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Cryptography Homework
SHIFT CIPHER (CAESAR CIPHER)
SHIFT
3
Units
1. Encipher “I AM CAESAR”
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
Decipher “pdwk lv ixq!” ____________________________________________________________________
2. SIMPLE KEYWORD CIPHER
KEYWORD
Write letters of the keyword on the 1st row (no repeats)
Fill in the table with the remaining letters of the alphabet
(check for 26 letters!!)
Make encryption by columns
1)
2)
3)
4)
A
B
C
D
E
F
G
H
I
J
FLORIDA
K
L
M
N
O
P
Q
R
S
T
Using the Simple Keyword Cipher and the Keyword, “Florida,” encipher SEAHORSES.
Decrypt “cfxx bhlfp os sqqg!”
_______________________________________________________________________
U
V
W
X
Y
Z
3. Using the polyalphabetic VIGENERE Cipher, and the Keyword “Lemon,” encode the
phrase, “Should I become a mathematician?”
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
l
e
m
o
n
Use the table below to complete problems 4 and 5.
τ
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
4. Using the AFFINE Cipher (mod 26) and the encryption standard: σ = 5 + 8 (mod 26), encrypt “CRYPTOGRAPHY”
Plain Text
τ
+
σ
= + (mod 26)
Cipher text
C
R
Y
P
T
O
G
R
A
P
H
Y
5. Using the AFFINE Cipher (mod 26) and the encryption standard: σ = 5 + 8 (mod 26), decrypt
“zrwuwuzaagev”
Cipher text
σ
( − )
τ = ( − ) (mod 26)
Plain Text
z
r
w
u
w
u
z
a
a
h
e
v