Question

Encipher the following emperors’ names using a Shift Cipher with the given key.

1. Pompeii, key = D. ___________
2. Vespasian, key = P. _________
3. Caligula, key = H. _________
4. Nero, key = T. _____________

Answer 1

Solution

Step 1

Convert the letters into the numbers that matches alphabet

(A=0,B=1,C=2,D=3,E=4,….Y=24,Z=25)

Step 2

Calculate

Y=(X+K) mod 26

Step 3

Now convert the Y into letter matches

a)

Pompeii, key = D

P	O	M	P	E	I	I
15	14	12	15	4	8	8

Now Key=D

D=3

P	O	M	P	E	I	I
15	14	12	15	4	8	8
3	3	3	3	3	3	3
18	17	15	18	7	11	11

Step4

	P	O	M	P	E	I	I
	15	14	12	15	4	8	8
	3	3	3	3	3	3	3
(mod 26)	18	17	15	18	7	11	11
	18	17	15	18	7	11	11

Step 5

Now convert back to letters

	P	O	M	P	E	I	I
	15	14	12	15	4	8	8
	3	3	3	3	3	3	3
(mod 26)	18	17	15	18	7	11	11
	18	17	15	18	7	11	11
	S	R	P	S	H	K	K

Therefore Answer is

SRPSHKK

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b)

Vespasian, key = P

	V	E	S	P	A	S	I	A	N
	21	4	18	15	0	18	8	0	13
key P	15	15	15	15	15	15	15	15	15
	36	19	33	30	15	33	23	15	28
(mod 26)	10	19	7	4	15	7	23	15	2
	K	U	H	E	P	H	X	P	C

Therefore Answer is

KUHEPHXPC

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c)

Caligula, key = H

	C	A	L	I	G	U	L	A
	2	0	11	8	6	20	11	0
key H	7	7	7	7	7	7	7	7
	9	7	18	15	13	27	18	7
(mod 26)	9	7	18	15	13	1	18	7
	J	H	S	P	N	B	S	H

Therefore Answer is

JHSPNBSH

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d)

Nero, key = T

	N	E	R	O
	13	4	17	14
key T	19	19	19	19
	32	23	36	33
(mod 26)	6	23	10	7
	G	X	K	H

Therefore Answer is

GXKH