Cryptography Reference
In-Depth Information
s = F(0)
=F(x
1
)
(xx
2
)(xx
3
):::(xx
k
)
(x
1
x
2
)(x
1
x
3
):::(x
1
x
k
)
+F(x
2
)
(0 x
1
)(0 x
3
):::(0 x
k
)
(x
2
x
1
)(x
2
x
3
):::(x
2
x
k
)
+:::
+F(x
k
)
(0 x
1
)(0 x
2
):::(0 x
k1
)
(x
k
x
1
)(x
k
x
2
):::(x
k
x
k1
)
= (1)
k1
[F(x
1
)
(16.15)
x
2
x
3
:::x
k
(x
1
x
2
)(x
1
x
3
):::(x
1
x
k
)
x
1
x
3
:::x
k
(x
2
x
1
)(x
2
x
3
):::(x
2
x
k
)
+F(x
2
)
+:::
x
1
x
2
:::x
k1
(x
k
x
1
)(x
k
x
2
):::(x
k
x
k1
)
]
+F(x
k
)
16.4 Proposed Scheme
Following on the details described in the previous discussions, this section
presents a detailed and complete description of the proposed scheme. In our
scheme, a halftone image HI is created from the grayscale secret image GI,
sized HW with 8 bits per pixel, by using an error diusion technique called
EDT. The transmitted stego-image is called SI and the reconstructed grayscale
secret image is called GI
0
. The proposed scheme includes two procedures: the
first is the sharing and embedding phase, and the second is the reconstruction
and verifying phase. General flowcharts of the phases of our scheme appear in
16.4.1 Sharing and Embedding Phase
A detailed algorithm for the sharing and embedding phase is described in this
section.
Input:
The secret grayscale image GI and cover image CI.
Output:
Stego-image SI.
Step 1:
Apply the error diffusion technique (EDT) to the grayscale im-
age GI to retrieve a halftone image HI. Obviously, the width and
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