publications | Sohto Chiku

2026

Domestic Conferences

ISEC:ICS26

標準モデルで適応的安全な格子に基づくフォワード安全署名方式

石橋錬，知久奏斗，四方順司

In 信学技報, May 2026

@inproceedings{ISEC:ICS26,
  author = {石橋錬，知久奏斗，四方順司},
  title = {標準モデルで適応的安全な格子に基づくフォワード安全署名方式},
  booktitle = {信学技報},
  year = {2026},
  volume = {vol. 126, no. 40, ISEC2026-7},
  pages = {14-21},
  month = may
}

SCIS:MHTCS26

公開鍵検索可能暗号から認証付き公開鍵検索可能暗号の一般的構成法

牧野雄太，原啓祐，冨田斗威，知久奏斗，四方順司

In 2026年暗号と情報セキュリティシンポジウム（SCIS2026）, Jan 2026

Bib

@inproceedings{SCIS:MHTCS26,
  author = {牧野雄太，原啓祐，冨田斗威，知久奏斗，四方順司},
  title = {公開鍵検索可能暗号から認証付き公開鍵検索可能暗号の一般的構成法},
  booktitle = {2026年暗号と情報セキュリティシンポジウム（SCIS2026）},
  year = {2026},
  month = jan,
  pages = {4C4-3}
}

SCIS:MHCS26

Bi-Selective Opening安全なIDベース暗号

水谷雄亮，原啓祐，知久奏斗，四方順司

In 2026年暗号と情報セキュリティシンポジウム（SCIS2026）, Jan 2026

Bib

@inproceedings{SCIS:MHCS26,
  author = {水谷雄亮，原啓祐，知久奏斗，四方順司},
  title = {Bi-Selective Opening安全なIDベース暗号},
  booktitle = {2026年暗号と情報セキュリティシンポジウム（SCIS2026）},
  year = {2026},
  month = jan,
  pages = {1C1-3}
}

2025

International Conferences

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
}

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
}

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
}

Domestic Conferences

ISEC:ICS25

格子に基づく効率的なフォワード安全署名方式

石橋錬，知久奏斗，四方順司

In 信学技報, Nov 2025

Bib

@inproceedings{ISEC:ICS25,
  author = {石橋錬，知久奏斗，四方順司},
  title = {格子に基づく効率的なフォワード安全署名方式},
  booktitle = {信学技報},
  year = {2025},
  volume = {vol. 125, no. 238, ISEC2025-77},
  pages = {27-34},
  month = nov
}

CSS:SHCS25

不完全な署名情報からの偽造耐性を持つ電子署名方式の提案

笹目大輝，原啓祐，知久奏斗，四方順司

In コンピュータセキュリティシンポジウム2025（CSS2025）, Oct 2025

Bib

@inproceedings{CSS:SHCS25,
  author = {笹目大輝，原啓祐，知久奏斗，四方順司},
  title = {不完全な署名情報からの偽造耐性を持つ電子署名方式の提案},
  booktitle = {コンピュータセキュリティシンポジウム2025（CSS2025）},
  year = {2025},
  month = oct,
  pages = {4G4-3}
}

CSS:MCHS25

Witness Encryptionによる適応的安全なMatchmaking Encryptionの構成

松下大晟，知久奏斗，原啓祐，四方順司

In コンピュータセキュリティシンポジウム2025（CSS2025）, Oct 2025

Bib

@inproceedings{CSS:MCHS25,
  author = {松下大晟，知久奏斗，原啓祐，四方順司},
  title = {Witness Encryptionによる適応的安全なMatchmaking Encryptionの構成},
  booktitle = {コンピュータセキュリティシンポジウム2025（CSS2025）},
  year = {2025},
  month = oct,
  pages = {4G4-4}
}

2024

International Conferences

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}
}

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
}

Preprints

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}
}

Domestic Conferences

CSS:CHHTS24

CCA安全な登録ベース暗号

知久奏斗，原啓祐，橋本啓太郎，冨田斗威，四方順司

In コンピュータセキュリティシンポジウム2024（CSS2024）, Oct 2024

Bib

@inproceedings{CSS:CHHTS24,
  author = {知久奏斗，原啓祐，橋本啓太郎，冨田斗威，四方順司},
  title = {CCA安全な登録ベース暗号},
  booktitle = {コンピュータセキュリティシンポジウム2024（CSS2024）},
  year = {2024},
  month = oct,
  pages = {1H4-2}
}

ISEC:MCHS24

鍵圧縮及びデータ圧縮を可能にするプロキシ再認証方式

松岡耀志朗，知久奏斗，橋本啓太郎，原啓祐，四方順司

In 信学技報, Mar 2024

Bib

@inproceedings{ISEC:MCHS24,
  author = {松岡耀志朗，知久奏斗，橋本啓太郎，原啓祐，四方順司},
  title = {鍵圧縮及びデータ圧縮を可能にするプロキシ再認証方式},
  booktitle = {信学技報},
  year = {2024},
  volume = {vol. 123, no. 424, ISEC2023-825},
  pages = {52-59},
  month = mar
}

SCIS:CHHS24

BDH仮定に基づく高効率かつ強安全なIDベースマッチメイキング暗号

知久奏斗，橋本啓太郎，原啓祐，四方順司

In 2024年暗号と情報セキュリティシンポジウム（SCIS2024）, Jan 2024

Bib

@inproceedings{SCIS:CHHS24,
  author = {知久奏斗，橋本啓太郎，原啓祐，四方順司},
  title = {BDH仮定に基づく高効率かつ強安全なIDベースマッチメイキング暗号},
  booktitle = {2024年暗号と情報セキュリティシンポジウム（SCIS2024）},
  year = {2024},
  month = jan,
  pages = {3C1-3}
}

2023

International Conferences

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
}

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
}

Preprints

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}
}

Domestic Conferences

ISEC:CHS23b

階層型IDベースマッチメイキング暗号

知久奏斗，原啓祐，四方順司

In 信学技報, Jul 2023

Bib

@inproceedings{ISEC:CHS23b,
  author = {知久奏斗，原啓祐，四方順司},
  title = {階層型IDベースマッチメイキング暗号},
  booktitle = {信学技報},
  year = {2023},
  volume = {vol. 122，no. 428，ISEC2022-75},
  pages = {60-67},
  month = jul
}

ISEC:CHS23a

鍵生成センターに対して安全なIDベースマッチメイキング暗号

知久奏斗，原啓祐，四方順司

In 信学技報, Mar 2023

Bib

@inproceedings{ISEC:CHS23a,
  author = {知久奏斗，原啓祐，四方順司},
  title = {鍵生成センターに対して安全なIDベースマッチメイキング暗号},
  booktitle = {信学技報},
  year = {2023},
  volume = {vol. 123, no. 129, ISEC2023-23},
  pages = {179-186},
  month = mar
}