The field of study on the fundamental and theoretical issues of computer science is known as theoretical computer science, which includes computational complexity theory, cryptology, foundation of programming languages. A lot of questions remain open in this field. Our technical activity is to find interesting questions, to invent them sometimes by ourselves, and to attempt to solve them. Specifically, cryptology is a rich source of complexity-theoretic questions on number theory or algebraic geometry. For example, we characterize the difficulty of cracking a cryptosystem.
Information security is very important as one of the fundamental techniques of communication.
Information security techniques include cryptography, digital signatures and user authentication. They are utilized in electronic money, electronic voting and various other things, which means the field of information security has close relation with our social activities. Software protection and digital watermark are also important topics in order to prevent illegal use of information. For the study of information security the notions and techniques of Cryptology, Computational Complexity, Number Theory, Information Theory, Computer Networking and several other related areas are turned to use.