Cryptography Reference
In-Depth Information
O
j
] is created as follows.
The corresponding matrix [
2
4
3
5
=
2
4
3
5
O
1
O
2
O
3
O
4
O
1
O
2
O
3
O
1
O
2
O
1
O
1
O
3
O
4
O
2
O
3
O
4
O
1
O
2
O
3
O
4
O
j
]=
[
O
1
O
2
O
3
O
4
O
1
O
2
O
3
O
4
Then, four shadows S
1
, S
2
, S
3
, and S
4
are generated as follows.
S
1
= O
1
[ O
2
[ O
3
[ O
4
= O
1
[O
2
[O
3
[=O
1
[O
2
[O
3
;
S
2
= O
1
[ O
2
[ O
3
[ O
4
= O
1
[O
2
[[O
4
=O
1
[O
2
[O
4
;
S
3
= O
1
[ O
2
[ O
3
[ O
4
= O
1
[[O
3
[O
4
=O
1
[O
3
[O
4
;
S
4
= O
1
[ O
2
[ O
3
[ O
4
= [O
2
[O
3
[O
4
=O
2
[O
3
[O
4
;
15.4 Wang et al.'s Scheme
In this section, we describe in detail Wang et al.'s scheme [10] to introduce
the standard method of polynomial-based image sharing. Some notations in
Wang et al.'s scheme have been trimmed for easy description. Also, the Galois
Field GF(2
8
) operations are applied to their scheme such that the all gray-
level values 0255 can be completely represented. Therefore, the secret image
is completely lossless. The detailed approaches in Wang et al.'s scheme are
introduced in the following subsections.
15.4.1 Secret Image Sharing
Based on the study in the literature [8], a secret image sharing technique was
applied in our scheme. In their proposal, the size of shadows could be dra-
matically reduced, with n shares being embedded into n different host images
to avoid the attention of hackers. However, if malicious participants deliver
fake stego-images, the receivers may recover a fake secret image, thus mislead-
ing those participating in the secret sharing scheme, due to poor detection.
Thus, yet another secret sharing function was invented, that we also applied
in our proposal, using detection authentication to enhance security. Below,
a revised algorithm is presented to achieve both high capacity and extended
applications, where participants can recover two or more secret images from a
stego-image. The notations for the Revised Algorithm of High-Capacity and
Applications (RAHA for short) are given prior to all the steps shown.
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