Cryptography Reference
In-Depth Information
TABLE 7.5
Light transmissions of the corresponding
pixels in
Table 7.3.
b
t
(r
1
)
t
(a
1
)
t
(r
2
)
t
(a
2
)
t
(r
3
)
0
1/2
1/2
1/2
1/2
1/2
1
1/2
1/2
1/2
1/2
1/2
t
(r
1
r
2
)
t
(r
1
r
3
)
t
(r
2
r
3
)
t
(r
1
r
2
r
3
)
1/4
1/4
1/4
1/4
1/4
1/4
1/4
0
Algorithm 5{6. Encrypting a secret image into n random grid as a set
of (n;n)-VCRG (based upon Algorithms 2 and 3, respectively)
Input: an hw binary image B and an integer n
Output: a set of n random gridsE= fR
1
;R
2
;:::;R
n
g constituting (n;n)-
VCRG of B
Algorithm 5.
1.
for (1 6 k 6 n 1) do
f generate R
k
as a random grid,
T
(R
k
) = 1=2
g
2.
for (each pixel B[i;j], 1 6 i 6 h and 1 6 j 6 w) do
2.1 f a
1
= R
1
[i;j]
2.2
for (2 6 k 6 n 1) do
f a
k
= f(R
k
[i;j];a
k1
)
g
2.3
if (B[i;j] = 0) then R
n
[i;j] = f(B[i;j];a
n1
)
( = f(0;a
n1
) = a
n1
)
else R
n
[i;j] =random pixel()
g
3.
output(R
1
;R
2
;:::;R
n
)
Algorithm 6.
1.
for (1 6 k 6 n 1) do
f generate R
k
as a random grid,
T
(R
k
) = 1=2
g
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