# Encrypt the Plaintext Below Using the Caesar Cipher

**Topics:**Cryptography, E-mail, Transport Layer Security

**Pages:**25 (1667 words)

**Published:**December 14, 2010

Exercise

1:

Encrypt the plaintext below using the Caesar cipher: THE CAESAR CIPHER IS A TYPICAL EXAMPLE OF A SUBSTITUTION CRYPTOSYSTEM.

t

19

22

w

a 0 n 13

b 1 o 14

c 2 p 15

d 3 q 16

e 4 r 17

f 5 s 18

g 6 t 19

h 7 u 20

i 8 v 21

j 9 w 22

k 10 x 23

l 11 y 24

m 12 z 25

Encryption

formula:

f(x)= x+k (mod26) Character to be shifted to the right by k; x is the characterʼs numerical equivalent. h

7

10

k

e

4

7

h

c

2

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u

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23

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a

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3

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1

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h

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s

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t

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r

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u

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u

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23

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p

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t

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h

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k

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r

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n

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p

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p

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1

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l

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x

23

0

a

e

4

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h

a

0

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d

m

12

15

p

p

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18

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l

11

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o

e

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o

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f

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a

0

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i

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t

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t

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m

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p

WKHFDHVDUFLSKHULVDWBSLFDOHADPSOHRIDVXEVWLWXWLRQFUBSWRVBVWHP

Ciphertext:

WKH

FDHVDU

FLSKHU

LV

D

WBSLFDO

HADPSOH

RI

D

VXEVWLWXWLRQ

FUBSWRVBVWHP

1

Exercise

2

1) How would you test a piece of cipertext to determine quickly if it was the likely results of a transposition? If we know the key (shift), the formula f(x)=x-k (mod26) can be used ; x being the encrypted value.

w

22

19

t

v

21

18

s

k

10

7

h

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