Dept. Mathematics,
Faculty of Education and Integrated Arts and Sciences,
Waseda University



Theoretical Computer Science: Computational Cryptography, Computational Complexity, Randomness and Computation, Quantum Computation.

Now, the following three projects are running:
  • Cryptographic Primitive Protocols (e.g., Public-Key Encryption, Commitment, Oblivious Transfer, Zero-Knowledge Proofs/Arguments)
  • Cryptographic Pseudorandom Generators and Randomness Extractors.
  • Quantum Cryptography (especially in the computational complexity sense)
  • Secure Computation / Privacy Protection (e.g., Homomorphic Encryption, Garbled Circuits)

For more details, see here.

Publication List
(see also DBLP, ResearchGate, or MathSciNet)


  • Outstanding Paper Award, GameSec 2018 (Conference on Decision and Game Theory for Security),
    for "Perfectly secure message transmission against rational timid adversaries"
    co-authored by Maiki Fujita and Kenji Yasunaga,


  • B.Eng., Computer Science, Tokyo Institute of Technology, 1990
  • M.Eng., Computer Science, Tokyo Institute of Technology, 1992
  • Dr.Sci., Mathematical and Computing Sciences, Tokyo Institute of Technology, 2001
    • Thesis: Pseudorandomness within Public-Key Encryption Schemes

Professional Experience

  • Fujitsu Laboratories Ltd., Researcher Apr/1992-Mar/2005
    • Information Security Research and Development Project, Telecommunication Advancements Organization of Japan, Researcher Jan/1999-Sep/2000
    • ERATO Project on Quantum Computation and Information, Japan Science and Technology Agency, Researcher 2002.11-2004.9, Research Advisor Nov/2004-Sep/2005
  • Saitama University, Associate Professor Apr/2005-, Professor Apr/2015-Mar/2017
    • Waseda University, Adjunct Lecturer Apr/2006-Mar/2010
    • The Institute of Statistical Mathematics, Visiting Associate Professor Apr/2006-Mar/2009
    • LRI(Univ. Paris-Sud) & LIAFA(Univ. Paris 7), Visiting Researcher Mar/2010-Feb/2011
    • Tokyo Denki University, Adjunct Lecturer Sep/2011-
  • Waseda University, Professor Apr/2017-
    • Japan Women's University, Adjunct Lecturer Apr/2018-

Professional Activities


  • Graduated PhD Students: Kai Yuen Cheong (September 2009), Ei Mon Cho (March 2018), Tushar Kanti Saha (September 2018), Maharage Nisansala Sevwandi Perera (September 2018)
  • Current PhD Students: Lwin San

Are you interested in working with me?


  • Association for Computing Machinery (ACM)
    • Special Interest Group on Algorithms and Computation Theory (SIGACT)
  • European Association for Theoretical Computer Science (EATCS)
    • Japanese Chapter
  • International Association for Cryptographic Research (IACR)
  • IEEE
    • Computer Society
    • Information Theory Society
  • Institute of Electronics, Information and Communication Engineers (IEICE)
  • Information Processing Society of Japan (IPSJ)