Cryptography Reference
In-Depth Information
TABLE 5.6
i
r r
p i
c i
0
0
18
3
21
1
1
15
0
15
2
2
0
13
13
3
3
2
6
8
4
4
4
4
8
5
0
18
17
9
6
1
15
22
11
7
2
0
8
8
8
3
2
11
13
9
4
4
11
15
10
0
18
17
9
11
1
15
14
3
12
2
0
1
1
13
3
2
8
10
14
4
4
13
17
15
0
18
18
10
16
1
15
14
3
17
2
0
13
13
5.6
BLOCK AFFINE CIPHERS
We construct an affine transformation that maps four-letter blocks to other four-letter blocks.
We will call this a block affine cipher. Suppose we are using the numerical alphabet 00, 01,
. . . , 99, and suppose the numerals 00 through 25 represent the letters A through Z, respec-
tively. (For now, we'll just say that 26 through 99 are unassigned; the reason we've extended
the ordinary alphabet in this way will become clear soon.) The message to send (in charac-
ters) is
HOWDY DOO
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