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Grey Level Visual Cryptography for General Access Structures

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la2macpherson2002.pdf (276.59 KB)

Date

2002

Authors

MacPherson, Lesley

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Publisher

University of Waterloo

Abstract

Visual cryptography, first introduced by Naor and Shamir, allows a secret (black and white) image to be encoded and distributed to a set of participants such that certain predefined sets of participants may reconstruct the image without any computation. In 2000, Blundo, De Santis, and Naor introduced a model for grey-level visual cryptography which is a generalization of visual cryptography for general access structures. Grey-level visual cryptography extends this model to include grey-scale images. Decoding is done by the human visual system. In this thesis we survey known results of grey-level visual cryptography and visual cryptography for general access structures. We extend several visual cryptography constructions to grey-level visual cryptography, and derive new results on the minimum possible pixel expansion for all possible access structures on at most four participants.

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Keywords

Computer Science, visual cryptography, secret sharing, cryptography

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URI

http://hdl.handle.net/10012/1126

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Computer Science