IFN648 | Applied Cryptography

Running head: IFN648 APPLIED CRYPTOGRAPHY
IFN648 APPLIED CRYPTOGRAPHY
Name of the Student
Name of the University
Author Note

IFN648 APPLIED CRYPTOGRAPHY 1
Ciphertext 1 – Caesar cipher:
The Caesar Cipher which is also known as shift cipher is one of the simplest and
oldest forms for encrypting and decrypting messages. The Caesar cipher is basically a
substitution cipher where each and every letters of the original message will be replaced by
another letter according to a specific letter number of shifted down or shifted up in the
alphabet. For every letters in the alphabet, the position of the letter in the alphabet will be
taken say 4 for D, and then shift the number by the key number. Say, there is a key of +4 then
D will be H as well as the similar procedure will be applied to each of the letters in the text.
1. Create a frequency analysis chart for your ciphertext (include a screenshot of this chart in
your report).
Cipher text:
pcs httbts fjxit sxhpeedxcits lwtc hwt pchltgts cd lph hwt fjxit hjgt cd bpc lxiw p igpe lwd
ldjas v
Letter table:
0 A
1 B
2 C
3 D
4 E
5 F
6 G
7 H
8 I
9 J
10 K
11 L
12 M
13 N
14 O
15 P
16 Q
17 R
18 S

IFN648 APPLIED CRYPTOGRAPHY 2
19 T
20 U
21 V
22 W
23 X
24 Y
25 Z
Analysis:
2. Refer to your frequency chart and identify the ciphertext character that most likely
represents the plaintext character ‘e’. Justify your answer.
Here in the Cipher text the percentage of T is 14.81, in the cipher text the number of T is
most.

IFN648 APPLIED CRYPTOGRAPHY 3
3. Determine the key used with the Caesar cipher. Explain how you obtained this key.
Shift +1:
obr gssasr eiwhs rwgoddcwbhsr kvsb gvs obgksfsr bc kog gvs eiwhs gifs bc aob kwhv o hfod
kvc kcizr u
Shift +2:
naq frrzrq dhvgr qvfnccbvagrq jura fur nafjrerq ab jnf fur dhvgr fher ab zna jvgu n genc jub
jbhyq t
Shift +3:
mzp eqqyqp cgufq puembbauzfqp itqz etq mzeiqdqp za ime etq cgufq egdq za ymz iuft m
fdmb ita iagxp s
Shift +4:
lyo dppxpo bftep otdlaaztyepo hspy dsp lydhpcpo yz hld dsp bftep dfcp yz xly htes l ecla hsz
hzfwo r
4. Provide the plaintext corresponding to the ciphertext you were given.