Hide a Liar: Card-Based ZKP Protocol for Usowan

Léo Robert, Daiki Miyahara, Pascal Lafourcade, Takaaki Mizuki

Research output: Chapter in Book/Report/Conference proceedingConference contribution


A Zero-Knowledge Proof (ZKP) protocol allows a participant to prove the knowledge of some secret without revealing any information about it. While such protocols are typically executed by computers, there exists a line of research proposing physical instances of ZKP protocols. Up to now, many card-based ZKP protocols for pen-and-pencil puzzles, like Sudoku, have been designed. Those games, mostly edited by Nikoli, have simple rules, yet designing them in card-based ZKP protocols is non-trivial. This is partly due to the fact that the solution should not be leaked during the protocol. In this work, we propose a card-based protocol for Usowan, a Nikoli game. In Usowan, for each room of a puzzle instance, there is exactly one piece of false information. The goal of the game is to detect this wrong data amongst the correct data and also to satisfy the other rules. Designing a card-based ZKP protocol to deal with the property of detecting a liar has never been done. In some sense, we propose a physical ZKP for hiding of a liar.

Original languageEnglish
Title of host publicationTheory and Applications of Models of Computation - 17th Annual Conference, TAMC 2022, Proceedings
EditorsDing-Zhu Du, Donglei Du, Chenchen Wu, Dachuan Xu
PublisherSpringer Science and Business Media Deutschland GmbH
Number of pages17
ISBN (Print)9783031203497
Publication statusPublished - 2022
Event17th Annual Conference on Theory and Applications of Models of Computation, TAMC 2022 - Virtual, Online
Duration: 2022 Sept 162022 Sept 18

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume13571 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


Conference17th Annual Conference on Theory and Applications of Models of Computation, TAMC 2022
CityVirtual, Online


  • Card-based cryptography
  • Pencil puzzle
  • Usowan
  • Zero-knowledge proof

ASJC Scopus subject areas

  • Theoretical Computer Science
  • Computer Science(all)


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