He received Ph.D. degrees in electronics from the University of Tokyo, Japan, in 1997. He is currently a Professor at Institute of Industrial Science, the University of Tokyo. His research interests include cryptography, network security, and security management such as security economics. He has been serving as an editorial board member of Designs, Codes and Cryptography, a competitive journal in cryptography. He also is the first Asian member of the steering committee of the Workshop on the Economics of Information Security, a leading conference in security economics. He served as a guest editor of the special issue on cloud security, IEEE Transactions on Cloud Computing, in 2014. He is a Fellow of IPSJ (Information Processing Society of Japan), and a senior member of ACM, IEEE, and IEICE. He is a member of IACR. He chaired SIG-CSEC (special interest group of computer security) and SIG-SPT (security psychology and trust) of IPSJ. He is currently a vice president of JSSM (Japan Society of Security Management).