I am a research scientist at NTT, Japan. My main research area is (post-quantum) cryptography.

Current Position

• Distinguished Researcher at NTT Social Informatics Laboratories (formerly Secure Platform Laboratories) and NTT Research Center for Theoretical Quantum Information

• Oct. 2021-present: Affiliate Associate Professor at Yukawa Institute for Theoretical Physics, Kyoto University

Experience

• 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)

Education

• 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)

Publications

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. )

Preprint

• Exponential Quantum One-Wayness and EFI Pairs
  Giulio Malavolta, Tomoyuki Morimae, Michael Walter, Takashi Yamakawa

• A Note on Output Length of One-Way State Generators and EFIs
  Minki Hhan, Tomoyuki Morimae, Takashi Yamakawa
  arXiv 

• Robust Combiners and Universal Constructions for Quantum Cryptography
  Taiga Hiroka, Fuyuki Kitagawa, Ryo Nishimaki, Takashi Yamakawa
  arXiv, ePrint  

International Conferences

• Unconditionally Secure Commitments with Quantum Auxiliary Inputs
  Tomoyuki Morimae, Barak Nehoran, Takashi Yamakawa
  CRYPTO 2024 (soft merge 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. 

Journal Articles

• Verifiable Quantum Advantage without Structure
  Takashi Yamakawa, Mark Zhandry
  Journal of the ACM (to appear)
  arXiv, ePrint

• Compact NIZKs from Standard Assumptions on Bilinear Maps
  Shuichi Katsumata, Ryo Nishimaki, Shota Yamada, Takashi Yamakawa
  Journal of Cryptology (to appear)
  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. 

Posters

• 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) 

Talks  

• Publicly Verifiable Deletion from Minimal Assumptions

  • TCC 2023, Taipei, Dec. 2023

• Quantum Advantage and Cryptography

  • 10th Quantum Software Workshop, Tokyo, Oct. 2023 (In Japanese)

  • 6th Kanazawa Angou-Riron-Benkyou-Kai, Kanazawa, Aug. 2023

• Classical vs Quantum Advice and Proofs under Classically-Accessible Oracle

  • 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

• 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. 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)

Lectures

Fall 2021, YITP Intensive Lecture 1 (on (quantum) cryptography) , Yukawa Institute of Theoretical Physics,  Kyoto University (In Japanese)

Activities

Program Committee Member: TCC 2024, Qcrypt 2024, Asiacrypt 2023, TCC2023, QCRYPT2023, ITC2023, TQC2023, QIP 2023, QCW 2022, Asiacrypt 2022, Asiacrypt 2021, APKC 2019, APKC 2018

Conference Subreview : Asiacrypt, CRYPTO, Eurocrypt, PKC, TCC,
                                                        ACISP, ACNS, FOCS, ISAAC, ISITA, ITC, ITCS, IWSEC, Provsec, SCN, STOC, TQC, QCRYPT, QIP etc. 

Journal Review: Designs, Codes and Cryptography, Nature Physics, Quantum,  etc.

Awards

• 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)

Hobbies

• 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 2024).
  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.

Contact Information

takashi.yamakawa.obf@gmail.com
takashi.yamakawa@ntt.com
(The following email address also still works: takashi.yamakawa.ga@hco.ntt.co.jp )