勝又 秀一
自己紹介.
現在，主任研究員としてPQShield Ltd, U.K.に所属しています．勤務地は国内です．また、協力研究員として産業技術総合研究所 (AIST)にも所属しています。その前は，主任研究員としてAIST，および，リサーチコンサルタントとしてPQShield Ltd, U.K.に所属していました．
主な専門は，量子計算機に対しても安全性が保証される道具に基づく．暗号方式や暗号プロトコルの設計や，安全性解析です（通称，Post-Quantum Cryptography: PQC）．例えば，リング/ブラインド署名やID/属性ベース暗号などの様々な署名・暗号化方式，ゼロ知識証明，セキュアメッセージングプロトコルなどの構成や安全性解析を今まで扱ってきました．
もし私の研究に興味をもっていただけたら，ぜひ気軽に声をかけてください．また，PQShieldは現在求人していますので，正社員研究員・ポスドク・インターンとして興味があれば，PQShieldのキャリアページを見るか，私に直接連絡してください．
連絡先: shuichi.katsumata [at] pqshield.com OR shuichi.katsumata000 [at] gmail.com
研究成果
未刊行論文
Collisions in Supersingular Isogeny Graphs and the SIDH-based Identification Protocol. Wissam Ghantous, Shuichi Katsumata, Federico Pintore, Mattia Veroni.
査読付き国際会議/論文
2024
Two-Round Threshold Signature from Algebraic One-More Learning with Errors. Thomas Espitau, Shuichi Katsumata, Kaoru Takemure.
CRYPTO 2024. ePrint.
Adaptively Secure 5 Round Threshold Signatures from MLWE/MSIS and DL with Rewinding. Shuichi Katsumata, Kaoru Takemure, Michael Reichle.
CRYPTO 2024. To Appear.
Raccoon: A Masking-Friendly Signature Proven in the Probing Model. Rafael del Pino, Shuichi Katsumata, Thomas Prest, Mélissa Rossi.
CRYPTO 2024. To Appear.
Threshold Raccoon: Practical Threshold Signatures from Standard Lattice Assumptions. Rafael del Pino, Shuichi Katsumata, Mary Maller, Fabrice Mouhartem, Thomas Prest, Markku-Juhani O. Saarinen.
EUROCRYPT 2024. ePrint.
More Efficient Protocols for Post-Quantum Secure Messaging. Keitaro Hashimoto, Shuichi Katsumata, Eamonn W. Postlethwaite, Thomas Prest, Bas Westerbaan.
Real World Crypto 2024. (Contents from [KKPP20@ASIACRYPT] ePrint. + [HKKPW21@CCS] ePrint.)
Breaking Parallel ROS: Implication for Isogeny and Lattice-based Blind Signatures. Shuichi Katsumata, Yi-Fu Lai, Michael Reichle.
PKC 2024. ePrint.
Anonymous Reputation Systems with Revocation, Revisited. Ryuya Hayashi, Shuichi Katsumata, Yusuke Sakai.
FC 2024. Preproceeding.
2023
Practical Round-Optimal Blind Signatures in the ROM from Standard Assumptions. Shuichi Katsumata, Michael Reichle, Yusuke Sakai.
ASIACRYPT 2023. ePrint.
CSI-Otter: Isogeny-based (Partially) Blind Signatures from the Class Group Action with a Twist. Shuichi Katsumata, Yi-Fu Lai, Jason T. LeGrow, Ling Qin.
Signature for Objects: Formalizing How to Authenticate Physical Data and More. Ryuya Hayashi, Taiki Asano, Junichiro Hayata, Takahiro Matsuda, Shota Yamada, Shuichi Katsumata, Yusuke Sakai, Tadanori Teruya, Jacob Schuldt, Nuttapong Attrapadung, Goichiro Hanaoka, Kanta Matsuura, Tsutomu Matsumoto.
FC 2023. Proceeding.
Metadata Protection for MLS and Its Variants. Keitaro Hashimoto, Shuichi Katsumata, Thomas Prest.
Real World Crypto 2023. video. (A version of [HKP22@CCS]. ePrint.)
2022
How to Hide MetaData in MLS-Like Secure Group Messaging: Simple, Modular, and Post-Quantum. Keitaro Hashimoto, Shuichi Katsumata, Thomas Prest,
ACM CCS 2022. ePrint.
A New Framework For More Efficient Round-Optimal Lattice-Based (Partially) Blind Signature via Trapdoor Sampling. Rafael del Pino, Shuichi Katsumata.
CRYPTO 2022. ePrint.
Group Signatures and More from Isogenies and Lattices: Generic, Simple, and Efficient. Ward Beullens, Samuel Dobson, Shuichi Katsumata, Yi-Fu Lai, Federico Pintore.
EUROCRYPT 2022. ePrint.
2021
Statistical ZAPs from Group-Based Assumptions. Geoffroy Couteau, Shuichi Katsumata, Elahe Sadeghi, Bogdan Ursu.
TCC 2021. ePrint. video (by Elahe Sadeghi)A New Simple Technique to Bootstrap Various Lattice Zero-Knowledge Proofs to QROM Secure NIZKs. Shuichi Katsumata.
CRYPTO 2021. ePrint. video. (Longer 50mins version is available below.)A Concrete Treatment of Efficient Continuous Group Key Agreement via Multi-Recipient PKEs. Keitaro Hashimoto, Shuichi Katsumata, Eamonn W. Postlethwaite, Thomas Prest, Bas Westerbaan.
ACM CCS 2021. ePrint. video (by Keitaro Hashimoto).Revisiting Fuzzy Signatures: Towards a More Risk-Free Cryptographic Authentication System based on Biometrics. Shuichi Katsumata, Takahiro Matsuda, Wataru Nakamura, Kazuma Ohara, Kenta Takahashi.
Round-Optimal Blind Signatures in the Plain Model from Classical and Quantum Standard Assumptions. Shuichi Katsumata, Ryo Nishimaki, Shota Yamada, Takashi Yamakawa.
EUROCRYPT 2021. ePrint. video (by Ryo Nishimaki).
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.
PKC 2021. ePrint. video (by Keitaro Hashimoto).
2020
Adaptively Secure Inner Product Encryption from LWE. Shuichi Katsumata, Ryo Nishimaki, Shota Yamada, Takashi Yamakawa.
ASIACRYPT 2020. ePrint. video (by Shota Yamada).
Scalable Ciphertext Compression Techniques for Post-Quantum KEMs and their Applications. Shuichi Katsumata, Kris Kwiatkowski, Federico Pintore, Thomas Prest.
ASIACRYPT 2020. ePrint. video (by Thomas Prest).
Calamari and Falafl: Logarithmic (Linkable) Ring Signatures from Isogenies and Lattices. Ward Beullens, Shuichi Katsumata, Federico Pintore.
ASIACRYPT 2020. ePrint. video (by Federico Pintore).
Adaptively Secure Constrained Pseudorandom Functions in the Standard Model. Alex Davidson, Shuichi Katsumata, Ryo Nishimaki, Shota Yamada, Takashi Yamakawa.
CRYPTO 2020. ePrint. video (by Takashi Yamakawa).
*(Historical Note: This is a major updated version of eprint:DKNYY18 with many new results, which itself is a merged version of eprint:DavNis18 and eprint:KatYam18.)
Exposing Private User Behaviors of Collaborative Filtering via Model Inversion Techniques. Seira Hidano, Takao Murakami, Shuichi Katsumata, Shinsaku Kiyomoto, Goichiro Hanaoka.
PETS/PoPETS 2020. Proceedings.
Non-Interactive Zero-Knowledge in Pairing-Free Groups from Weaker Assumptions. Geoffroy Couteau, Shuichi Katsumata, Bogdan Ursu.
EUROCRYPT 2020. ePrint. video (by Bogdan Ursu).
Compact NIZKs from Standard Assumptions on Bilinear Maps. Shuichi Katsumata, Ryo Nishimaki, Shota Yamada, Takashi Yamakawa.
EUROCRYPT 2020. ePrint. video.
Lossy CSI-FiSh: Efficient Signature Scheme with Tight Reduction to Decisional CSIDH-512. Ali El Kaafarani, Shuichi Katsumata, Federico Pintore
PKC 2020. ePrint. video (by Federico Pintore).
2019
Exploring Constructions of Compact NIZKs from Various Assumptions. Shuichi Katsumata, Ryo Nishimaki, Shota Yamada, Takashi Yamakawa.
Identity-Based Encryption with Security against the KGC: A Formal Model and Its Instantiation from Lattices. Keita Emura, Shuichi Katsumata, Yohei Watanabe.
ESORICS 2019. ePrint.
Group Signatures without NIZK: From Lattices in the Standard Model. Shuichi Katsumata, Shota Yamada.
EUROCRYPT 2019. ePrint.
Designated Verifier/Prover and Preprocessing NIZKs from Diffie-Hellman Assumptions. Shuichi Katsumata, Ryo Nishimaki, Shota Yamada, Takashi Yamakawa.
EUROCRYPT 2019. ePrint. video.
Non-Zero Inner Product Encryption Schemes from Various Assumptions: LWE, DDH and DCR. Shuichi Katsumata, Shota Yamada.
PKC 2019. ePrint.
Lattice-Based Revocable (Hierarchical) IBE with Decryption Key Exposure Resistance. Shuichi Katsumata, Takahiro Matsuda, Atsushi Takayasu.
PKC 2019. ePrint.
2018
Tighter Security Proofs for GPV-IBE in the Quantum Random Oracle Model. Shuichi Katsumata, Shota Yamada, Takashi Yamakawa.
ASIACRYPT 2018. (Invited to Journal of Cryptography.) ePrint.
Attribute-Based Signatures for Unbounded Languages from Standard Assumptions. Yusuke Sakai, Shuichi Katsumata, Nuttapong Attrapadung, Goichiro Hanaoka.
ASIACRYPT 2018. ePrint.
Attribute-Based Signatures for Unbounded Circuits in the ROM and Efficient Instantiations from Lattices. Ali El Kaafarani, Shuichi Katsumata.
PKC 2018. ePrint.
Anonymous Reputation Systems Achieving Full Dynamicity from Lattices. Ali El Kaafarani, Shuichi Katsumata, Ravital Solomon.
FC 2018. Proceeding.
2017
On the Untapped Potential of Encoding Predicates by Arithmetic Circuits and Their Applications. Shuichi Katsumata.
ASIACRYPT 2017. ePrint. video.
Model Inversion Attacks for Prediction Systems: Without Knowledge of Non-Sensitive Attributes. Seira Hidano, Takao Murakami, Shuichi Katsumata, Shinsaku Kiyomoto, Goichiro Hanaoka.
PST 2017. Proceedings.
2016
Partitioning via Non-linear Polynomial Functions: More Compact IBEs from Ideal Lattices and Bilinear Maps. Shuichi Katsumata, Shota Yamada.
ASIACRYPT 2016. ePrint. video.
2015
Robust Cost Sensitive Support Vector Machine. Shuichi Katsumata, Akiko Takeda.
AISTATS 2015. Proceedings.
2014
Constructing Subspace Membership Encryption through Inner Product Encryption. Shuichi Katsumata, Noboru Kunihiro.
ProvSec 2014. Proceedings.
査読付き論文誌論文
2024
Compact NIZKs from Standard Assumptions on Bilinear Maps. Shuichi Katsumata, Ryo Nishimaki, Shota Yamada, Takashi Yamakawa.
Journal of Cryptology, Volume 37, 2024. Springer. (Full version of [KNYY20@EC]).
2023
Group Signatures and More from Isogenies and Lattices: Generic, Simple, and Efficient. Ward Beullens, Samuel Dobson, Shuichi Katsumata, Yi-Fu Lai, Federico Pintore.
Designs, Codes and Cryptography, 2023. Springer. To appear. (Full version of [BDKLP22@EC]
Direct Computation of Branching Programs and its Applications to More Efficient Lattice-based Cryptography. Shuichi Katsumata, Toi Tomita, Shota Yamada.
Designs, Codes and Cryptography, 2023. Springer.
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.
Journal of Cryptology, Volume 35, 2022. Springer. (Full version of [HKKP22@PKC]).
Identity-Based Encryption with Security against the KGC: A Formal Model and Its Instantiation from Lattices. Keita Emura, Shuichi Katsumata, Yohei Watanabe.
Theoretical Computer Science, Volume 900, 2022. Elsevier. (Full version of [EKW19@ESORICS]).
2021
Identity-Based Encryption with Security against the KGC: A Formal Model and Its Instantiation from Lattices. Keita Emura, Shuichi Katsumata, Yohei Watanabe.
Theoretical Computer Science, Volume 900, 2021. Elsevier. (Full version of [EKW19@ESORICS]).
Compact Designated Verifier NIZKs from the CDH Assumption Without Pairings. Shuichi Katsumata, Ryo Nishimaki, Shota Yamada, Takashi Yamakawa.
Journal of Cryptology, Volume 34, 2021. Springer. (Merged and revised version of [KNYY19@EC] and [KNYY19@C]).Tighter Security Proofs for GPV-IBE in the Quantum Random Oracle Model. Shuichi Katsumata, Shota Yamada, Takashi Yamakawa.
Journal of Cryptology, Volume 34, 2021. Springer. (Full version of [KYY18@AC]).
2020
Lattice-Based Revocable (Hierarchical) IBE with Decryption Key Exposure Resistance. Shuichi Katsumata, Takahiro Matsuda, Atsushi Takayasu.
Theoretical Computer Science, Volume 809, 2020. Elsevier. (Full version of [KMT19@PKC]).
2018
Model Inversion Attacks for Prediction Systems: Without Knowledge of Non-Sensitive Attributes. Seira Hidano, Takao Murakami, Shuichi Katsumata, Shinsaku Kiyomoto, Goichiro Hanaoka.
IEICE Transactions E101-D(11), 2018. (Full version of [HMKKH18@PST]).
2017
Constructing Subspace Membership Encryption through Inner Product Encryption. Shuichi Katsumata, Noboru Kunihiro.
IEICE Transactions E100-A(9), 2017. (Full version of [KK14@ProvSec]).
講演
Challenges of Schnorr-like Post-Quantum Blind Signatures.
AB+ Attributes and Blindness, May, 2024.CSI-Otter: Isogeny-based (Partially) Blind Signatures from the Class Group Action with a Twist.
22th Forum on Information Technology, September, 2023. (slides)Challenges and Solutions to Post-Quantum Secure Messaging.
ACNS 2023, Keynote Speaker, June, 2023. (slides).
The 3rd Yanqi Lake International PQC Standardization and Application Workshop, July, 2023.Metadata Protection for MLS and Its Variants.
Real World Crypto, March, 2023. (slides, video).耐量子計算暗号とセキュア・メッセージング.
MIT Technology Review: Innovators Under 35 Japan Summit 2022 in Nihonbashi, December, 2022.耐量子計算暗号の標準化動向.
Hardware Security Forum, December, 2022.Secure Messaging in a Post-Quantum World.
PQShield Webinar, November, 2022.Revisiting Fuzzy Signatures: Towards a More Risk-Free Cryptographic Authentication System based on Biometrics.
21th Forum on Information Technology, September, 2022.A New Simple Technique to Bootstrap Various Lattice Zero-Knowledge Proofs to QROM Secure NIZKs.
Monash Univsersity, Cybersecurity Seminars, July, 2021. (slides, video).
Workshop on Cryptography and Information Security (WCIS), September, 2021.
Design and Evaluation for New-generation Cryptography, November. 2021.Calamari and Falafl: Logarithmic (Linkable) Ring Signatures from Isogenies and Lattices.
ENS de Lyon/Royal Holloway/CWI Cryptography Seminar, March, 2021. (slides).Compact NIZKs from Various Assumptions.
MPI/RUB Seminar, December, 2020. (slides).Exploring Constructions of Compact NIZKs from Various Assumptions.
Workshop on Cryptography and Information Security (WCIS), September, 2019. (slides).
Exploring Links Between Lattice-based NIZKs and Various Signature Schemes (in the Standard Model).
The Workshop on Modern Trends in Cryptography, June, 2019. (slides).
On the Untapped Potential of Encoding Predicates by Arithmetic Circuits and Their Applications.
NTT-JFLI-U.Tokyo Workshop on Cryptography, January, 2018.
Tokyo Crypto Day, March, 2018. (slides).
ISEC, May, 2018.
Lattice IBE without Reduction Loss in the Random Oracle Model.
SCIS/CSS Invited Session in IWSEC, September, 2016.
研究活動
プログラム委員
国際会議・ジャーナル査読
CRYPTO, EUROCRYPT, ASIACRYPT, TCC, PKC, AsiaCCS, ACNS, PQCrypto, ACISP, APKC, IWSEC, DCC, etc...
Local Organizing Committee
標準化・ガイドライン
メディア
所属
Lead Cryptography Researcher @ PQShield.
協力研究員 @ 産業技術総合研究所 (AIST)
受賞
辻井重男セキュリティ大賞, 2022．受賞論文: How to Hide MetaData in MLS-Like Secure Group Messaging: Simple, Modular, and Post-Quantum (with Keitaro Hashimoto and Thomas Prest.)
MIT Technology Review, Innovators Under 35 Japan, 2022. 日本版ウェブページ・英語版ウェブページ.
辻井重男セキュリティ優秀賞, 2022．受賞論文: A Concrete Treatment of Efficient Continuous Group Key Agreement via Multi-Recipient PKEs (with Keitaro Hashimoto, Eamonn W. Postlethwaite, Thomas Prest, Bas Westerbaan.)
電子情報通信学会 暗号と情報セキュリティシンポジウム2021 (SCIS 2021), 論文賞 (received by Keitaro Hashimoto)
& 辻井重男セキュリティ優秀賞, 2021．
- 受賞論文: An Efficient and Generic Construction for Signal’s Handshake (X3DH): Post-Quantum, State Leakage Secure, and Deniable. (with Keitaro Hashimoto, Kris Kwiatkowski, Thomas Prest.)
辻井重男セキュリティ特別賞, 2021．受賞論文: Scalable Ciphertext Compression Techniques for Post-Quantum KEMs and their Applications. (with Kris Kwiatkowski, Federico Pintore, Thomas Prest.)
東京大学大学院新領域創成科学研究科長賞（博士）. 2019年5月．
Invited to Journal of Cryptography from ASIACRYPT 2018.
情報処理学会コンピュータセキュリティシンポジウム 2017 (CSS2017), 学生論文賞.
& 辻井重男セキュリティ特別賞, 2018.
- 受賞論文: On the Untapped Potential of Encoding Predicates by Arithmetic Circuits and Their Applications.
日本学術振興会特別研究員制度 (JSPS). 2017.
電子情報通信学会 暗号と情報セキュリティシンポジウム2016 (SCIS 2016), SCIS論文賞
& 辻井重男セキュリティ優秀賞, 2017.
- 受賞論文: Partitioning via Non-linear Polynomial Functions: More Compact IBEs from Ideal Lattices and Bilinear Maps. (with Shota Yamada.)