Cryptography Reference
In-Depth Information
FIGURE 10.1
Visual cryptography.
chooses one of the matrices from C
0
, and to share a black pixel, the dealer
randomly chooses one of the matrices from C
1
. The chosen matrix determines
the m subpixels in each one of the n transparencies. Figure 10.1 shows the
basic concept of visual cryptography.
Definition 1 A solution to the k-out-of-n VC consists of two collections
C
0
and C
1
of n m base matrices. The solution is considered valid if the
following conditions are met:
Contrast conditions:
1. For any matrix S
0
in C
0
, the "or" V of any k of the n rows satises H(V )
dm.
2. For any matrix S
1
in C
1
, the "or" V of any k of the n rows satises H(V )
d.
Security condition:
3. For any subset fi
1
;i
2
;:::;i
q
g of f1; 2;:::;ng with q < k, the two collections
D
0
;D
1
of qm matrices obtained by restricting each nm matrix in C
0
;C
1
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