I am a research scientist at NTT, Japan. My main research area is cryptography.
Senior Distinguished Researcher at NTT Social Informatics Laboratories and NTT Research Center for Theoretical Quantum Information
Oct. 2021-present: Affiliate Associate Professor at Yukawa Institute for Theoretical Physics, Kyoto University
Jan. 2020-Apr. 2021: Visiting Associate Research Scholar at Princeton University (hosted by Prof. Mark Zhandry)
Apr. 2016-Mar. 2017 Collaborative Researcher at National Institute of Advanced Industrial Science and Technology (AIST)
Apr. 2014-Mar. 2017: JSPS Research Fellowship for Young Scientists (DC1)
Aug. 2014-Sep. 2014: Internship at NTT Secure Platform Laboratories (Mentor: Ryo Nishimaki)
Aug. 2012-Mar. 2014: Technical Staff at National Institute of Advanced Industrial Science and Technology (AIST)
Apr. 2014-Mar. 2017 Ph.D in Science, The University of Tokyo (Supervisor: Prof. Noboru Kunihiro)
Apr. 2012-Mar. 2014 Master of Science, The University of Tokyo (Supervisor: Prof. Noboru Kunihiro)
Apr. 2008-Mar. 2012 Bachelor of Science, The University of Tokyo (Major: Mathematics)
See also DBLP and Google Scholar
The order of authors is alphabetical, unless otherwise noted.
(Most works done in 2016 or earlier use non-alphabetical order, and the others use alphabetical order. )
MicroCrypt Assumptions with Quantum Input Sampling and Pseudodeterminism: Constructions and Separations
Mohammed Barhoush, Ryo Nishimaki, Takashi Yamakawa
ePrint
Anonymous Public-Key Quantum Money and Quantum Voting
Alper Çakan, Vipul Goyal, Takashi Yamakawa
presented at QIP 2025
arXiv, ePrint
Untelegraphable Encryption and its Applications
Jeffrey Champion, Fuyuki Kitagawa, Ryo Nishimaki, Takashi Yamakawa
accepted at TQC 2025
arXiv
CountCrypt: Quantum Cryptography between QCMA and PP
Eli Goldin, Tomoyuki Morimae, Saachi Mutreja, Takashi Yamakawa
arXiv, ePrint
A Note on Output Length of One-Way State Generators and EFIs
Minki Hhan, Tomoyuki Morimae, Takashi Yamakawa
arXiv
Quantum Lifting for Invertible Permutations and Ideal Ciphers
Alexandru Cojocaru, Minki Hhan, Qipeng Liu, Takashi Yamakawa, Aaram Yun
CRYPTO 2025
arXiv, ePrint
The Round Complexity of Black-Box Post-Quantum Secure Computation
Rohit Chatterjee, Xiao Liang, Omkant Pandey, Takashi Yamakawa
CRYPTO 2025
arXiv, ePrint
Non-Committing Identity based Encryption: Constructions and Applications
Rishab Goyal, Fuyuki Kitagawa, Venkata Koppula, Ryo Nishimaki, Mahesh Sreekumar Rajasree, Takashi Yamakawa
PKC 2025
Cryptographic Characterization of Quantum Advantage
Tomoyuki Morimae, Yuki Shirakawa, Takashi Yamakawa
STOC 2025
also presented at QIP 2025
arXiv, ePrint
A New World in the Depths of Microcrypt: Separating OWSGs and Quantum Money from QEFID
Amit Behera, Giulio Malavolta, Tomoyuki Morimae, Tamer Mour, Takashi Yamakawa
Eurocrypt 2025 (soft merge with this paper)
also presented at TQC 2025
arXiv, ePrint
A Simple Framework for Secure Key Leasing
Fuyuki Kitagawa, Tomoyuki Morimae, Takashi Yamakawa
Eurocrypt 2025
arXiv, ePrint
Robust Combiners and Universal Constructions for Quantum Cryptography
Taiga Hiroka, Fuyuki Kitagawa, Ryo Nishimaki, Takashi Yamakawa
TCC 2024
arXiv, ePrint
Quantum Unpredictability
Tomoyuki Morimae, Shogo Yamada, Takashi Yamakawa
Asiacrypt 2024
also presented at AQIS 2024 (short talk)
arXiv, ePrint
Exponential Quantum One-Wayness and EFI Pairs
Giulio Malavolta, Tomoyuki Morimae, Michael Walter, Takashi Yamakawa
SCN 2024
arXiv
Unconditionally Secure Commitments with Quantum Auxiliary Inputs
Tomoyuki Morimae, Barak Nehoran, Takashi Yamakawa
CRYPTO 2024 (soft merge with this paper)
also presented at QCRYPT 2024 and QIP 2025 (merged with this paper)
arXiv, ePrint
Quantum Public-Key Encryption with Tamper-Resilient Public Keys from One-Way Functions.
Fuyuki Kitagawa, Tomoyuki Morimae, Ryo Nishimaki, Takashi Yamakawa
CRYPTO 2024
also presented at QIP 2024
arXiv ePrint
Quantum Complexity for Discrete Logarithms and Related Problems
Minki Hhan, Takashi Yamakawa, Aaram Yun
CRYPTO 2024
also presented at AQIS 2023 (long talk) and TQC 2024 (talk only (merged with this paper))
arXiv, ePrint
Quantum Advantage from One-Way Functions
Tomoyuki Morimae, Takashi Yamakawa
CRYPTO 2024
also presented at QCRYPT 2023 and TQC 2024 (talk only)
arXiv ePrint
Revocable Quantum Digital Signatures
Tomoyuki Morimae, Alexander Poremba, Takashi Yamakawa
TQC 2024 (talk + proceedings)
arXiv ePrint
One-Wayness in Quantum Cryptography
Tomoyuki Morimae, Takashi Yamakawa
TQC 2024 (talk + proceedings)
arXiv, ePrint
Certified Everlasting Secure Collusion-Resistant Functional Encryption, and More
Taiga Hiroka, Fuyuki Kitagawa Tomoyuki Morimae, Ryo Nishimaki, Tapas Pal, Takashi Yamakawa
Eurocrypt 2024
arXiv ePrint
(A preliminary version appeared as Certified Everlasting Functional Encryption. arXiv)
Classical vs Quantum Advice and Proofs under Classically-Accessible Oracle
Xingjian Li, Qipeng Liu, Angelos Pelecanos, Takashi Yamakawa
ITCS 2024
arXiv
Publicly Verifiable Deletion from Minimal Assumptions.
Fuyuki Kitagawa, Ryo Nishimaki, Takashi Yamakawa
TCC 2023 (soft merge with this paper)
arXiv ePrint video
A New Approach to Post-Quantum Non-Malleability
Xiao Liang, Omkant Pandey, Takashi Yamakawa
FOCS 2023
arXiv, ePrint
Obfuscation of Pseudo-Deterministic Quantum Circuits
James Bartusek, Fuyuki Kitagawa, Ryo Nishimaki, Takashi Yamakawa
STOC 2023
also presented at QCRYPT 2023
arXiv, ePrint video (by James Bartusek)
Public Key Encryption with Secure Key Leasing
Shweta Agrawal, Fuyuki Kitagawa, Ryo Nishimaki, Shota Yamada, Takashi Yamakawa
Eurocrypt 2023
arXiv, ePrint video (by Ryo Nishimaki)
From the Hardness of Detecting Superpositions to Cryptography: Quantum Public Key Encryption and Commitments.
Minki Hhan, Tomoyuki Morimae, Takashi Yamakawa
Eurocrypt 2023
also presented at QCW 2022, QIP 2023, and AQIS 2023
arXiv, ePrint video (by Minki Hhan)
Proofs of Quantumness from Trapdoor Permutations
Tomoyuki Morimae, Takashi Yamakawa
ITCS 2023
also presented at QCW 2022
arXiv, ePrint video (by Tomoyuki Morimae)
Bounded Functional Encryption for Turing Machines: Adaptive Security from General Assumptions
Shweta Agrawal, Fuyuki Kitagawa, Anuja Modi, Ryo Nishimaki, Shota Yamada, Takashi Yamakawa
TCC 2022
ePrint video (by Anuja Modi)
Classically Verifiable NIZK for QMA with Preprocessing
Tomoyuki Morimae, Takashi Yamakawa
Asiacrypt 2022
ePrint arXiv video
Verifiable Quantum Advantage without Structure
Takashi Yamakawa, Mark Zhandry
FOCS 2022 (Invited to the SIAM Journal on Computing)
also presented at QIP 2023 (plenary talk)
arXiv, ePrint quanta magazine video1 video2 (by Mark Zhandry)
Quantum commitments and signatures without one-way functions
Tomoyuki Morimae, Takashi Yamakawa
CRYPTO 2022
also presented at QCW2022 and QIP 2023
arXiv ePrint video
Post-Quantum Simulatable Extraction with Minimal Assumptions: Black-Box and Constant-Round
Nai-Hui Chia, Kai-Min Chung, Xiao Liang, Takashi Yamakawa
CRYPTO 2022
arXiv ePrint video (by Xiao Liang)
Certified Everlasting Zero-Knowledge Proof for QMA
Taiga Hiroka, Tomoyuki Morimae, Ryo Nishimaki, Takashi Yamakawa
CRYPTO 2022
also presented at QIP 2022 (short plenary talk merged with this paper) and QCRYPT 2022
arXiv ePrint video (by Taiga Hiroka)
Secure Software Leasing from Standard Assumptions
Fuyuki Kitagawa, Ryo Nishimaki, Takashi Yamakawa
TCC 2021
arXiv ePrint video (by Ryo Nishimaki)
On the Impossibility of Post-Quantum Black-Box Zero-Knowledge in Constant Rounds
Nai-Hui Chia, Kai-Min Chung, Qipeng Liu, Takashi Yamakawa
FOCS 2021
also presented at QCRYPT 2021 and QIP 2022 (both merged with A Black-Box Approach to Post-Quantum Zero-Knowledge in Constant Rounds)
arXiv ePrint video
Quantum Encryption with Certified Deletion Revisited: Public Key, Attribute-Based, and Classical Communication
Taiga Hiroka, Tomoyuki Morimae, Ryo Nishimaki, Takashi Yamakawa
Asiacrypt 2021
QCRYPT2021, QIP 2022 (merged short plenary talk)
arXiv ePrint video (by Taiga Hiroka)
(A preliminary version appeared as Quantum Encryption with Certified Deletion: Public Key and Attribute-Based ePrint )
A Black-Box Approach to Post-Quantum Zero-Knowledge in Constant Rounds
Nai-Hui Chia, Kai-Min Chung, Takashi Yamakawa
CRYPTO 2021
also presented at QCRYPT 2021 and QIP 2022 (both merged with On the Impossibility of Post-Quantum Black-Box Zero-Knowledge in Constant Rounds)
arXiv ePrint video
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)
Classical vs Quantum Random Oracles
Takashi Yamakawa, Mark Zhandry
Eurocrypt 2021
ePrint video
(A preliminary version appeared as A Note on Separating Classical and Quantum Random Oracles. ePrint)
Adaptively Secure Inner Product Encryption from LWE
Shuichi Katsumata, Ryo Nishimaki, Shota Yamada, Takashi Yamakawa
Asiacrypt 2020.
ePrint video (by Shota Yamada)
Finding Collisions in a Quantum World: Quantum Black-Box Separation of Collision-Resistance and One-Wayness
Akinori Hosoyamada, Takashi Yamakawa
Asiacrypt 2020 (Best Paper Award)
ePrint video (by Akinori Hosoyamada)
NIZK from SNARG
Fuyuki Kitagawa, Takahiro Matsuda, Takashi Yamakawa
TCC 2020
ePrint video
Classical Verification of Quantum Computations with Efficient Verifier
Nai-Hui Chia, Kai-Min Chung, Takashi Yamakawa
TCC 2020
arXiv ePrint video (by Nai-Hui Chia)
Adaptively Secure Constrained Pseudorandom Functions in the Standard Model
Alex Davidson, Shuichi Katsumata, Ryo Nishimaki, Shota Yamada, Takashi Yamakawa
CRYPTO 2020.
ePrint video
Compact NIZKs from Standard Assumptions on Bilinear Maps
Shuichi Katsumata, Ryo Nishimaki, Shota Yamada, Takashi Yamakawa
Eurocrypt 2020
ePrint video (by Shuichi Katsumata)
Quantum Random Oracle Model with Auxiliary Input
Minki Hhan, Keita Xagawa, Takashi Yamakawa
Asiacrypt 2019.
ePrint
Adaptively Secure and Succinct Functional Encryption: Improving Security and Efficiency, Simultaneously
Fuyuki Kitagawa, Ryo Nishimaki , Keisuke Tanaka, Takashi Yamakawa
CRYPTO 2019
ePrint
Exploring Constructions of Compact NIZKs from Various Assumptions
Shuichi Katsumata, Ryo Nishimaki, Shota Yamada, Takashi Yamakawa
CRYPTO 2019
ePrint video (by Shuichi Katsumata)
Designated Verifier/Prover and Preprocessing NIZKs from Diffie-Hellman Assumptions
Shuichi Katsumata, Ryo Nishimaki, Shota Yamada, Takashi Yamakawa
Eurocrypt 2019
ePrint video (by Shuichi Katsumata)
(Tightly) QCCA-Secure Key-Encapsulation Mechanism in the Quantum Random Oracle Model
Keita Xagawa, Takashi Yamakawa
PQCrypto 2019
ePrint
Leakage-resilient Identity-based Encryption in Bounded Retrieval Model with Nearly Optimal Leakage-Ratio
Ryo Nishimaki, Takashi Yamakawa
PKC 2019
ePrint
Adaptively Single-key Secure Constrained PRFs for NC1
Nuttapong Attrapadung, Takahiro Matsuda, Ryo Nishimaki, Shota Yamada, Takashi Yamakawa
PKC 2019
ePrint
Tighter Security Proofs for GPV-IBE in the Quantum Random Oracle Model
Shuichi Katsumata, Shota Yamada, Takashi Yamakawa
Asiacrypt 2018. (Invited to Journal of Cryptology)
ePrint
Constrained PRFs for NC1 in Traditional Groups
Nuttapong Attrapadung, Takahiro Matsuda, Ryo Nishimaki, Shota Yamada, Takashi Yamakawa
CRYPTO 2018
ePrint video
Tightly-Secure Key-Encapsulation Mechanism in the Quantum Random Oracle Model
Tsunekazu Saito, Keita Xagawa, Takashi Yamakawa
Eurocrypt 2018
ePrint
Generalized Hardness Assumption for Self-bilinear Map with Auxiliary Information
Takashi Yamakawa, Goichiro Hanaoka, Noboru Kunihiro (non-alphabetical order)
ACISP 2016.
Adversary-Dependent Lossy Trapdoor Function from Hardness of Factoring Semi-smooth RSA Subgroup Moduli
Takashi Yamakawa, Shota Yamada, Goichiro Hanaoka, Noboru Kunihiro (non-alphabetical order)
CRYPTO 2016
ePrint video
A Short Fail-Stop Signature Scheme from Factoring
Takashi Yamakawa, Nobuaki Kitajima, Takashi Nishide, Goichiro Hanaoka, Eiji Okamoto (non-alphabetical order)
ProvSec 2014
Chosen Ciphertext Security on Hard Membership Decision Groups: The Case of Semi-smooth Subgroups of Quadratic Residues
Takashi Yamakawa, Shota Yamada, Koji Nuida, Goichiro Hanaoka, Noboru Kunihiro (non-alphabetical order)
SCN 2014
Self-bilinear Map on Unknown Order Groups from Indistinguishability Obfuscation and Its Applications
Takashi Yamakawa, Shota Yamada, Goichiro Hanaoka, Noboru Kunihiro (non-alphabetical order)
CRYPTO 2014. (Invited to Special Issues of Algorithmica)
ePrint video
Reducing Public Key Sizes in Bounded CCA-Secure KEMs with Optimal Ciphertext Length
Takashi Yamakawa, Shota Yamada, Takahiro Matsuda, Goichiro Hanaoka, Noboru Kunihiro (non-alphabetical order)
ISC 2013.
Partially Wildcarded Attribute-based Encryption and Its Efficient Construction
Go Ohtake, Yuki Hironaka, Kenjiro Kai, Yosuke Endo, Goichiro Hanaoka, Hajime Watanabe, Shota Yamada, Kohei Kasamatsu, Takashi Yamakawa, Hideki Imai (non-alphabetical order)
SECRYPT 2013.
Efficient Variants of the Naor-Yung and Dolev-Dwork-Naor Transforms for CCA Secure Key Encapsulation Mechanism
Takashi Yamakawa, Shota Yamada, Takahiro Matsuda, Goichiro Hanaoka, Noboru Kunihiro (non-alphabetical order)
AsiaPKC 2013.
Finding Collisions in a Quantum World: Quantum Black-Box Separation of Collision-Resistance and One-Wayness
Akinori Hosoyamada, Takashi Yamakawa
Journal of Cryptology, Volume 37, Issue 4, 2024
ePrint
Verifiable Quantum Advantage without Structure
Takashi Yamakawa, Mark Zhandry
Journal of the ACM, Volume 71, Issue 3, 2024
arXiv, ePrint
Compact NIZKs from Standard Assumptions on Bilinear Maps
Shuichi Katsumata, Ryo Nishimaki, Shota Yamada, Takashi Yamakawa
Journal of Cryptology, Volume 37, Issue 3, 2024
ePrint
NIZK from SNARGs
Fuyuki Kitagawa, Takahiro Matsuda, Takashi Yamakawa
Journal of Cryptology, Volume 36, Issue 2, 2023
ePrint
Compact Designated Verifier NIZKs from the CDH Assumption without Pairings
Shuichi Katsumata, Ryo Nishimaki, Shota Yamada, Takashi Yamakawa
Journal of Cryptology, Volume 34, 2021
(merged full version of ePrint and ePrint)
Tighter Security Proofs for GPV-IBE in the Quantum Random Oracle Model
Shuichi Katsumata, Shota Yamada, Takashi Yamakawa
Journal of Cryptology, Volume 34, 2021
ePrint
Generic Hardness of Inversion on Ring and Its Relation to Self-Bilinear Map
Takashi Yamakawa, Shota Yamada, Goichiro Hanaoka, Noboru Kunihiro (non-alphabetical order)
Theoretical Computer Science 820, 2020
ePrint
Self-Bilinear Map on Unknown Order Groups from Indistinguishability Obfuscation and Its Applications
Takashi Yamakawa, Shota Yamada, Goichiro Hanaoka, Noboru Kunihiro (non-alphabetical order)
Algorithmica 79(4), 2017
ePrint
Partially Wildcarded Ciphertext-Policy Attribute-Based Encryption and Its Performance Evaluation
Go Ohtake, Kazuto Ogawa, Goichiro Hanaoka, Shota Yamada, Kohei Kasamatsu, Takashi Yamakawa, Hideki Imai (non-alphabetical order)
IEICE Transactions 100-A(9), 2017
Efficient Key Encapsulation Mechanisms with Tight Security Reductions to Standard Assumptions in the Two Security Models
Yoshikazu Hanatani, Goichiro Hanaoka, Takahiro Matsuda, Takashi Yamakawa (non-alphabetical order)
Security and Communication Networks 9(12), 2016.
Classically Verifiable (Dual-mode) NIZK for QMA with Preprocessing
Tomoyuki Morimae, Takashi Yamakawa
QCrypt 2021 (online)
A Black-Box Approach to Post-Quantum Zero-Knowledge in Constant Rounds
Nai-Hui Chia, Kai-Min Chung, Takashi Yamakawa
QIP 2021 (online)
Bounded CCA-Secure KEM from the Computational Bilinear Diffie-Hellman Assumption.
Takashi Yamakawa, Shota Yamada, Goichiro Hanaoka, Noboru Kunihiro (non-alphabetical order)
IWSEC 2012. (Best Poster Award)
Unclonable Quantum Cryptography
Computation Kenkyu-kai (Computation Research Meeting), Tokyo, Mar. 2025 (In Japanese)
A Simple Framework for Secure Key Leasing
SCIS 2025, Kitakyushu, Jan. 2025 (In Japanese)
Kyoto Quantum Crypto Workshop, Kyoto, Oct. 2024
Revocable Quantum Digital Signatures
TQC 2024, Onna ('Okinawa), Sep. 2024
Quantum Public-Key Encryption with Tamper-Resilient Public Keys from One-Way Functions
CRYPTO 2024, Santa Barbara, Aug. 2024
Publicly Verifiable Deletion from Minimal Assumptions
TCC 2023, Taipei, Dec. 2023
Quantum Advantage and Cryptography
12th Tokei-Butsurigaku-Kondankai (Statistical Physics Casual Talk Meeting), online, Mar. 2025 (In Japanese)
10th Quantum Software Kenkyu-Happyo-Kai (Quantum Software Research Presentation Meeting), Kyoto, Oct. 2023 (In Japanese)
6th Kanazawa Angou-Riron-Benkyou-Kai (Kanazawa Cryptography Study Meeting), Kanazawa, Aug. 2023 (In Japanese)
Classical vs Quantum Advice and Proofs under Classically-Accessible Oracle
11th Tokyo Crypto Day, Dec. 2023
YITP Seminar, Kyoto, Jul. 2023
Quantum Advantage from Cryptographic Assumptions
2023 EWHA-KMS International Workshop on Cryptography, Seoul, Jul. 2023
Quantum Public-Key Encryption with Tamper-Resilient Public Keys from One-Way Functions
QIT 48, Kyoto, May. 2023 (In Japanese)
Non-uniformity and Quantum Advice in the Quantum Random Oracle Model (proxy for Qipeng Liu)
Eurocrypt 2023, Lyon, Apr. 2023
Classically Verifiable NIZK for QMA with Preprocessing
Asiacrypt 2022, Taipei, Dec. 2022
Proofs of Quantumness from Trapdoor Permutations
QCW 2022, Taipei, Dec. 2022
Verifiable Quantum Advantage Without Structure
Shonan Meeting "New Directions in Provable Quantum Advantages", Shonan, Dec. 2023
Quantum Innovation 2023, Tokyo, Nov. 2023
Theory Seminar, Taipei, May 2023
CS Seminar at CQT, online, May 2023
QIP 2023, Ghent, Jan. 2023
FOCS 2022, Denver, Nov. 2022
Third Kyoto Workshop on Quantum Information, Computation, and Foundations, online, Oct. 2022
Recent Devolpments in Complexity-based Quantum Cryptography
Mathematics of Post-Quantum Cryptography and Quantum Information, Fukuoka, Aug. 2022 video (In Japanese)
Quantum commitments and signatures without one-way functions
CRYPTO 2022, Santa Barbara, Aug. 2022
Ben-Gurion University CS Seminar, online, May 2022
On the Impossibility of Post-Quantum Black-Box Zero-Knowledge in Constant Rounds
FOCS 2021, online, Feb. 2022
Quantum Computation and Cryptography
Information Mathematics Seminar, the University of Tokyo, Tokyo, Dec. 2023 (in Japanese)
Information Mathematics Seminar, the University of Tokyo, Tokyo, Dec. 2022 (in Japanese)
ISEC Seminar, online, Nov. 2022 (in Japanese)
YITP Seminar, online, Dec. 2021 (in Japanese)
Classical vs Quantum Random Oracles.
ENS de Lyon, RHUL, and CWI Joint Online Crypto Seminar, online, Mar. 2022
Eurocrypt 2021, online, Dec. 2021
Workshop on Cryptography and Information Security 2021, online, Sep. 2021 (In Japanese)
On Post-Quantum Black-Box Zero-Knowledge in Constant Rounds
Second Kyoto Workshop on Quantum Information, Computation, and Foundation, online, Sep. 2021
QCRYPT 2021, online, Aug. 2021
A Black-Box Approach to Post-Quantum Zero-Knowledge in Constant Rounds
CRYPTO 2021, online, Aug. 2021
Classical Verification of Quantum Computations with Efficient Verification
QIT 44, online, May 2021
NIZK from SNARG
TCC 2020, online, November 2020.
UC Berkeley Crypto Seminar, online, August 2020.
Adaptively Secure Constrained Pseudorandom Functions in the Standard Model.
CRYPTO 2020, online, August 2020.
Introduction to post-quantum public key cryptography and zero-knowledge.
The 3rd YITP Quantum Information School, online, July 2020. (In Japanese)
Finding Collisions in a Quantum World: Quantum Black-Box Separation of Collision-Resistance and One-Wayness.
ENS de Lyon, RHUL, and CWI Joint Online Crypto Seminar, online, July 2021
Joint Workshop of NTT Labs (Japan) and NTT Research (USA), Kyoto, December 2019.
Theory Day in Taiwan (2019), Taipei, October 2019.
Adaptively Single-key Secure Constrained PRFs for NC1.
PKC 2019, Beijing, April 2019
Leakage-Resilient Identity-Based Encryption in Bounded Retrieval Model with Nearly Optimal Leakage-Ratio.
PKC 2019, Beijing, April 2019
Towards Ideal Self-bilinear Map.
The 5th ACM ASIA Public-Key Cryptography Workshop, June 2018 (Invited)
Tightly-Secure Key-Encapsulation Mechanism in the Quantum Random Oracle Model.
Eurocrypt 2018, Tel Aviv, May 2018
ISEC Seminar, Sapporo, July 2018 (In Japanese)
Constrained PRFs for NC1 in Traditional Groups.
Tokyo Crypto Day, Tokyo, March. 2018
CRYPTO 2018, Santa Barbara, Aug. 2018
ISEC Seminar, Tokyo, Sep. 2018 (In Japanese)
Adversary-dependent Lossy Trapdoor Function from Hardness of Factoring Semi-smooth RSA Subgroup Moduli.
CRYPTO 2016, Santa Barbara, Aug. 2016
ISEC Seminar, Hiroshima, Dec. 2016 (In Japanese)
10-th Workshop on Secure Constructions and Applications of Public Key Cryptography, Tokyo, Feb. 2017 (In Japanese)
Generalized Hardness Assumption for Self-bilinear Map with Auxiliary Information.
ACISP 2016, Melbourne, July 2016
Applications of Indistinguishability Obfuscation.
IEICE General Conference, Shiga, Mar. 2015 (In Japanese)
A Short Fail-Stop Signature Scheme from Factoring.
ProvSec 2014, Hong Kong, Oct. 2014
Chosen Ciphertext Security on Hard Membership Decision Groups: The Case of Semi-smooth Subgroups.
SCN 2014, Amalfi, Sep. 2014
Self-bilinear Map on Unknown Order Groups from Indistinguishability Obfuscation and Its Applications.
CRYPTO 2014, Santa Barbara, Aug. 2014
ISEC Seminar, Tokyo, Dec. 2014 (In Japanese)
8-th Workshop on Secure Constructions and Applications of Public Key Cryptography, Tokyo, Feb. 2015 (In Japanese)
Reducing Public Key Sizes in Bounded CCA-Secure KEMs with Optimal Ciphertext Length.
ISC 2013, Dallas, Nov. 2013
Chosen Ciphertext Secure Encryption over Semi-smooth Subgroup Revisited.
IWSEC 2013, SCIS/CSS Invited Session, Okinawa, Nov. 2013 (Invited)
Fall 2021, YITP Intensive Lecture 1 (on (quantum) cryptography) , Yukawa Institute of Theoretical Physics, Kyoto University (In Japanese)
Program Committee Member:
Cryptography:
Asiacrypt: 2021, 2022, 2023, 2025
TCC: 2023, 2024, 2025
ITC: 2023
PQCRYPTO: 2025
CFail: 2025
QCW: 2022
APKC: 2018, 2019
Quantum:
QIP: 2023
TQC: 2023, 2025
AQIS: 2025
QCRYPT: 2023, 2024, 2025
Conference Subreview : Asiacrypt, CRYPTO, Eurocrypt, PKC, TCC, ACISP, ACNS, FOCS, ISAAC, ISITA, ITC, ITCS, IWSEC, MFCS, Provsec, SCN, STOC, TQC, QCRYPT, QIP etc.
Journal Review: Designs, Codes and Cryptography, Nature Physics, Quantum, etc.
Asiacrypt 2020 Best Paper Award
for the paper: Finding Collisions in a Quantum World: Quantum Black-Box Separation of Collision-Resistance and One-Wayness (with Akinori Hosoyamada).
Dean's Award for Outstanding Achievement from Graduate School of Frontier Science (Ph.D) (top honor in the department), The University of Tokyo, March 2017.
Tsujii Shigeo Security Student Award, 2015.
for the paper: Self-bilinear Map on Unknown Order Groups from Indistinguishability Obfuscation and Its Applications (with Shota Yamada, Goichiro Hanaoka, Noboru Kunihiro, CRYPTO 2014).
Dean's Award for Outstanding Achievement from Graduate School of Frontier Science (Master) (top honor in the department), The University of Tokyo, March 2014.
SCIS Paper Award at SCIS 2013 (Japanese domestic conference).
for the paper: 素因数分解問題に基づくSemi-smooth部分群上のCCA安全な公開鍵暗号の安全性証明について (On Security Proof of CCA-Secure Public Key Encryption in Semi-Smooth Subgroups) (with Shota Yamada, Goichiro Hanaoka, Noboru Kunihiro)
IWSEC 2012 Best Poster Award.
for the poster: Bounded CCA-Secure KEM from the Computational Bilinear Diffie-Hellman Assumption (with Shota Yamada, Goichiro Hanaoka, Noboru Kunihiro)
Othello: A two-player strategy board game popular in Japan, I've been playing since 2002. I'm currently ranked 9th at World Othello Federation Ratings (March 2025).
You can learn the rule and basic strategies from a free e-book written by a former world champion Brian Rose here.
Other board games including Go, Shogi (Japanese Chess), Backgammon etc.
Listening to classical music and playing the piano.
Learning languages.