Shuichi Katsumata

*Please call me "Shu" for short. Pronounced exactly like "shoe".

Intro.

I'm a lead cryptography researcher at PQShield Ltd, U.K, working from Japan. Before that, I was a senior cryptography researcher at the National Institute of Advanced Industrial Science and Technology (AIST), Japan (and also a research consultant at PQShield Ltd, U.K.).

My main research topics include, but are not limited to, lattice-based (or more generally post-quantum) cryptography. I enjoy constructing and providing security analysis of cryptographic primitives/protocols such as various types of signature and encryption schemes (e.g., ring signatures, IBE/ABE), zero-knowledge proofs, and secure messaging protocols.

I'm always thrilled, excited, and motivated to discuss any interesting problems with others so please feel free to reach out to me!!

Also, PQShield is hiring so if you're interested either as a permanent researcher, post-doc, or intern, check out PQShield's career webpage or contact me directly.

Contact: shuichi.katsumata [at] pqshield.com OR shuichi.katsumata000 [at] gmail.com

Publications

Preprint

ePrint.


International Conference

2023

Real World Crypto 2023. (A version of [HKP22@CCS]. ePrint.)

2022

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.

EUROCRYPT 2022. ePrint.

2021


ACM CCS
2021. arXiv. video.

EUROCRYPT 2021. ePrint. video (by Ryo Nishimaki).

PKC 2021. ePrint. video (by Keitaro Hashimoto).

2020

ASIACRYPT 2020. ePrint. video (by Shota Yamada).

ASIACRYPT 2020. ePrint. video (by Thomas Prest).

ASIACRYPT 2020. ePrint. video (by Federico Pintore).

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.

EUROCRYPT 2020. ePrint. video (by Bogdan Ursu).

EUROCRYPT 2020. ePrint. video.

PKC 2020. ePrint. video (by Federico Pintore).

2019

CRYPTO 2019. ePrint. video.

    • 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.

EUROCRYPT 2019. ePrint. video.

    • Non-Zero Inner Product Encryption Schemes from Various Assumptions: LWE, DDH and DCR. Shuichi Katsumata, Shota Yamada.

PKC 2019. ePrint.

PKC 2019. ePrint.

2018

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. Preproceeding.

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.


Journal Articles

2023

Designs, Codes and Cryptography, 2023. Springer. To appear. (Full version of [BKP20@AC]

2022

    • Direct Computation of Branching Programs and its Applications to More Efficient Lattice-based Cryptography. Shuichi Katsumata, Toi Tomita, Shota Yamada.

Designs, Codes and Cryptography, 2022. Springer.

Journal of Cryptology, Volume 35, 2022. Springer. (Full version of [HKKP22@PKC]).

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]).

Journal of Cryptology, Volume 34, 2021. Springer. (Full version of [KYY18@AC]).

2020

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]).

Talks

    • Partitioning via Non-linear Polynomial Functions: More Compact IBEs from Ideal Lattices and Bilinear Maps.
      10th Workshop on Public Key Cryptography: Secure Constructions and Its Applications, February, 2017.
      ISEC, May, 2017. (slides).

Activities

Program Committee

External Reviewer

    • CRYPTO, EUROCRYPT, ASIACRYPT, TCC, PKC, AsiaCCS, ACNS, PQCrypto, ACISP, APKC, IWSEC, DCC, etc...

Local Organizing Committee

Affiliation

Awards

  • MIT Technology Review, Innovators Under 35 Japan, 2022. Japanese Website. English Website (coming soon).

  • Tsujii Shigeo Security Award, 2022, for the paper: How to Hide MetaData in MLS-Like Secure Group Messaging: Simple, Modular, and Post-Quantum (with Keitaro Hashimoto and Thomas Prest.)

  • Symposium on Cryptography and Information Security 2021 (SCIS 2021), Best Paper Award (received by Keitaro Hashimoto)

& Tsujii Shigeo Security Award, 2021.
- for the paper: An Efficient and Generic Construction for Signal’s Handshake (X3DH): Post-Quantum, State Leakage Secure, and Deniable. (with Keitaro Hashimoto, Kris Kwiatkowski, Thomas Prest.)

  • Tsujii Shigeo Security Award, 2021, for the paper: Scalable Ciphertext Compression Techniques for Post-Quantum KEMs and their Applications. (with Kris Kwiatkowski, Federico Pintore, Thomas Prest.)

  • Dean's Award for Outstanding Achievement from Graduate School of Frontier Science (Ph.D) (top honor in the department), The University of Tokyo. May, 2019.

  • Invited to Journal of Cryptography from ASIACRYPT 2018.

  • Computer Security Symposium 2017 (CSS2017), Best Student Paper Award.

& Tsujii Shigeo Security Award, 2018.
- for the paper: On the Untapped Potential of Encoding Predicates by Arithmetic Circuits and Their Applications.

  • Research Fellowships for Doctoral Scientists, Japan Society for the Promotion of Science (JSPS). 2017.

  • Symposium on Cryptography and Information Security 2016 (SCIS 2016), Best Paper Award.

& Tsujii Shigeo Security Award, 2017.
- for the paper: Partitioning via Non-linear Polynomial Functions: More Compact IBEs from Ideal Lattices and Bilinear Maps. (with Shota Yamada.)