Yi-Fu Lai
Profile
Nice to meet you! I am Yi-Fu Lai hailing from Taiwan. Since October 2023, I've been working as a post-doc researcher in Eike Kiltz's lab within CASA at Ruhr-Universität Bochum. Before that, I was a mathematics PhD student at the University of Auckland, where I was fortunate to have Steven Galbraith as my advisor, starting from 2020.
(PhD Thesis: Advanced Isogeny-based Cryptosystems.)
My main research interest lies in constructing cryptosystems that are provably secure from post-quantum assumptions. In pursuit of this goal, I also enjoy exploring the limits of the cryptographic tools and doing cryptographic analysis and reductions.
Keywords: Post-quantum cryptography, isogeny cryptography, lattice cryptography, code cryptography, public-key cryptosystems; oblivious transfers, ring signatures, group signatures, blind signatures, generic proof systems, zkSNARKs, identification schemes, verifiable random functions.
If you have any questions or are interested in my research, feel free to reach out to me.
Contact
Yi-Fu.Lai [at] ruhr-uni-bochum de ; 27182818284fu.lai [at] gmail com
Conference Publication & Preprints
PKC2024. A Simpler and More Efficient Reduction of DLOG to CDH for Abelian Group Actions. Steven Galbraith, Yi-Fu Lai, Hart Montgomery. (ia.cr/2024/191)
PKC2024. Breaking Parallel ROS: Implication for Isogeny and Lattice-based Blind Signatures. Shuichi Katsumata, Yi-Fu Lai, Michael Reichle. (ia.cr/2023/1603)
Indocrypt2023. Malleable Commitments from Group Actions and Zero-Knowledge Proofs for Circuits based on Isogenies. Mingjie Chen, Yi-Fu Lai, Abel Laval, Laurane Marco, Christophe Petit. (ia.cr/2023/1710)
Crypto2023. 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. (ia.cr/2023/1239) Video
CAPYBARA and TSUBAKI: Verifiable Random Functions from Group Actions and Isogenies. Yi-Fu Lai (ia.cr/2023/182)
ACNS2023. Efficient Isogeny Proofs Using Generic Techniques. Kelong Cong, Yi-Fu Lai and Shai Levin. (ia.cr/2023/037)
PQCrypto2022. Attack on SHealS and HealS: the Second Wave of GPST. Steven Galbraith and Yi-Fu Lai. (ia.cr/2022/443) Video
Eurocrypt2022. Group Signatures and More from Isogenies and Lattices: Generic, Simple, and Efficient. Ward Beullens, Samuel Dobson, Shuichi Katsumata, Yi-Fu Lai, Federico Pintore, (ia.cr/2021/1366) Video
Collusion Resistant Revocable Ring Signatures and Group Signatures from Hard Homogeneous Spaces. Yi-Fu Lai, Samuel Dobson. (ia.cr/2021/1365)
Eurocrypt2021. Compact, Efficient and UC-Secure Isogeny-Based Oblivious Transfer. Yi-Fu Lai, Steven Galbraith, Cyprien Delpech de Saint Guilhem,(ia.cr/2020/1012) Video
Journal Article
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. Full version of [EC:BDKLP22] Open Access Link
Available Slides
"A Simpler and More Efficient Reduction of DLOG to CDH for Abelian Group Actions" @ (PKC2024 Link).
"Breaking Parallel ROS: Implication for Isogeny and Lattice-based Blind Signatures." @ (PKC2024 Link).
"CSI-Otter: Isogeny-based (Partially) Blind Signatures from the Class Group Action with a Twist and a New ROS Attack." (Leuven Isogeny Day 4 Link)
"CSI-Otter: Isogeny-based (Partially) Blind Signatures from the Class Group Action with a Twist" (Google Drive Link)
"Attack on SHealS and HealS: the Second Wave of GPST" (PQCrypto2022 Link) in PQCrypto2022
"Group Signatures and More from Isogenies and Lattices: Generic, Simple, and Efficient" (Eurocrypt2022 Link) in Eurocrypt2022
" Compact, Efficient and UC-Secure Isogeny-Based Oblivious Transfer" (Eurocrypt2021 Link) in Eurocrypt2021.
Talks/Seminars
Talk: "A Simpler and More Efficient Reduction of DLOG to CDH for Abelian Group Actions" @ PKC2024, Australia.
Talk: "Breaking Parallel ROS: Implication for Isogeny and Lattice-based Blind Signatures." @ PKC2024, Australia.
Seminar: "A Simpler and More Efficient Reduction of DLog to CDH for Abelian Group Actions" 8th March @ Ruhr-University Bochum, Germany.
Seminar: "A Simpler and More Efficient Reduction of DLog to CDH for Abelian Group Actions" 29th Feb @ Université libre de Bruxelles, Belgium.
Seminar: "CSI-Otter: Isogeny-based (Partially) Blind Signatures from the Class Group Action with a Twist and a New ROS Attack." 20th Oct @ CWI seminar, Neatherland.
Talk: "CSI-Otter: Isogeny-based (Partially) Blind Signatures from the Class Group Action with a Twist and a New ROS Attack." 13rd Oct @ KU Leuven, Belgium. (Leuven Isogeny Day 4)
Talk: "CSI-Otter: Isogeny-based (Partially) Blind Signatures from the Class Group Action with a Twist" 23rd September 2023 @ Academia Sinica, Taiwan.
Seminar: "CSI-Otter: Isogeny-based (Partially) Blind Signatures from the Class Group Action with a Twist" 23rd June 2023 @ University of Birmingham seminar, UK.
Seminar: "Isogeny-based Cryptosystems (with a Focus on Blind Signature)." 16th June 2023 @ AIST, Japan.
Talk: "Attack on SHealS and HealS: the Second Wave of GPST." @ PQCrypto2022, Online.
Talk: "Group Signatures and More from Isogenies and Lattices: Generic, Simple, and Efficient." 7th July 2022 @ IBM Zurich, Switzerland.(An Ordinary Day in Supersingularland)
Talk: "Attack on SHealS and HealS: the Second Wave of GPST." 30th June 2022 @ COSIC-KU Leuven, Belgium.
Talk: "Group Signatures and More from Isogenies and Lattices: Generic, Simple, and Efficient." 13th June 2022 @ University of Birmingham, UK.
Talk: "Group Signatures and More from Isogenies and Lattices: Generic, Simple, and Efficient." @ Eurocrypt2022, Norway.
Seminar: "Group Signatures and More from Isogenies and Lattices: Generic, Simple, and Efficient." 10th June 2022 @ CWI Amsterdam, Netherlands.
Talk: "Compact, Efficient and UC-Secure Isogeny-Based Oblivious Transfer." @ Eurocrypt2021, Croatia.
Talk: "Compact, Efficient and UC-Secure Isogeny-Based Oblivious Transfer." May 2021 @ University of Auckland.
Seminar: in a team. / Talk: more open or larger.
Research Visits
Reviews
I have been fortunate enough to visit the following institutes and departments for academic communications:
AIST, Japan: 22 May 2023 - 20 Jul 2023
IBM Research Zurich, Switzerland: 4 Jul 2022 - 22 Jul 2022
COSIC KU Leuven, Belgium: 21 Jun 2022 - 1 Jul 2022
University of Birmingham: 13 Jun 2022 - 20 Jun 2022
CWI Amsterdam, Netherlands: 3 Jun 2022 - 10 Jun 2022
I am fortunate enough to participate as a sub-reviewer for the following conferences:
Asiacrypt2021/ PQCrypto2021/ Eurocrypt2022/ Mathcrypt2022/ AsiaCCS2023/ Eurocrypt2023/ Crypto2023/ Asiacrypt2023/ Mathcrypt2023/ Eurocrypt2024