Randomness in Visual Cryptography

  • Annalisa De Bonis
  • Alfredo De Santis
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 1770)


A visual cryptography scheme for a set \( \mathcal{P} \) of n participants is a method to encode a secret image into n shadow images called shares each of which is given to a distinct participant. Certain qualified subsets of participants can recover the secret image, whereas forbidden subsets of participants have no information on the secret image. The shares given to participants in \( X \subseteq \mathcal{P} \) are xeroxed onto transparencies. If X is qualified then the participants in X can visually recover the secret image by stacking their transparencies without any cryptography knowledge and without performing any cryptographic computation.

This is the first paper which analyzes the amount of randomness needed to visually share a secret image. It provides lower and upper bounds to the randomness of visual cryptography schemes. Our schemes represent a dramatic improvement on the randomness of all previously known schemes.


Cryptography Randomness Secret Sharing Visual Cryptography 


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Copyright information

© Springer-Verlag Berlin Heidelberg 2000

Authors and Affiliations

  • Annalisa De Bonis
    • 1
  • Alfredo De Santis
    • 1
  1. 1.Dipartimento di Informatica ed Applicazioni Università di SalernoBaronissi (SA)Italy

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