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. (identity-based, attribute-based, functional) encryption, matchmaking encryption, registered cryptographic primitive, proxy re-signature).

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), Jun 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 = {xxxxx},
  pages = {xx-xx},
  publisher = {Springer},
  year = {2025},
  month = jun
}

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
}