    Saito, K.

    IEICE Transactions on Communications   E88-B ( 4 ) 1503 - 1510  2005年  [査読有り]

     概要を見る

    Peer-to-peer complementary currencies can be powerful tools for promoting collaborations and building relationships on the Internet. i-WAT [1] is a proposed such currency based on WAT System [2], a polycentric complementary currency using WAT tickets as its medium of exchange. Participants spontaneously issue and circulate the tickets as needed, whose values are backed up by chains of trust. i-WAT implements the tickets electronically by exchanges of messages signed in OpenPGP [3]. This paper clarifies the trust model of i-WAT, and investigates how it is related with that of PGP [4]. To implement the model by dynamically building an appropriate web of trust (WOT), we claim that it would suffice if the behaviors of participants satisfy the following three properties:
    1. mutual signing by knowing, or any two mutual acquaintances sign the public keys of each other,
    2. mutual signing by participation, or the drawer and a user of an i-WAT ticket sign the public keys of each other, and
    3. mutual full trust by participation, or the drawer and a user of an i-WAT ticket fully trust each other, and a recipient fully trust the corresponding user of a ticket, in the context of PGP public key signing.
    Likelihood of satisfaction of these properties is supported by the (dis)incentives imposed by the semantics of i-WAT. A reference implementation of i-WAT has been developed in the form of a Jabber [5] instant messaging client. We are beginning to put the currency system into practical use.

    DOI CiNii

  • Maintaining trust in peer-to-peer barter relationships

    K Saito

    2004 INTERNATIONAL SYMPOSIUM ON APPLICATIONS AND THE INTERNET WORKSHOPS, PROCEEDINGS     582 - 588  2004年

     概要を見る

    This paper proposes a barter currency system called i-WAT[12] to promote sustainable economy in peer-to-peer internetworking. i-WAT itself is a peer-to-peer system, without necessitating a central point of authority. It uses a digitally signed, electronic form of promissory note as the medium of exchange.
    This paper illustrates how it should assist internetworking of peer-to-peer systems, and discusses, in particular how trust can be maintained in such a currency system.
    Among other means, the current design of i-WAT allows the notes to be transported over Jabber[8, 9] instant messaging protocol. A prototype of an i-WAT checkbook has been developed as a plug-in for a Jabber client. We are beginning to experiment on the actual usage of the currency system using the checkbook as well as provisional web applications.

  • Maintaining Trust in Peer-to-Peer Barter Relationships

    Proceedings of 2004 Symposium on Applications and the Internet (SAINT 2004 Workshops)     582 - 588  2004年

  • Peer-to-peer money: Free currency over the internet

    Saito, K.

    Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)   2713   404 - 414  2003年  [査読有り]

     概要を見る

    This paper proposes a resilient, alternative monetary system on the Internet called i-WAT, based on WAT System[l] which uses a form of promissory note as the medium of exchanging goods and services. i-WAT uses an electronic version of the note, ownership of which is transferred by exchanging messages signed in OpenPGP[2]. i-WAT can be used as the basis of various interpersonal/corporative transactions in the globally distributed computing environment. Specific applications being investigated include distributed consumer reports, an alternative copyright system and spam-free e-mail exchange. A prototype of an i-WAT checkbook has been developed as a plug-in for a Jabber[3] client. Experiments are ongoing.

    DOI

  • Peer-to-Peer Money: Free Currency over the Internet

    Web and Communication Technologies and Internet-Related Social Issues -- HSI 2003, LNCS 2713     404 - 414  2003年

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