KOGA Hiroki

Affiliation
Institute of Systems and Information Engineering
Official title
Professor
Sex
Male
Research fields
Theory of informatics
Research keywords
Information Theory
Information Security
Data compression
Research projects
秘密分散法の漏洩耐性に対する新しい理論の構築とその応用2026 -- 2028古賀 弘樹Japan Society for the Promotion of Science/Grant-in-Aid for Scientific Research(C)4,550,000Yen
Mathematical analyses on one-bit secret sharing schemes and their extensions2023-04 -- 2026-03KOGA HirokiJapan Society for the Promotion of Science/Grant-in-Aid for Scientific Research(C)4,030,000Yen
Construction of a Robust Algorithm for Identification of All Malicious Users of a Digital Fingerprinting Code and Characterization of the Joint Capacity2018-04 -- 2022-03KOGA HirokiJapan Society for the Promotion of Science/Grant-in-Aid for Scientific Research(C)3,900,000Yen
Developments of the Capacity Formula and Identification Algorithms for a Catch-All Digital Fingerprinting Code2014-04 -- 2017-03KOGA HirokiJapan Society for the Promotion of Science/Grant-in-Aid for Scientific Research (C)4,030,000Yen
Study on Visual Cryptology -- (current)/
Study on the Shannon Theory -- (current)/
Construction and Performance Analysis of Digital Fingerprinting Code with Identifiability of All Malicious Users2011 -- 2013KOGA HirokiJapan Society for the Promotion of Science/Grant-in-Aid for Scientific Research (C)4,030,000Yen
Coding Theorems for Information-Theoretically Secure Systems with Stochastic Encoders2008 -- 2010KOGA HirokiJapan Society for the Promotion of Science/Grant-in-Aid for Scientific Research (C)4,030,000Yen
計算量的に効率のよい秘密分散法の実現に関する研究　　　　　　　　　　　　　　　　2005 -- 2007KOGA HirokiJapan Society for the Promotion of Science/Grant-in-Aid for Young Scientists (B)3,100,000Yen
最適性をもつ視覚復号型秘密分散法の代数的な構成法に関する研究2003 -- 2004KOGA HirokiJapan Society for the Promotion of Science/Grant-in-Aid for Young Scientists (B)1,600,000Yen
more...
Academic background
1988-04 -- 1990-03The University of Tokyo Faculty of Engineering 計数工学科
1990-04 -- 1992-03The University of Tokyo Graduate School, Division of Engineering 計数工学専攻　修士課程
1992-04 -- 1995-03The University of Tokyo 大学院工学系研究科 計数工学専攻　博士課程
Degree
1995-03博士(工学)The University of Tokyo
Academic societies
-- (current)Institute of Electrical and Electronics Engineers (IEEE)
-- (current)THE INSTITUTE OF ELECTRONICS, INFORMATION AND COMMUNICATION ENGINEERS.
Honors & Awards
2013-05喜安善市賞
2013-05Paper Award
2001SITA2000奨励賞
19981998年暗号と情報セキュリティシンポジウム論文賞
Articles
  • An Explicit Construction of a Coded Caching Scheme with Heterogeneous Cache Sizes and Its Extension via Optimization
    KOGA Hiroki
    IEICE Trans. on Fundamentals/E109-A(3)/pp.463-472, 2026-03
  • An Explicit Construction of a Coded Caching Scheme with Heterogeneous Cache Sizes and Its Extension via Optimization
    Nagaya Akihito; Yoneyama Tomoki; Koga Hiroki
    IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES/E109A(3)/pp.463-472, 2026-03
  • An Explicit Construction of a Coded Caching Scheme with Heterogeneous Cache Sizes
    KOGA Hiroki
    Proceedings of 2024 International Symposium on Information Theory and Its Applications/pp.340-345, 2024-11
  • Constructions of a Visual Cryptography Scheme Using an Affine Resolvable BIBD
    KOGA Hiroki
    Proceedings of 2024 International Symposium on Information Theory and Its Applications/pp.188-193, 2024-11
  • Recent Progress in Visual Cryptography
    古賀 弘樹
    J. IEICE/106(1)/pp.39-46, 2023-01
  • Evaluation of the Optimal Relative Difference of Superimposed All the Shares for a (t,n-Threshold Visual Cryptography Scheme
    Koga Hiroki
    IEICE Technical Report/pp.439-444, 2023-03
  • 一般のアクセス構造に対するランプ型秘密分散法の最適な構成について
    古賀 弘樹
    IEICE Technical Report/pp.433-438, 2023-03
  • On the Optimal Construction of a Visual Cryptography Scheme for Multiple Secret Images
    Koga Hiroki
    Proceedings of 2022 International Symposium on Information Theory and its Applications/pp.168-172, 2022-10
  • On the Optimum Achievable Rates of a Coded Caching Scheme with Small Cache Memory
    Koga Hiroki
    Proceedings of 2022 International Symposium on Information Theory and its Applications/p.44, 2022-10
  • Construction of the Visual Cryptography Scheme With the Maximum Relative Difference Under a Strong General Access Structure
    Koga Hiroki
    Proceedings of 2022 IEEE International Symposium on Informaiton Theory/pp.696-701, 2022-06
  • Coding Theorems on Digital Fingerprinting Coding under Informed and Uninformed Setups
    Koga Hiroki
    2021 IEEE Information Theory Workshop, 2021-10
  • Optimal Basis Matrices of a Visual Cryptography Scheme with Meaningful Shares and Analysis of Its Security
    Sekine Kyohei; 古賀 弘樹
    IEICE Trans. on Fundamentals/E104-A (9)/pp.1235-1244, 2021-09
  • シェアの回転により複数の秘密画像を復元できる視覚暗号の最適な構成法
    古賀 弘樹; 関根 恭平
    信学技報 IT2020-131, 2021-03
  • 視覚暗号の最近の進歩
    古賀 弘樹
    信学技報 IT2020-25, 2020-12
  • An Ideal Secret Sharing Scheme Realizing an Access Structure Based on a Finite Projective Plane of Order 3
    Koga Hiroki; Okawa Yohei
    Proceedings of 2020 IEEE ISIT/pp.852-855, 2020-10
  • New Constructions of an Evolving 2-Threshold Scheme Based on Binary or D-ary Prefix Codes
    Koga Hiroki; Okamura Ryo
    Proceedings of ISITA 2020/pp.432-436, 2020-10
  • Optimal Basis Matrices of a Visual Cryptography Scheme with Meaningful Shares and Analysis of Its Security
    Koga Hiroki
    Proceedings of 2020 ISITA 2020/pp.422-426, 2020-10
  • Coding Theorems on the Simple Capacity for Digital Fingerprinting Codes
    Koga Hiroki
    Proceedings of 2020 ISITA 2020/pp.61-65, 2020-10
  • A Construction of the (4; n)-Threshold Visual Cryptography Scheme Using a 3-Design
    Koutaro Okada; Hiroki Koga
    IEICE Proceeding Series/(55)/pp.223-227, 2018
    CiNii
  • A Construction of Secret Sharing Schemes with Threshold 3 for Countably Infinite Participants
    Taksahi Hisatome; Hiroki Koga
    IEICE Proceeding Series/(55)/pp.513-513, 2018
    CiNii
  • A Higher Order Analysis of the Joint Capacity of Digital Fingerprinting Codes against the Interleaving Attack
    Koga Hiroki
    Proceedings of 2016 ACM Workshop on Information Hiding and Multimedia Security/pp.23-28, 2016-06
  • New Coding Theorems for Fixed-Length Source Coding and Shannon's Cipher System with a General Source
    Koga Hiroki
    Proceedings of 2008 International Symposium on Information Theory, 2008-12
  • New Fundamental Properties on a Secret-key Cryptosystem under Guessing Secrecy Criteria
    Kamiya Shota; Koga Hiroki
    PROCEEDINGS OF 2016 INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY AND ITS APPLICATIONS (ISITA 2016)/pp.345-349, 2016
  • On a partition of a finite set and its relationships to encoding tasks and the Rényi entropy
    Koga Hiroki
    Proceedings of 2015 IEEE International Symposium on Information Theory/pp.1452-1455, 2015-06
  • A (K, n)-Threshold Scheme with Detectability of All the Cheaters Based on a Certain Majority Rule
    島崎 憲明; 古賀 弘樹
    IEICE technical report. Information theory/114(224)/pp.19-24, 2014-09
    CiNii
  • more...
Books
  • Digital transmission of Information
    古賀 弘樹;
    1997-01
  • Information-Spectrum Methods in Information Thoery
    古賀 弘樹
    2003-10
  • 現代数理科学事典
    古賀 弘樹
    岩波書店, 2009-12
  • Elements of Information Theory
    Thomas M. Cover; Joy A. Thomas (山本; 古賀 ; 有村 ; 岩本訳) ; + 古賀...
    共立出版社, 2012-07
  • Coding Theorems on the Worst-Case Redundancy of Fixed-Length Coding for a General Source
    Koga Hiroki; Arimura Mitsuharu; Iwata Ken-ichi
    2011 IEEE INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY PROCEEDINGS (ISIT)/IEEE/pp.1327-1331, 2011-01
  • A Simple Secret Sharing Scheme Using a Key and its Security against Substitution of Shares
    Koga Hiroki
    2010 IEEE INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY/IEEE/pp.2483-2487, 2010-01
  • Proposal of an asymptotically contrast-ideal (t, n)-threshold visual secret sharing scheme
    Koga Hiroki; Ueda Etsuyo
    2006 IEEE International Symposium on Information Theory, Vols 1-6, Proceedings/IEEE/pp.912-916, 2006-01
  • New Coding Theorems for Fixed-Length Source Coding and Shannon's Cipher System with a General Source
    Koga Hiroki
    2008 INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY AND ITS APPLICATIONS, VOLS 1-3/IEEE/pp.250-255, 2008-01
  • A Construction of a Visual Secret Sharing Scheme for Plural Secret Images and its Basic Properties
    Koga Hiroki; Miyata Masayuki
    2008 INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY AND ITS APPLICATIONS, VOLS 1-3/IEEE/pp.24-29, 2008-01
Conference, etc.
  • (3,n)しきい値型視覚暗号におけるすべてのシェアを重ねたときの相対差の上界と最適性について
    古賀 弘樹; 御手洗 尚輝
    電子情報通信学会　情報理論研究会/2026-03-16--2026-03-17
  • 加法型(n,n)しきい値法における1ビットLeakage間の最悪の統計的距離の一般公式
    古賀 弘樹; 阿部 浩人
    第48回情報理論とその応用シンポジウム/2025-11-25--2025-11-28
  • 拡大体上の関数による強いしきい値ランプ型秘密分散法の構成とその安全性について
    古賀 弘樹; 帶施 侑介
    第48回情報理論とその応用シンポジウム/2025-11-25--2025-11-28
  • 不均一なキャッシュメモリに対する最適化された符号化キャッシュ方式とその性能評価
    古賀 弘樹; 米山 友貴
    第48回情報理論とその応用シンポジウム/2025-11-25--2025-11-28
  • 加法型(n,n)しきい値法における1ビットLeakageの変動距離の評価
    古賀 弘樹
    第47回情報理論とその応用シンポジウム/2024-12-10--2024-12-13
  • 加法型(n, n) しきい値法におけるLeakage分布間の変動距離の最悪指数部について
    古賀 弘樹
    電子情報通信学会　情報理論研究会/2025-03-05--2025-03-06
  • Theory and Examples of One-Bit Secret Sharing
    KOGA Hiroki
    2024 International Symposium on Information Theory and Its Applications/2024-11-10--2024-11-13
  • 異なるサイズのキャッシュメモリをもつ符号化キャッシュ方式の達成可能レートについて
    古賀 弘樹
    電子情報通信学会　情報理論研究会/2024/03/13--2024/03/14
  • 1ビットの秘密情報に対するしきい値型秘密分散法の構成とその離散フーリエ変換を用いた安全性解析
    古賀 弘樹
    電子情報通信学会　情報理論研究会/2024/03/13--2024/03/14
  • Coding Theorems on the Simple Capacity for Digital Fingerprinting Codes
    古賀 弘樹
    Technical Committee on Information Theory/2020-03-10--2020-03-11
  • An Ideal Secret Sharing Scheme Realizing an Access Structure Based on a Projective Plane of Order 3
    古賀 弘樹
    The 42nd Symposium on Information Theory and Its Applications/2019-11-26--2019-11-29
  • Optimal Construction of the Basis Matrices of an Extended Visual Cryptography Scheme Using Integer Programming
    古賀 弘樹
    The 42nd Symposium on Information Theory and Its Applications/2019-11-26--2019-11-29
  • A Construction of the (4; n)-Threshold Visual Cryptography Scheme Using a 3-Design
    Okada Koutaro; Koga Hiroki
    15th International Symposium on Information Theory and its Applications (ISITA)/2018-10-28--2018-10-31
  • A Lower Bound on the Joint Capacity of Digital Fingerprinting Codes Using Score Functions Based on Log-Likelihood Ratio
    Koga Hiroki
    IEEE International Symposium on Information Theory (ISIT)/2018-06-17--2018-06-22
  • 数理計画法を用いた視覚暗号の基本行列の2種類の最適化について
    Koga Hiroki
    第39回情報理論とその応用シンポジウム/2016-12-13--2016-12-16
  • BIBDを用いたプログレッシブ型(3,n)-視覚暗号の構成とその最適性
    Koga Hiroki
    電子情報通信学会情報理論研究会/2017-05-22--2017-05-23
  • 平文と鍵の推測確率を考慮した共通鍵暗号システムの基本的性質
    Koga Hiroki
    電子情報通信学会情報理論研究会/2016-03-10--2016-03-11
  • 一般のアクセス構造に対する整数計画法を用いた最適な視覚復号型秘密分散法の構成とその応用
    Koga Hiroki
    電子情報通信学会情報理論研究会/2016-05-19--2016-05-20
  • 意図されないメッセージに対する秘匿性を考慮したインデックス符号
    Koga Hiroki
    電子情報通信学会情報理論研究会/2017-03-09--2017-03-10
  • JPEG画像の消失部分を復元できる電子透かしの提案と性能評価
    古賀 弘樹
    電子情報通信学会情報理論研究会/2015-09-04--2015-09-04
  • 複数のしきい値型アクセス構造に基づく視覚復号型秘密分散法の提案とその拡張
    西住空也; 古賀 弘樹
    電子情報通信学会情報理論研究会/2015-07-13--2015-07-14
  • 連続分布に基づき符号語が生成される電子指紋符号の容量の下界について
    古賀 弘樹
    電子情報通信学会情報理論研究会/2015-05-21--2015-05-22
  • Evaluation of the Joint Capacity of Digital Fingerprinting Codes against the Interleaving Attack
    古賀 弘樹; 板橋薫
    電子情報通信学会情報理論研究会/2016-03-10--2016-03-11
  • On the Achievable Rate Region in the Optimistic Sense for Independent Coding of Two Correlated General Sources
    古賀 弘樹
    電子情報通信学会情報理論研究会/2011-09-29--2011-09-30
  • Coding Theorems on the Worst-Case Redundancy of Fixed-Length Coding for a General Source
    Koga Hiroki; Arimura Mitsuharu; Iwata Ken-ichi
    IEEE International Symposium on Information Theory (ISIT)/2011-07-31--2011-08-05
  • more...
Teaching
2026-04 -- 2026-08Seminar in Empowerment Informatics IUniversity of Tsukuba.
2026-04 -- 2026-08Seminar in Intelligent Interaction Technologies XIII (Activity Participation in Academic Social Action Program)University of Tsukuba.
2026-10 -- 2026-12Information and Coding TheoryUniversity of Tsukuba.
2026-07 -- 2026-08Laboratory Work in Intelligent Interaction Systems AUniversity of Tsukuba.
2026-04 -- 2026-08Research in Empowerment Informatics IUniversity of Tsukuba.
2026-04 -- 2026-08Collaboratory Research Workshop in Intelligent and Mechanical Interaction Systems IIaUniversity of Tsukuba.
2026-04 -- 2026-06Tools and Practices for Intelligent Interaction Systems BUniversity of Tsukuba.
2026-10 -- 2027-02Conference Paper and Journal Paper Writing Exercise in Empowerment InformaticsUniversity of Tsukuba.
2026-04 -- 2026-08Seminar in Intelligent Interaction Technologies VII (English Presentation Practice)University of Tsukuba.
2026-04 -- 2026-08Research in Intelligent Interaction Technologies VUniversity of Tsukuba.
more...
Talks
  • AND攻撃に耐性をもつ結託耐性符号の容量について
    古賀弘樹
    電子情報通信学会　情報理論研究会/2010-03-05
  • 情報スペクトル的手法の発展とその秘密分散法への応用
    古賀弘樹
    電子情報通信学会　情報理論研究会/2009-12-01
Professional activities
2019-06 -- 2021-05IEICE情報理論とその応用サブソサイエティ サブソサイエティ長
2017-05 -- 2019-05IEICE情報理論とその応用サブソサイエティ 副サブソサイエティ長
University Management
2018-04 -- 2020-03専攻学務・カリキュラム副委員長

(Last updated: 2026-05-04)