Tokyo Institute of Technology · Computer Science
Professor Suthee Ruangwises' research lab specializes in the design and analysis of physical zero-knowledge proof protocols for logic puzzles and combinatorial problems using everyday materials such as playing cards. The lab focuses on creating practical, human-verifiable cryptographic protocols that allow a prover to demonstrate knowledge of a solution without revealing any information, particularly in the context of pencil-and-paper puzzles like Shikaku, Five Cells, Meadows, Ball Sort Puzzle, and Makaro. A key direction involves developing general verification techniques for geometric and combinatorial constraints—such as rectangle area verification—enabling broader applications in secure, tangible computation. The lab also explores probabilistic models in matching problems, extending into random preference systems and their structural properties.
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Abstract Decomposition puzzles are pencil-and-paper logic puzzles that involve partitioning a rectangular grid into several regions to satisfy certain rules. In this paper, we construct a generic card-based protocol called printing protocol , which can be used to physically verify solutions of decompositon puzzles. We apply the printing protocol to develop card-based zero-knowledge proof protocols for two such puzzles: Five Cells and Meadows. These protocols allow a prover to physically show tha
Shikaku is a pencil puzzle consisting of a rectangular grid, with some cells containing a number. The player has to partition the grid into rectangles such that each rectangle contains exactly one number equal to the area of that rectangle. In this paper, we propose two physical zero-knowledge proof protocols for Shikaku using a deck of playing cards, which allow a prover to physically show that he/she knows a solution of the puzzle without revealing it. Most importantly, in our second protocol
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