Free Certified Blockchain Professional (CBCP) Cryptography Questions and Answers — Questions and Answers

Question 1: Divide (HAPPY)26 from (SAD)26 to get the result. We determine the quotient. –

MC
JC
LD
KD (Correct answer)

Correct answer: KD

By dividing (HAPPY)26 by (SAD)26, we get KD and MLP as the remainder.

Question 2: The remaining is equal to (11001001) divided by (100111).

110 (Correct answer)
101
111
11

Correct answer: 110

(11001001) divided by (100111) gives us (110).

Question 3: Pi in base 26 is equal to

D.DSS
D.DRS (Correct answer)
D.SQR
C.DRS

Correct answer: D.DRS

Using basic conversions, we convert to 3.1415926 as D.DRS.

Question 4: The result of multiplying "YES" by "NO" in base 26 is –

THWAE
MPJNS (Correct answer)
MPAHT
THWOE

Correct answer: MPJNS

Calculate the alphabets using base 26 after converting the letters to their corresponding values.

Question 5: Divided by (lA2F) base 16, (131B6C3) yields -

9AD (Correct answer)
BAD
DAD
1AD

Correct answer: 9AD

The following base-16 division will be used, where A-F stand for 10-15.

Question 6: The estimated calculations needed to break a six-character password using the 26-letter alphabet are as follows:

8031810176
456976
11881376
308915776 (Correct answer)

Correct answer: 308915776

The correct response is 26^6 = 308915776.

Question 7: The IC of a symmetric cipher system is 0.041. What is the size of the letter "m"?

5
2
3
1 (Correct answer)

Correct answer: 1

We may calculate m using the formula m=5, where m≈0.027n/(I_c (n-1)-0.038n+0.065).

Question 8: The C =(p+3) mod 26 Caesar Cipher is used to encrypt. A case in point is the Caesar Cipher.

Bi-alphabetic Cipher
Multi-alphabetic Cipher
Mono-alphabetic Cipher (Correct answer)
Poly-alphabetic Cipher

Correct answer: Mono-alphabetic Cipher

Mono-alphabetic ciphers, like the Caesar Cipher, only encrypt or decrypt one alphabet at a time.

Question 9: A text string is used as a key by _____________ to perform a sequence of shifts on the plain-text.

Block Cipher
Playfair Cipher
Shift Cipher
Vigenere Cipher (Correct answer)

Correct answer: Vigenere Cipher

The Vigenere Cipher uses a text string as a key and a series of shifts on the plain-text to encrypt data. In this case, the sender and the recipient agree on a single key.

Question 10: In the Playfair cipher, a key table is initially created. The plaintext is encrypted using a key table, which is a 5 by 5 grid of alphabets.

Block Cipher
Playfair Cipher (Correct answer)
Shift Cipher
Rolling Cipher

Correct answer: Playfair Cipher

In the Playfair cipher, a key table is initially created. The plaintext is encrypted using a key table, which is a 5 by 5 grid of alphabets. It is required that each of the twenty-five alphabets be distinct, and letter J is left out.

Question 11: Which letters are used the most frequently in the English language?

e,t (Correct answer)
e,i
e,o
e,a

Correct answer: e,t

These letters' relative frequency, expressed as a percentage, is e-12.702, a-8.167, t-9.056, i-6.996, and o-7.507.

Question 12: Pick one of the cipher systems listed below that is easiest to decipher using frequency analysis, going from best to worst.

Random Polyalphabetic, Playfair, Vignere
Random Polyalphabetic, Plaintext, Playfair
Random Polyalphabetic, Plaintext, Beaufort, Playfair
Random Polyalphabetic, Vignere, Playfair, Plaintext (Correct answer)

Correct answer: Random Polyalphabetic, Vignere, Playfair, Plaintext

The most resistant to frequency analysis is Random Polyalphabetic, followed by Vignere, Playfair, and Plaintext.

Question 13: We obtain the following cipher text after encrypting "thepepsiisintherefrigerator" with the Vignere Cipher System and the keyword "HUMOR."

baiuvmwuwjphfoeiyrfznydokvl
abqdnwewuwjphfvrrtrfznsdokvl
abqdvmwuwjphfvvyyrfznydokvl (Correct answer)
tbqyrvmwuwjphfvvyyrfznydokvl

Correct answer: abqdvmwuwjphfvvyyrfznydokvl

Text of the cipher: Ci = Pi + ki mod m (mod 26).

Question 14: We obtain cipher text by encrypting "cryptography" with the Vignere Cipher System and the keyword "LUCKY."

mlaaeiibljki
olaaeiibljki
nlazeiibljii
nlazeiibljji (Correct answer)

Correct answer: nlazeiibljji

Text cipher: = Ci = Pi + ki mod m (mod 26).

Question 15: The English language's Index of Coincidence is about

0.048
0.065 (Correct answer)
0.038
0.068

Correct answer: 0.065

About 0.065 is the IC for the English language.

Question 16: The IC is roughly when all letters have an equal chance of being selected.

0.038 (Correct answer)
0.048
0.035
0.065

Correct answer: 0.038

The IC is around 0.038, which is less than half of the IC for the English language if every letter has the same probability of being chosen.

Free Certified Blockchain Professional (CBCP) Cryptography Questions and Answers

Divide (HAPPY)26 from (SAD)26 to get the result.
We determine the quotient. –