Cheating prevention in visual cryptography

Chih Ming Hu, Wen-Guey Tzeng

Research output: Contribution to journalArticlepeer-review

111 Scopus citations


Visual cryptography (VC) is a method of encrypting a secret image into shares such that stacking a sufficient number of shares reveals the secret image. Shares are usually presented in transparencies. Each participant holds a transparency. Most of the previous research work on VC focuses on improving two parameters: pixel expansion and contrast. In this paper, we studied the cheating problem in VC and extended VC. We considered the attacks of malicious adversaries who may deviate from the scheme in any way. We presented three cheating methods and applied them on attacking existent VC or extended VC schemes. We improved one cheat-preventing scheme. We proposed a generic method that converts a VCS to another VCS that has the property of cheating prevention. The overhead of the conversion is near optimal in both contrast degression and pixel expansion.

Original languageEnglish
Pages (from-to)36-45
Number of pages10
JournalIEEE Transactions on Image Processing
Issue number1
StatePublished - 1 Feb 2007


  • Cheat-preventing
  • Cheating
  • Secret sharing
  • Visual cryptography

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