1) The following questions are related to Caesar Cipher For the general Caesar a
ID: 3756170 • Letter: 1
Question
1) The following questions are related to Caesar Cipher
For the general Caesar algorithm
C = E(p) = (p + k) mod (26)
a) What is the decryption algorithm?
b) How many keys we need to try if we use a brute-force cryptanalysis
c) For the following plaintext
meet me after the toga party
What is the ciphertext if we encrypt with key 6?
d) Try to decrypt the following ciphertext
LV WKLV VHFXUH RU QRW
What is the corresponding plaintext? What is the key value?
e) Using the Vigenere cipher, encrypt the word “explanation” using the key cis.
Explanation / Answer
a) What is the decryption algorithm?
ans) p= (c - k) mod (26)
Explanation:-
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b) How many keys we need to try if we use a brute-force cryptanalysis
Ans) 0-25
Explanation:-
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c) What is the ciphertext if we encrypt with key 6?
plain text-->meet me after the toga party
Cypher-->skkz sk glzkx znk zumg vgxze
Explanation:-
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d) Try to decrypt the following ciphertext
Cypher--> LV WKLV VHFXUH RU QRW
Plain--> IS THIS SECURE OR NOT
Key=3 .
Explanation:-
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e) Using the Vigenere cipher, encrypt the word “explanation” using the key cis.
Plain text --> explanation
Key --> cisciscisci
first letter from plaintext and key=e and c
alphabet a=0 to z=25
Then here, (e+c)%26=(4+2)%26=6%26=6=g
(x+i)%26=(23+8)%26=31%26=5=F
(p+s)%26=(15+18)%26=33%26=7=h
Cypher=gfhnifcbaqv
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