Hayato KIMURA (木村 隼人)

  • Security Researcher at Security Fundamentals Laboratory, NICT, Japan
    • mainly applied cryptography and protocol security
  • PhD Student at The University of Osaka (April 2025-Present, Supervisor: Prof. Takanori Isobe)
  • email: hytkimura[at]protonmail[dot]com
  • email(secondary): h.kimura[at]ist.osaka-u.ac.jp
  • DBLP

News

  • May 2025: Our talk will be presented at Black Hat USA 2025 Briefings (2024 acceptance rate: about 8%). URL
    • Not Sealed: Practical Attacks on Nostr, a Decentralized Censorship-Resistant Protocol
  • February 2025: Our research paper has been accepted to IEEE EuroS&P 2025. URL
    • Not in The Prophecies: Practical Attacks on Nostr

Education

  • (Apr. 2025 – Present) Ph.D. Program, Graduate School of Information Science and Technology
    The University of Osaka, Japan
    Supervisor: Prof. Takanori Isobe
  • (Apr. 2023 – Mar. 2025) Ph.D. Program, Graduate School of Information Science
    University of Hyogo, Japan
    Supervisor: Prof. Takanori Isobe
    Note: Transferred to The University of Osaka; degree not awarded.
  • (Apr. 2019 – Mar. 2021) Master's Degree in Information and Telecommunication Engineering
    Tokai University, Japan
    Supervisor: Prof. Toshihiro Ohigashi

Work History

  • (Present – Apr. 2025) NICT, Japan
    Researcher, Applied Cryptography and Application Security
  • (Mar. 2025 – Apr. 2021) LINE Corp (LY Corp), Japan
    Security Engineer, Applied Cryptography and Application Security
    Note: LINE Corp merged with Yahoo Japan Corp to form LY Corporation in October 2023

Research Interests

  • Applied Cryptography and Application Security
    • Security analysis and design of cryptographic protocols
    • Security analysis of symmetric key cryptography

Publications

Peer-reviewed Journal Papers

  1. Shogo SHIRAKI, Hayato KIMURA, Takanori ISOBE, "Looking Further into the Security of End-to-End Encryption of SFrame, " Journal of Information Processing, vol.32, pp.679-689, Sept. 2024. (paper)
  2. Hayato KIMURA, Keita EMURA, Takanori ISOBE, Ryoma ITO, Kazuto OGAWA, and Toshihiro OHIGASHI, "A Deeper Look into Deep Learning-based Output Prediction Attacks Using Weak SPN Block Ciphers, " Journal of Information Processing, vol.31, pp.550-561, Sept. 2023. (paper)
  3. Toshihiro OHIGASHI, Shuya KAWAGUCHI, Kai KOBAYASHI, Hayato KIMURA, Tatsuya SUZUKI, Daichi OKABE, Takuya ISHIBASHI, Hiroshi YAMAMOTO, Maki INUI, Ryo MIYAMOTO, Kazuyoshi FURUKAWA, Tetsuya IZU, "Detecting Fake QR codes using Information from Error-Correction, " Journal of Information Processing, vol.29, pp.548-558, Sept. 2021. (paper)
  4. Keita EMURA, Hayato KIMURA, Toshihiro OHIGASHI, and Tatsuya SUZUKI, "Privacy-Preserving Aggregation of Time-Series Data with Public Verifiability from Simple Assumptions and Its Implementations, " The Computer Journal, pp.614-630, vol.62, Issue 4, April 2019. (Impact Factor 2019 = 1.077) (paper)

Peer-reviewed International Conference Papers

  1. Hayato KIMURA, Ryoma ITO, Kazuhiko MINEMATSU, Shogo SHIRAKI and Takanori ISOBE, "Not in The Prophecies: Practical Attacks on Nostr, " 10th IEEE European Symposium on Security and Privacy (EuroS&P 2025) , June 2025. (to appear)
  2. Hayato KIMURA, Keita EMURA, Takanori ISOBE, Ryoma ITO, Kazuto OGAWA, Toshihiro OHIGASHI, "Output Prediction Attacks on Block Ciphers using Deep Learning, " Proc. 4th International Workshop on Artificial Intelligence and Industrial Internet-of-Things Security (AIoTS 2022), Rome, Italy, ACNS 2022 Workshops, LNCS 13285, , Rome, Italy, pp. 248–276, June 22-23, 2022.
  3. Hayato KIMURA, Takanori ISOBE, and Toshihiro OHIGASHI, "Neural-Network-Based Pseudo-Random Number Generator Evaluation Tool for Stream Ciphers, " Proc. CANDAR Workshops 2019, WCIS 2019 , Nagasaki, Japan, pp.333-338, Nov. 26-29, 2019.
  4. Tohru KONDO, Hidenobu WATANABE, Kai KOBAYASHI, Hayato KIMURA, and Toshihiro OHIGASHI, "Development of the Edge Computing Platform with Dynamic Modular Configuration for an IoT Platform, " Proc. PACRIM 2019 , Victoria, B.C., Canada, 6 pages, Aug. 21-23, 2019.
  5. Tatsuya SUZUKI, Keita EMURA, Hayato KIMURA, and Toshihiro OHIGASHI, "Implementation Results of Privacy-Preserving and Public Verifiable Data Aggregation Protocols, " The 12th International Workshop on Security (IWSEC 2017) , poster, Aug, 2017

ePrint

  1. Hayato Kimura, Keita Emura, Takanori Isobe, Ryoma Ito, Kazuto Ogawa, Toshihiro Ohigashi, "Output Prediction Attacks on Block Ciphers using Deep Learning, " Cryptology ePrint Archive, 2021/401, 33 pages, IACR, 2021, https://eprint.iacr.org/2021/401

Talks (non-archival)

  1. Hayato KIMURA, Ryoma ITO, Kazuhiko MINEMATSU, Shogo SHIRAKI and Takanori ISOBE, "Not Sealed: Practical Attacks on Nostr, a Decentralized Censorship-Resistant Protocol, " Black Hat USA 2025 Briefings, Aug.2025 (to appear), URL

Awards

  1. JIP Specially Selected Paper (Sept. 2023)(URL)
    • Hayato KIMURA, Keita EMURA, Takanori ISOBE, Ryoma ITO, Kazuto OGAWA, and Toshihiro OHIGASHI, "A Deeper Look into Deep Learning-based Output Prediction Attacks Using Weak SPN Block Ciphers, "
  2. IWSEC 2017 Best Poster Award (Aug. 2017)(URL)
    • Tatsuya SUZUKI, Keita EMURA, Hayato KIMURA, and Toshihiro OHIGASHI, "Implementation Results of Privacy-Preserving and Public Verifiable Data Aggregation Protocols, " The 12th International Workshop on Security (IWSEC 2017)