A directory of Objective Type Questions covering all the Computer Science subjects. Here you can access and discuss Multiple choice questions and answers for various compitative exams and interviews.

1. In affine block cipher systems if f(m)=Am + t, what is f(m1+m2) ?
a. f(m1) + f(m2) + t
b. f(m1) + f(m2) + 2t
c. f(m1) + t
d. f(m1) + f(m2)
View Answer Report Discuss Too Difficult!
Answer: (a).f(m1) + f(m2) + t

2. In affine block cipher systems if f(m)=Am + t, what is f(m1+m2+m3) ?
a. f(m1) + f(m2) + f(m3) + t
b. f(m1) + f(m2) + f(m3) +2t
c. f(m1) + f(m2) + f(m3)
d. 2(f(m1) + f(m2) + f(m3))
View Answer Report Discuss Too Difficult!
Answer: (c).f(m1) + f(m2) + f(m3)

3. What is the number of possible 3 x 3 affine cipher transformations ?
a. 168
b. 840
c. 1024
d. 1344
View Answer Report Discuss Too Difficult!
Answer: (d).1344

4. Super-Encipherment using two affine transformations results in another affine transformation.
a. True
b. False
c. May be
d. Can't say
View Answer Report Discuss Too Difficult!
Answer: (a).True

5. If the key is 110100001, the output of the SP network for the plaintext: 101110001 is
a. 110100011
b. 110101110
c. 010110111
d. 011111010
View Answer Report Discuss Too Difficult!
Answer: (b).110101110

6. If the key is 110100001 where,
If ki=0, then S_i (x)=((1 1 0 | 0 1 1 | 1 0 0 ))x+((1 1 1))
and If ki=1, then S_i (x)=((0 1 1 | 1 0 1 | 1 0 0))x+((0 1 1))
then the output of the SP network for the plaintext: 101110001 is
a. 010110011
b. 111000011
c. 110110111
d. 010110110
View Answer Report Discuss Too Difficult!
Answer: (a).010110011

7. Confusion hides the relationship between the ciphertext and the plaintext.
a. True
b. False
c. May be
d. Can't say
View Answer Report Discuss Too Difficult!
Answer: (b).False

8. The S-Box is used to provide confusion, as it is dependent on the unknown key.
a. True
b. False
c. May be
d. Can't say
View Answer Report Discuss Too Difficult!
Answer: (a).True

9. Which of the following slows the cryptographic algorithm –

1) Increase in Number of rounds
2) Decrease in Block size
3) Decrease in Key Size
4) Increase in Sub key Generation
a. 1 and 3
b. 2 and 3
c. 3 and 4
d. 2 and 4
View Answer Report Discuss Too Difficult!
Answer: (b).2 and 3

10. DES follows
a. Hash Algorithm
b. Caesars Cipher
c. Feistel Cipher Structure
d. SP Networks
View Answer Report Discuss Too Difficult!
Answer: (c).Feistel Cipher Structure

Page 1 of 4