JO Hyungrok

Affiliation

Institute of Advanced Sciences

Job Title

Specially Appointed Assistant Professor

Research Fields, Keywords

graph theory, elliptic curve-based cryptography, post-quantum cryptography

写真a

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The Best Research Achievement in Research Career 【 display / non-display 】

  • 【Published Thesis】 Ramanujan graphs for post-quantum cryptography  2020.10

    【Published Thesis】 Full cryptanalysis of hash functions based on cubic Ramanujan graphs  2017.09

    【Published Thesis】 Cryptographic hash functions based on Triplet and Sextet graphs  2022.01

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The Best Research Achievement in the last 5 years 【 display / non-display 】

  • 【Published Thesis】 Generalized LPS Ramanujan graphs  2022.08

    【Published Thesis】 Ramanujan graphs for post-quantum cryptography  2020.10

    【Published Thesis】 Cryptographic hash functions based on Triplet and Sextet graphs  2022.01

    【Published Thesis】 Cayley hash function-map based on LPS-type Ramanujan graphs  2019.10

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Education 【 display / non-display 】

  • 2014.10
    -
    2017.3

    Kyushu University   Doctor Course   Graduated

  • 2014.3
    -
    2014.9

    釜山大学校   大学院数学科博士後期課程 数理学専攻   Doctor Course   Unfinished Course

  • 2011.3
    -
    2013.8

    釜山大学校   大学院数学科修士課程 数理学専攻   Master Course   Graduated

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Degree 【 display / non-display 】

  • Master of Mathematics - Kyushu University

  • Master of Science (Mathematics) - Pusan National University

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Campus Career 【 display / non-display 】

  • 2021.10
    　
    　

    Duty   Yokohama National UniversityInstitute of Advanced Sciences   Specially Appointed Assistant Professor  

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External Career 【 display / non-display 】

  • 2021.4
    -
    2022.3

      Lecturer  

  • 2019.5
    -
    2021.9

      Researcher  

  • 2018.4
    -
    2019.4

      Researcher  

  • 2017.4
    -
    2018.3

      Researcher  

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Academic Society Affiliations 【 display / non-display 】

  • 2024.4
    　
    　
     

    Information Processing Society of Japan (IPSJ)

  • 2024.1
    　
    　
     

    Korea Institute of Information Security & Cryptology (KIISC)

  • 2022.2
    　
    　
     

    日本応用数理学会 (JSIAM)

  • 2019.4
    　
    　
     

    電子情報通信学会 (IEICE)

  • 2017.4
    　
    　
     

    大韓数学会 (KMS)

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Research Areas 【 display / non-display 】

  • Informatics / Information security

  • Natural Science / Basic mathematics

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Thesis for a degree 【 display / non-display 】

  • Cryptanalysis on hash functions based on Ramanujan graphs

    Hyungrok JO

    2017.3

    Doctoral Thesis   Single Work    [Reviewed]

  • On p-semisimplicity of Cayley graphs

    Hyungrok JO

    2013.8

    Master Thesis   Single Work  

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Papers 【 display / non-display 】

  • Ramanujan graphs for post-quantum cryptography

    Hyungrok JO, Shingo SUGIYAMA, Yoshinori YAMASAKI

    International Symposium on Mathematics, Quantum Theory, and Cryptography, Proceedings of MQC2019, Mathematics for Industry   2020.10  [Reviewed]

    DOI

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    Language：English   Publishing type：Research paper (international conference proceedings)   Single Work  

  • Full cryptanalysis of hash functions based on cubic Ramanujan graphs

    Hyungrok JO, Christophe PETIT, Tsuyoshi TAKAGI

    IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences   2017.9  [Reviewed]

    DOI

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    Language：English   Publishing type：Research paper (scientific journal)   Single Work  

  • Hash functions based on Ramanujan graphs

    Hyungrok JO

    Special Issue on Mathematical Modelling for Next-Generation Cryptography, Mathematics for Industry   2017.7  [Reviewed]

    DOI

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    Language：English   Publishing type：Research paper (scientific journal)   Single Work  

  • Tightly Secure Identity-Based Signature from Cryptographic Group Actions

    Khuc, XT; Susilo, W; Duong, DH; Guo, FC; Jo, H; Takagi, T

    PROVABLE AND PRACTICAL SECURITY, PROVSEC 2024, PT I   14903   209 - 228   2025

    DOI Web of Science

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    Language：Japanese   Publishing type：Research paper (scientific journal)   Joint Work  

  • A Security Analysis on MQ-Sign

    Ikematsu Yasuhiko, Jo Hyungrok, Yasuda Takanori

    Information Security Applications : 24th International Conference, WISA 2023, Jeju Island, South Korea, August 23–25, 2023, Revised Selected Papers   40 - 51   2024.1

    CiNii Research

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    Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer   Joint Work  

    MQ-Sign is a variant of the UOV signature scheme proposed by Shim et al. It has been suggested as a candidate for the standardization of post-quantum cryptography in Republic of Korea (known as KpqC). Recently Aulbach et al. proposed a practical key recovery attack against MQ-Sign-RS and MQ-Sign-SS with a simple secret key S. In this paper, we propose another attack that is valid for the case of a general secret key S.

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Awards 【 display / non-display 】

  • Best Paper Award

    2023.8   KIISC (Korea Institute of Information Security and Cryptology)   A security analysis on MQ-Sign

    Individual or group name of awards：Yasuhiko Ikematsu, Hyungrok Jo, Takanori Yasuda

  • 学術優秀賞

    2021.3   在日韓国科学技術者協会  

    Individual or group name of awards：Hyungrok JO

  • Excellent Poster Award

    2015.10   九州大学IMI  

    Individual or group name of awards：Hyungrok JO

  • Excellent Presentation Award

    2013.6   大阪市立大学OCAMI  

    Individual or group name of awards：Hyungrok JO

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Other external funds procured 【 display / non-display 】

  • エクスパンダーグラフの新しい構成手法の確立とその応用

    2022.8

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    Authorship：Coinvestigator(s) 

  • ラマヌジャン・グラフの整数論による耐量子計算機暗号へのアプローチ

    2021.8 - 2021.9

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    Authorship：Principal investigator 

  • トロピカル楕円曲線論における計算困難問題の探究と暗号技術への応用

    2021.3

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    Authorship：Principal investigator 

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Presentations 【 display / non-display 】

  • On cryptographic hash functions based on cubic high-girth graph

    Hyungrok JO, Shohei SATAKE

    日本応用数理学会 第18回 研究部会連合発表会 離散システム研究部会 

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    Event date： 2022.3

    Language：Japanese   Presentation type：Oral presentation (general)  

  • Implementations on identity-based signature schemes based on variants of CSIDH

    Hyungrok JO, Junji SHIKATA

    2022年暗号と情報セキュリティシンポジウム (SCIS2022) 

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    Event date： 2022.1

    Language：Japanese   Presentation type：Oral presentation (general)  

  • ラマヌジャングラフの研究とその暗号応用

    Hyungrok JO

    CREST「現代の数理科学と連携するモデリング手法の構築」 成果報告公開シンポジウム 

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    Event date： 2021.9

    Language：Japanese   Presentation type：Poster presentation  

  • ラマヌジャングラフの研究とその暗号応用

    Hyungrok JO

    CREST「現代の数理科学と連携するモデリング手法の構築」 成果報告公開シンポジウム, 

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    Event date： 2021.9

    Language：Japanese   Presentation type：Oral presentation (general)  

  • On Ramanujan graphs in the era of Post-Quantum Cryptography

    Hyungrok JO  [Invited]

    組合せ論・モデル理論セミナー 

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    Event date： 2021.7

    Language：Japanese   Presentation type：Oral presentation (invited, special)  

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Charge of off-campus class subject 【 display / non-display 】

  • データサイエンス

    2021.9 - 2022.3 Institution：筑波大学

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    Level：Undergraduate (liberal arts) 

  • 情報リテラシー演習

    2021.4 - 2022.8 Institution：筑波大学

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    Level：Undergraduate (liberal arts) 

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Committee Memberships 【 display / non-display 】

  • Information Processing Society of Japan (IPSJ)

    2024.4  JIP (Journal of Information Processing) Editorial Committee [Network Group]

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    Committee type：Academic society 

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