Sohto Chiku

Graduate School of EIS, Yokohama National University

79-7 Tokiwadai, Hodogaya-ku, Yokohama, Kanagawa 240-8501, Japan

I am a Ph.D. course student at Graduate School of EIS, Yokohama National University (YNU), advised by Prof. Junji Shikata. I also belong to CPSEC, Advanced Cryptography Research Team, National Institute of Advanced Industrial Science and Technology (AIST) as a technical trainee. I received my Bachelor’s degree in Engineering from National Institute of Technology, Numazu College in 2022 and I received my Master’s degree in Informatics from Yokohama National University in 2024.

I am interested in the mathematical aspects of cybersecurity, particularly around cryptography. My current research focuses on cryptography with advanced functionality (e.g. functional encryption, registered encryption, privacy presearving signature, quantum cryptography).

news

Apr 17, 2025	“Hierarchical Identity-Based Matchmaking Encryption” is accepted to appear at PrivCrypt 2025!
Oct 22, 2024	I talked about “Chosen Ciphertext Secure Registration-Based Encryption” in CSS 2024 at Kobe, Japan!
Sep 27, 2024	I was selected for JSPS DC2 Research Fellowships!
Sep 24, 2024	I talked about “How to Apply Fujisaki-Okamoto Transformation to Registration-Based Encryption” in CANS 2024 at Cambridge, England!

selected publications

PC:CHS25

Hierarchical Identity-Based Matchmaking Encryption

Sohto Chiku, Keisuke Hara, and Junji Shikata

In Applied Cryptography and Network Security Workshops (PrivCrypt 2025), Nov 2025

Bib

@inproceedings{PC:CHS25,
  author = {Chiku, Sohto and Hara, Keisuke and Shikata, Junji},
  title = {Hierarchical Identity-Based Matchmaking Encryption},
  booktitle = {Applied Cryptography and Network Security Workshops (PrivCrypt 2025)},
  series = {Lecture Notes in Computer Science},
  volume = {15655},
  pages = {274-295},
  publisher = {Springer},
  year = {2025},
  month = nov
}

CANS:CHHTS24

How to Apply Fujisaki-Okamoto Transformation to Registration-Based Encryption

Sohto Chiku, Keisuke Hara, Keitaro Hashimoto, Toi Tomita, and Junji Shikata

In The 23rd International Conference on Cryptology And Network Security (CANS 2024), Sep 2024

Bib

@inproceedings{CANS:CHH+24,
  author = {Chiku, Sohto and Hara, Keisuke and Hashimoto, Keitaro and Tomita, Toi and Shikata, Junji},
  title = {How to Apply Fujisaki-Okamoto Transformation to Registration-Based Encryption},
  booktitle = {The 23rd International Conference on Cryptology And Network Security (CANS 2024)},
  series = {Lecture Notes in Computer Science},
  volume = {14906},
  pages = {145-165},
  publisher = {Springer},
  year = {2024},
  month = sep,
  url = {https://doi.org/10.1007/978-981-97-8016-7_7}
}

ProvSec:CHS23

Identity-based Matchmaking Encryption Secure against Key Generation Center

Sohto Chiku, Keisuke Hara, and Junji Shikata

In The 17th International Conference on Provable and Practical Security (ProvSec 2023), Oct 2023

Bib

@inproceedings{ProvSec:CHS23,
  author = {Chiku, Sohto and Hara, Keisuke and Shikata, Junji},
  title = {Identity-based Matchmaking Encryption Secure against Key Generation Center},
  booktitle = {The 17th International Conference on Provable and Practical Security (ProvSec 2023)},
  series = {Lecture Notes in Computer Science},
  volume = {14217},
  pages = {251–273},
  publisher = {Springer},
  year = {2023},
  month = oct
}