Cryptography Reference
In-Depth Information
Step 2. Use a secret key K and call the CRC-based detecting authentication
procedure in the stego-image If
j
. If the comparison for the authentication
code C
g
is then correct, proceed to the next step, otherwise, a fake stego-
image is detected.
each PV y
(g)
j
B
g;j
,
Step 3. For
and
block
apply
IPLA
to
compute
the
pattern-string
(p
1
;p
2
; ;P
m
2
t
)
in
the
IPLA.
Follow
the
sign
of
B
g;j
,
p
1
;p
2
; ;P
m
2
t
to recover the bit-string of (y
g1
;y
g2
; ;y
g8
) of in the
l
m
2
t
m
for g = 1; 2; ;
.
Step 4. Pick up f
j
and calculate PV y
(g
j
in B
g;j
, j = 1; 2; ;t. Follow
RAHA to recover the polynomial with the t pairs of (f
j
;PV y
(g
j
)
0
s, j =
1; 2; ;t.
Step 5. Call RAHA to recover the polynomial with the t pair of
(f
j
;PV y
(g
j
)
0
s, j = 1; 2; ;t. Obtain secrets S
i
;i = (g 1)t + 1; (g
1)t + 2; ; (g 1)t + (t 1).
Step 6. Combine all S
i
in order to reveal the target secret image S.
Wang et al.'s scheme with the proposed algorithms to fulll the sharing
system with the target secret high capacity and detection authentication are
sketched as shown in
Figure 15.5.
15.5 Experimental Results
Capacity and detecting authentication procedure are presented and discussed
in this section via the observations of experiments for benchmark images.
Two samples of (2; 4)-threshold and (4; 6)-threshold schemes are taken into
consideration, in order to highlight the contributions made by Wang et al.'s
proposed method.
15.5.1 Fidelity Analysis
The target secret image is shown as
Figure 15.6
(
a). The benchmarks of the
cover images are Bridge, Butterfly, Toys, and Airplane, respectively, shown in
Figures 15.6 (b) (e). The size of the target secret image is
1
4
of each cover
image mentioned above. The corresponding four stego-images are shown in
Figures 15.6 (b
0
)(e
0
) after SEDA, where the cover images still look the same
as the stego-images to the human eye. The measurements of peak signal noise
ratio (PSNR) to discriminate between cover images in Figures 15.6 (b)(e) and
stego-images in Figures 15.6 (b
0
) (e
0
) were evaluated as 43.42, 43.43, 43.41,
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