Grey Level Visual Cryptography for General Access Structures

Computer Science;visual cryptography;secret sharing;cryptography

MacPherson, Lesley

University of Waterloo

关键词: Computer Science;    visual cryptography;    secret sharing;    cryptography;   

Others  :  https://uwspace.uwaterloo.ca/bitstream/10012/1126/1/la2macpherson2002.pdf

瑞士|英语

来源: UWSPACE Waterloo Institutional Repository

【 摘 要 】

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.