My Research

I’m a research scientist at NTT (Social Informatics Laboratories) in Japan. My main research area is cryptography, though I am broadly interested in information security and theoretical computer science. My research focuses on how to protect computer program while preserving its functionality, how to achieve secure computation without leaking information, and designing efficient and versatile cryptographic building blocks. More specific topics are

  • Program Obfuscation/Watermarking/Copy-Protection
  • Functional Encryption
  • Lattice-Based Cryptography
  • Quantum Cryptography

Recent activities

  • Feb. 2023. A paper on public key encryption with secure key leasing was accepted by Eurocrypt 2023.
  • Dec. 2022. Invited to be a program committee member of ACM CCS 2023.
  • Sep. 2022. A paper on functional encryption with secure key leasing on ePrint archive and arXiv.

Contact Information

  • Please send official invitation mails (PC members, talks, etc.) to
    firstname dot lastname dot zk at hco dot ntt dot co dot jp (firstname = ryo)
  • For other mails:
    1. firstname at lastname dot info
    2. firstname dot lastname at gmail dot com
  • Address: NTT Corporation
    3-9-11 Midoricho, Musashino-shi, Tokyo 180-8585 Japan

Short Bio.

On pronunciation of my first name

I do not know English words whose pronunciation are exactly the same as that of Ryo. The pronunciation of Rio, which is the name of a city in Brazil, is similar to that of Ryo.