- 2016/06 - 現在 National Institute of Advanced Industrial Science and Technology
- 2006/09 - 現在 日本学術会議連携会員
- 2006/04 - 現在 Professor, Graduate School of Environment and information Sciences, Yokohama National University
- 2013/04 - 2016/03 Japan Society for the Promotion of Science Recearch Center for Science Systems, Researcher
- 2005/08 - 2012/03 Advisor, Research Center for Information Security, National Institute of Advanced Industrial Science and Technology
- 2001/04 - 2006/03 Professor, Graduate School of Environment and information Sciences, Yokohama National University
- 2001/04 - 2006/03 Researcher, Institute of Industrial Sciences, The University of Tokyo
- 2001/03 - Professor, Faculty of Engineering
- 1998/04 - 2001/02 Associate Professor, Graduate School of Engineering
- 1995/09 - 2000/09 Sub Leader, Research Project on Information Communication Security Technologies, Telecommunication Advancement Organization
- 1989/11 - 1998/03 Associate Professor, Faculty of Engineering, Yokohama National University
- 1996/03 - 1996/05 Visiting Scientist, Issac Newton Institute of Mathematical Sciences, Cambridge University, U.K.
- 1994/04 - 1994/08 Visiting Professor, University of Karlsruhe
- 1990/04 - 1992/04 Visiting Scholar, Institute of Monetary and Economic Studies, The Bank of Japan
- 1986/04 - 1989/10 Lecturer, Faculty of Engineering, Yokohama National University
- 1985/10 - 1986/03 日本学術振興会 特別研究員