# Computer Cryptography MCQ Question with Answer

## Computer Cryptography MCQ with detailed explanation for interview, entrance and competitive exams. Explanation are given for understanding.

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Question No : 1
In the AES-128 algorithm there are mainly __________ similar rounds and _________ round is different from other round.

5 similar rounds having 2 pair ; every alternate
9 ; the last
8 ; the first and last
10 ; no

Question No : 2
Which of the following modes of operation in DES is used for operating?

Cipher Feedback Mode (CFB)
Cipher Block chaining (CBC)
Electronic code book (ECB)
Output Feedback Modes (OFB)

Question No : 3
Using Rivest, Shamir, Adleman cryptosystem with p=7 and q=9. Encrypt M=24 to find ciphertext. The Ciphertext is:

42
93
114
103

Question No : 4
International Data Encryption Algorithm (IDEA) was developed by

Xuejia Lai and James Massey
Xuejia Lai and Bruce Schneier
Xuejia Lai and Stafford Tavares

Question No : 5
When do we compare the AES with DES, which of the following functions from DES does not have an equivalent AES function in cryptography?

f function
permutation p
swapping of halves
xor of subkey with function f

Question No : 6
Data encryption standard is a block cipher and encrypts data in blocks of size of _____ each.

16 bits
64 bits
32 bits
All of the mentioned above

Question No : 7
The process of decryption of an AES ciphertext is similar to the encryption process in the ______.

Reverse order
Next order
Both A and B
All of the mentioned above

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 Exam Name No. Of Q Attempted Link Computer set 1 30 6402 Start Computer set 2 30 2572 Start Computer set 3 30 2217 Start Computer set 4 30 2134 Start Computer set 5 30 2081 Start Computer set 6 30 2108 Start Computer set 7 30 2168 Start Computer set 8 30 2327 Start Computer set 9 30 2042 Start Computer set 10 30 2138 Start Computer set 11 30 2163 Start Computer set 12 30 2415 Start