Extended visual cryptography systems
<|reference_start|>Extended visual cryptography systems: Visual cryptography schemes have been introduced in 1994 by Naor and Shamir. Their idea was to encode a secret image into $n$ shadow images and to give exactly one such shadow image to each member of a group $P$ of $n$ persons. Whereas most work in recent years has been done concerning the problem of qualified and forbidden subsets of $P$ or the question of contrast optimizing, in this paper we study extended visual cryptography schemes, i.e. shared secret systems where any subset of $P$ shares its own secret.<|reference_end|>
@article{klein2003extended,
    title={Extended visual cryptography systems},
    author={Andreas Klein and Markus Wessler},
    journal={arXiv preprint arXiv:math/0302043},
    year={2003},
    archivePrefix={arXiv},
    eprint={math/0302043},
    primaryClass={math.CO cs.IT math.IT}
}