publications

2025

1. MobiSec:SHCS25

   Non-Recoverable Signature: Digital Signatures Torelant to Partial Disclosures

   Daiki Sasame, Keisuke Hara, Sohto Chiku, and Junji Shikata

   In The 9th International Conference on Mobile Internet Security (MobiSec 2025), Dec 2025

   Bib

   @inproceedings{MobiSec:SHCS25,
     author = {Sasame, Daiki and Hara, Keisuke and Chiku, Sohto and Shikata, Junji},
     title = {Non-Recoverable Signature: Digital Signatures Torelant to Partial Disclosures},
     booktitle = {The 9th International Conference on Mobile Internet Security (MobiSec 2025)},
     series = {XXX},
     volume = {xxxxx},
     pages = {xx-xx},
     publisher = {Springer},
     year = {2025},
     month = dec
   }

2. SecITC:MCHS25

   Adaptively Secure Matchmaking Encryption from Witness Encryption

   Taisei Matsushita, Sohto Chiku, Keisuke Hara, and Junji Shikata

   In The 18th International Conference on Security for Information Technology and Communications (SecITC 2025), Nov 2025

   Bib

   @inproceedings{SecITC:MCHS25,
     author = {Matsushita, Taisei and Chiku, Sohto and Hara, Keisuke and Shikata, Junji},
     title = {Adaptively Secure Matchmaking Encryption from Witness Encryption},
     booktitle = {The 18th International Conference on Security for Information Technology and Communications (SecITC 2025)},
     series = {Lecture Notes in Computer Science},
     volume = {xxxxx},
     pages = {xx-xx},
     publisher = {Springer},
     year = {2025},
     month = nov
   }

3. 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
   }

4. NSS:MCHS24

   How to Accomplish Key and Communication Compression Over Authentication Channels: Proxy Re-Authentication and its instantiations

   Yoshiro Matsuoka, Sohto Chiku, Keisuke Hara, and Junji Shikata

   In 18th International Conference on Network and System Security (NSS 2024), May 2025

   Bib

   @inproceedings{NSS:MCHS24,
     author = {Matsuoka, Yoshiro and Chiku, Sohto and Hara, Keisuke and Shikata, Junji},
     title = {How to Accomplish Key and Communication Compression Over Authentication Channels: Proxy Re-Authentication and its instantiations},
     booktitle = {18th International Conference on Network and System Security (NSS 2024)},
     series = {Lecture Notes in Computer Science},
     volume = {15564},
     pages = {3-20},
     publisher = {Springer},
     year = {2025},
     month = may
   }

2024

1. ePrint:CHS24

   Hierarchical Identity-Based Matchmaking Encryption

   Sohto Chiku, Keisuke Hara, and Junji Shikata

   In Cryptology ePrint Archive, Aug 2024

   Bib PDF

   @inproceedings{ePrint:CHS24,
     author = {Chiku, Sohto and Hara, Keisuke and Shikata, Junji},
     title = {Hierarchical Identity-Based Matchmaking Encryption},
     booktitle = {Cryptology ePrint Archive},
     howpublished = {Cryptology ePrint Archive, Paper 2024/1292},
     year = {2024},
     month = aug,
     note = {\url{https://eprint.iacr.org/2024/1292}},
     url = {https://eprint.iacr.org/2024/1292}
   }

2. 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}
   }

2023

1. ePrint:CHHS23

   Identity-Based Matchmaking Encryption, Revisited: Strong Security and Practical Constructions from Standard Classical and Post-Quantum Assumptions

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

   In Cryptology ePrint Archive, Sep 2023

   Bib PDF

   @inproceedings{ePrint:CHHS23,
     author = {Chiku, Sohto and Hashimoto, Keitaro and Hara, Keisuke and Shikata, Junji},
     title = {Identity-Based Matchmaking Encryption, Revisited: Strong Security and Practical Constructions from Standard Classical and Post-Quantum Assumptions},
     booktitle = {Cryptology ePrint Archive},
     howpublished = {Cryptology ePrint Archive, Paper 2023/1435},
     year = {2023},
     month = sep,
     note = {\url{https://eprint.iacr.org/2023/1435}},
     url = {https://eprint.iacr.org/2023/1435}
   }

2. ISPEC:CHS23

   Chosen Ciphertext Security for Blind Identity-based Encryption with Certified Identities

   Sohto Chiku, Keisuke Hara, and Junji Shikata

   In The 18th International Conference on Information Security Practice and Experience (ISPEC 2023), Nov 2023

   Bib

   @inproceedings{ISPEC:CHS23,
     author = {Chiku, Sohto and Hara, Keisuke and Shikata, Junji},
     title = {Chosen Ciphertext Security for Blind Identity-based Encryption with Certified Identities},
     booktitle = {The 18th International Conference on Information Security Practice and Experience (ISPEC 2023)},
     series = {Lecture Notes in Computer Science},
     volume = {14341},
     pages = {299-314},
     publisher = {Springer},
     year = {2023},
     month = nov
   }

3. 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
   }

2020