Tight reduction for generic construction of certificateless signature and its instantiation from DDH assumption. - Keitaro Hashimoto; Wakaha Ogata; Toi Tomita (IACR Cryptol. ePrint Arch., 2019)

Unrestricted and compact certificateless aggregate signature scheme. - Keitaro Hashimoto; Wakaha Ogata (Inf. Sci., 2019)

A Concrete Treatment of Efficient Continuous Group Key Agreement via Multi-Recipient PKEs. - Keitaro Hashimoto; Shuichi Katsumata; Eamonn W. Postlethwaite; Thomas Prest; Bas Westerbaan (IACR Cryptol. ePrint Arch., 2021)

How to Hide MetaData in MLS-Like Secure Group Messaging: Simple, Modular, and Post-Quantum. - Keitaro Hashimoto; Shuichi Katsumata; Thomas Prest (IACR Cryptol. ePrint Arch., 2022)

An Efficient and Generic Construction for Signal's Handshake (X3DH): Post-quantum, State Leakage Secure, and Deniable. - Keitaro Hashimoto; Shuichi Katsumata; Kris Kwiatkowski; Thomas Prest (J. Cryptol., 2022)

Identity-Based Matchmaking Encryption, Revisited: Strong Security and Practical Constructions from Standard Classical and Post-Quantum Assumptions. - Sohto Chiku; Keitaro Hashimoto; Keisuke Hara; Junji Shikata (IACR Cryptol. ePrint Arch., 2023)

How to Apply Fujisaki-Okamoto Transformation to Registration-Based Encryption. - Sohto Chiku; Keisuke Hara; Keitaro Hashimoto; Toi Tomita; Junji Shikata (CANS (2), 2024)

Security Model for Authenticated Key Exchange, Reconsidered. - Xichen Zhang; Keitaro Hashimoto; Wakaha Ogata (SCN (2), 2024)

Towards a Tightly Secure Signature in Multi-User Setting with Corruptions Based on Search Assumptions. - Hirofumi Yoshioka; Wakaha Ogata; Keitaro Hashimoto (IACR Cryptol. ePrint Arch., 2024)

Chosen-ciphertext secure code-based threshold public key encryptions with short ciphertext. - Kota Takahashi; Keitaro Hashimoto; Wakaha Ogata (Des. Codes Cryptogr., 2024)

Key Revocation in Registered Attribute-Based Encryption. - Kyoichi Asano; Nuttapong Attrapadung; Keisuke Hara; Keitaro Hashimoto; Yohei Watanabe 001 (PKC (3), 2025)

Round-Optimal Authenticated Key Exchange with Full Forward Privacy. - Koki Matsui; Shoma Kanzaki; Wakaha Ogata; Keitaro Hashimoto (IACR Commun. Cryptol., 2025)

Exploring How to Authenticate Application Messages in MLS: More Efficient, Post-Quantum, and Anonymous Blocklistable. - Keitaro Hashimoto; Shuichi Katsumata; Guillermo Pascual-Perez (IACR Cryptol. ePrint Arch., 2025)

Bundled Authenticated Key Exchange: A Concrete Treatment of (Post-Quantum) Signal's Handshake Protocol. - Keitaro Hashimoto; Shuichi Katsumata; Thom Wiggers (IACR Cryptol. ePrint Arch., 2025)

Signatures with Tight Adaptive Corruptions from Search Assumptions. - Keitaro Hashimoto; Wakaha Ogata; Yusuke Sakai 001 (IACR Cryptol. ePrint Arch., 2025)

Foundations of Multi-Designated Verifier Signature: Comprehensive Formalization and New Constructions in Subset Simulation. - Keitaro Hashimoto; Kyosuke Yamashita; Keisuke Hara (IACR Cryptol. ePrint Arch., 2025)