Bio

I am researching cryptography, privacy-enhancing technologies and information security as a Senior Research Scientist at J.P. Morgan AI Research & AlgoCRYPT Center of Excellence. Prior to joining JPM, I was a member of ZK-Lab and Senior Research Associate in the Security and Privacy group at the University of Edinburgh, hosted by Markulf Kohlweiss. Some of my previous projects were supported by Protocol Labs Postdoc Fellowship. Previously, I was a short-term postdoc researcher in the Cryptography and Security group at Aarhus University, where I also studied for a PhD degree under the supervison of Claudio Orlandi and Diego F. Aranha. Before coming to Aarhus, I was a master's student at Kyoto University and a long-term research intern at NTT Corporation under Masayuki Abe, Tatsuaki Okamoto and Mehdi Tibouchi. In 2021, I was a research intern in the Security and Cryptography group at Microsoft Research Redmond under Greg Zaverucha and a visiting PhD student at University of Washington hosted by Stefano Tessaro.

My research interests revolve around both theoretical and practical aspects of digital signatures and zero-knowledge proofs.

Manuscripts / Peer-reviewed Workshop Papers

[1] Non-Interactive and Publicly Verifiable Zero Knowledge Proof for Fair Decision Trees.
Elisaweta Masserova, Antigoni Polychroniadou, Akira Takahashi.
The 2nd Workshop on Regulatable ML @NeurIPS2024

Publications

Except for [1] the list of authors is sorted alphabetically, following the American Mathematical Society's 2004 culture statement on coauthorship.

[19] Fiat-Shamir Bulletproofs are Non-Malleable (in the Random Oracle Model). [ePrint]
Chaya Ganesh, Claudio Orlandi, Mahak Pancholi, Akira Takahashi, and Daniel Tschudi.
Journal of Cryptology. Full version of [8] with improved results.

[18] Ringtail: Practical Two-Round Threshold Signatures from Learning with Errors. [ePrint]
Cecilia Boschini, Darya Kaviani, Russell W. F. Lai, Giulio Malavolta, Akira Takahashi, Mehdi Tibouchi.
IEEE S&P 2025.

[17] The Brave New World of Global Generic Groups and UC-Secure Zero-Overhead SNARKs [ePrint]
Jan Bobolz, Pooya Farshim, Markulf Kohlweiss, Akira Takahashi.
TCC 2024.

[16] CaSCaDE: (Time-Based) Cryptography from Space Communications DElay. [ePrint]
Carsten Baum, Bernardo David, Elena Pagnin, and Akira Takahashi.
SCN 2024.

[15] Aggregating Falcon Signatures with LaBRADOR. [ePrint]
Marius A. Aardal, Diego F. Aranha, Katharina Boudgoust, Sebastian Kolby, Akira Takahashi.
CRYPTO 2024.

[14] Verifiable Encryption from MPC-in-the-Head [ePrint] [video] [code]
Akira Takahashi and Greg Zaverucha.
IACR Communications in Cryptology, Volume 1, Issue 1. 2024.
Preliminary version presented at TPMPC 2022

[13] How to Compile Polynomial IOP into Simulation-Extractable SNARKs: A Modular Approach. [ePrint]
Markulf Kohlweiss, Mahak Pancholi, and Akira Takahashi.
TCC 2023.

[12] Sequential Half-Aggregation of Lattice-Based Signatures. [ePrint] [slides]
Katharina Boudgoust and Akira Takahashi.
ESORICS 2023.

[11] Witness-Succinct Universally-Composable SNARKs [ePrint] [video (by Mahak)] [slides]
Chaya Ganesh, Yashvanth Kondi, Claudio Orlandi, Mahak Pancholi, Akira Takahashi, and Daniel Tschudi.
EUROCRYPT 2023

[10] MuSig-L: Lattice-based Multi-Signature with Single-Round Online Phase [ePrint] [video] [slides]
Cecilia Boschini, Akira Takahashi, and Mehdi Tibouchi.
CRYPTO 2022

[9] Mitaka: A simpler, parallelizable, maskable variant of Falcon. [ePrint] [video (by Thomas Espitau)] [slides]
Thomas Espitau, Pierre-Alain Fouque, François Gérard, Mélissa Rossi, Akira Takahashi, Mehdi Tibouchi, Alexandre Wallet, and Yang Yu.
EUROCRYPT 2022
Preliminary versions, ETTW21 and FGRY21, appeared at the 3rd NIST PQC Standardization Conference.

[8] Fiat–Shamir Bulletproofs are Non-Malleable (in the Algebraic Group Model). [ePrint] [video (by Mahak Pancholi)] [slides]
Chaya Ganesh, Claudio Orlandi, Mahak Pancholi, Akira Takahashi, and Daniel Tschudi.
EUROCRYPT 2022

[7] ECLIPSE: Enhanced Compiling method for Pedersen-committed zkSNARK Engines. [ePrint] [video (long) by Matteo Campanelli] [video (short) by Matteo] [slides]
Diego F. Aranha, Emil Madsen Bennedsen, Matteo Campanelli, Chaya Ganesh, Claudio Orlandi, Akira Takahashi.
PKC 2022

[6] Side-channel protections for Picnic signatures. [ePrint] [code] [video (long) w/ Okan Seker] [video (short) by Okan] [slides]
Diego F. Aranha, Sebastian Berndt, Thomas Eisenbarth, Okan Seker, Akira Takahashi, Luca Wilke, and Greg Zaverucha.
CHES 2021
Preliminary version appeared at the 3rd NIST PQC Standardization Conference.

[5] Two-round n-out-of-n and Multi-Signatures and Trapdoor Commitment from Lattices. [ePrint] [video (short)] [video (long)] [slides]
Ivan Damgård, Claudio Orlandi, Akira Takahashi, and Mehdi Tibouchi.
PKC 2021 Journal of Cryptology (Invited!)

[4] LadderLeak: Breaking ECDSA with Less than One Bit of Nonce Leakage. [ePrint] [code] [Constant time patch for OpenSSL] [slides] [poster]
Diego F. Aranha, Felipe Rodrigues Novaes, Akira Takahashi, Mehdi Tibouchi and Yuval Yarom.
ACM CCS 2020

[3] Security of Hedged Fiat-Shamir Signatures under Fault Attacks. [ePrint] [overview] [slides] [video (short)] [video (full)]
Diego F. Aranha, Claudio Orlandi, Akira Takahashi and Greg Zaverucha.
EUROCRYPT 2020

[2] Degenerate Fault Attacks on Elliptic Curve Parameters in OpenSSL. [ePrint] [slides]
Akira Takahashi and Mehdi Tibouchi.
IEEE EuroS&P 2019

[1] New Bleichenbacher Records: Fault Attacks on qDSA Signatures. [ePrint] [code] [slides] [video]
Akira Takahashi, Mehdi Tibouchi, and Masayuki Abe.
CHES 2018

Program Committee Member

ICMS Workshop on Foundations and Applications of Zero-Knowledge Proofs (co-organizer), ASIACRYPT 2024, PPML 2023, ACM CCS 2023, PKC 2023, ACNS 2023, CHES 2023 Artifact Evaluation, ACM CCS 2022, CHES 2021 Artifact Evaluation

Selected Talks

[10] Aggregation and Thresholdization of PQ Signatures
A thematic trimester program at Institut Henri Poincaré on post-quantum cryptography: Deployment of Post-quantum Cryptography , Paris, France. October 2024. [slides]

[9] Zero Knowledge Proofs: Technical Challenges, Applications, and Real-world Deployment.
Joint talk with Tjerand Silde.
NIST Workshop on Privacy-Enhancing Cryptography 2024 (WPEC 2024) [slides]

[8] Side-channel protections for Picnic Signatures.
Joint talk with Okan Seker.
NIST PQC Standardization Conference. 2021. [slides] [video]

[7] Lattice-based distributed signing protocols from the Fiat--Shamir with aborts paradigm.
Seminar at Monash University Cybersecurity group, Online. October 2020. [video]
NIST Workshop on Multi-Party Threshold Schemes 2020, Online. November 2020. [slides]

[6] LadderLeak: Breaking ECDSA with Less than One Bit of Nonce Leakage.
Joint talk with Diego F. Aranha.
WAC3: Workshop on Attacks in Crypto, Online. August 2020. [video (short)] [video (full)]
DEF CON Crypto & Privacy Village, Online. August 2020.
Black Hat Europe 2020, Online. December 2020.
Real World Crypto 2021, Online. January 2021. [slides] [video]

[5] Security of Hedged Fiat-Shamir Signatures under Fault Attacks.
Workshop on Cryptography and Information Security 2020, Online. September 2020.

[4] Attacks and Countermeasures against Randomness Failure in Fiat-Shamir-type Signatures.
Seminar at Crypto and Security Group , Lund University, Sweden. January 2020.

[3] Degenerate Fault Attacks on Elliptic Curve Parameters in OpenSSL.
Seminar at Security and Cryptography Group, Microsoft Research, USA. August 2019.

[2] New Bleichenbacher Records: Fault Attacks on qDSA Signatures.
Seminar at ALMASTY Group, LIP6, Sorbonne Université, France. September 2018.
Tokyo Crypto Day, Japan. October 2018.

[1] Application of the Singular Curve Point Decompression Attack to the Bitcoin Curve.
IEICE ISEC. July 2018.

Thesis

[3] Cryptography from Zero Knowledge: Advanced Security and New Constructions. [PDF] [slides]
PhD thesis. Aarhus University. 2022.

[2] A Study on Attacks against Nonces in Schnorr-like Signatures. [PDF]
Master's thesis. Kyoto University. 2018.

[1] Efficient Decentralized Routing in Friend-to-friend Networks.
Bachelor's thesis. Kyoto University. 2017.

Teaching

Co-supervising Bachelor's Project in Computer Science, Spring 2021, Aarhus University.
TA at Cryptologic Protocol Theory, Spring 2020 & 2021, Aarhus University.
TA at Distributed Systems and Security, Fall 2019, Aarhus University.

Links

IACR ePrint Archive
Abe-Tibouchi Lab., Kyoto University
Aarhus Crypto Seminar