In collaboration with the Cryptography and Information Security Laboratory (CRISEC), we mainly conduct research on card-based cryptography. This field has been rapidly developing in recent years, covering topics from mathematical areas such as finite group theory, combinatorics, and formal verification to applications in education and entertainment, including puzzles and games. We are looking for students interested in cryptography, puzzles, and games. Why not join us and work on exciting research that may go down in the history of card-based cryptography?
We focus on theory of cryptography, particularly secure computation. Recently, we have been studying private simultaneous messages. We also explore size-hiding computation and secure computation with penalties. Our interests include efficiency (e.g. communication complexity and round complexity) and classifying what is possible and impossible.
Card-based cryptography is a research field that realizes cryptographic techniques using physical cards. In this field, secure computation and zero-knowledge proofs have been studied actively. For secure computation, AND protocols have been extensively studied. For zero-knowledge proofs, there has also been a major breakthrough in zero-knowledge proof protocols for Sudoku.
In recent years, the collaboration between card-based cryptography and mathematics has been deepening. For example, problems related to card shuffling naturally lead to the concept of cyclic factorization of finite groups. The question of which groups admit a cyclic factorization is mathematically intriguing. Additionally, connections with combinatorics on words and association schemes are also being actively explored.
The fusion of card-based cryptography and games is a relatively new and unexplored research area. By applying cryptographic techniques to games, we seek to discover new ways to play and enjoy them. For example, card-based cryptography can realize virtual players in games like Old Maid, allowing small groups to simulate large-scale gameplay.
Assistant Professor, University of Tsukuba
June 23, 2025
The following paper has been accepted for presentation at UCNC 2025.
June 08, 2025
Kazumasa Shinagawa will give the following presentation at the The 55th Game Informatics Research Meeting to be held at Nishijin Plaza, Kyushu University.
June 03, 2025
The following paper has been accepted for presentation at IWSEC 2025.
May 28, 2025
Kazumasa Shinagawa will give a talk at the research workshop 産学連携と数理・暗号分野連携によるカードベース暗号の深化と新境地Ⅱ organized by the Institute of Mathematics for Industry (IMI), Kyushu University. The talk title is: Open Problems on One or Two Shuffles.
May 22, 2025
Kazumasa Shinagawa will give a talk at the research workshop New Developments in Combinatorics and Information Science organized by the Research Institute for Mathematical Sciences (RIMS), Kyoto University. The talk title is: Advances in Card-Based Zero-Knowledge Proofs for Sudoku.
May 4-8, 2025
The following paper was presented at Eurocrypt 2025 held in Madrid, Spain. The presenter was Dr. Reo Eriguchi from AIST. This paper presents improved upper bounds on the communication complexity of private simultaneous messages for symmetric functions.
May 01, 2025
Our laboratory website has been launched.
April 01, 2025
Kazumasa Shinagawa has joined the Institute of Systems and Information Engineering at the University of Tsukuba.