Pretty Good Privacy MCQ [Free PDF] – Objective Question Answer for Pretty Good Privacy Quiz

1. Pretty good privacy (PGP) security system uses

A. Public key cryptosystem
B. Private key cryptosystem
C. Public & Private key cryptosystem
D. None of the mentioned

Answer: C

PGP uses many encryption techniques such as private key cryptosystem and also public-key cryptosystem.

 

2. Public key cryptosystem is used for the encryption of

A. Messages
B. Session key
C. Session key & Messages
D. None of the mentioned

Answer: B

A public-key cryptosystem is used for encryption of messages and a private key cryptosystem is used for encryption of messages.

 

3. For digital signatures private key cryptosystem is used.

A. True
B. False

Answer: B

The public key cryptosystem is used for the creation of digital signatures.

 

4. Data compression includes

A. Removal of redundant character
B. Uniform distribution of characters
C. Removal of redundant characters & Uniform distribution of characters
D. None of the mentioned

Answer: C

Data compression removes redundant character strings in a file and produces a more uniform distribution of characters.

 

5. PGP offers _____ block ciphers for message encryption.

A. Triple-DES
B. CAST
C. IDEA
D. All of the mentioned

Answer: D

A pretty good privacy security system offers three block ciphers for message encryption – Triple-DES, IDEA, and CAST.

 

6. Which block cipher has a key length of 128 bits?

A. IDEA
B. CAST
C. IDEA & CAST
D. None of the mentioned

Answer: C

The block cipher IDEA and CAST have a key length of 128 bits whereas Triple-DES has a key size of 168 bits.

 

7. These three ciphers can operate of ______ of plaintext and cipher text.

A. 128-bit blocks
B. 64-bit blocks
C. 256-bit blocks
D. 156-bit blocks

Answer: B

The three ciphers – Triple-DES, IDEA, and CAST can operate on 64-bit blocks of plain text and cipher text.

 

8. The key size of DES is

A. 56 bits
B. 64 bits
C. 128 bits
D. 168 bits

Answer: A

The key size of the DES algorithm is 56 bits and with Triple-DES, the message to be encrypted is run on the DES algorithm 3 times.

 

9. Which operation is used in encryption using IDEA?

A. Addition modulo 216
B. Bitwise XOR
C. Addition modulo 216 & Bitwise XOR
D. None of the mentioned

Answer: C

The arithmetic operations used in IDEA are addition modulo 216, multiplication modulo 216+1, and bit-wise XOR.

 

10. What is the key size allowed in PGP?

A. 1024-1056
B. 1024-4056
C. 1024-4096
D. 1024-2048

Answer: C

A pretty good privacy security system allows 1024 to 4096 bits of key size.

 

11. Which algorithm is used for public-key encryption?

A. RSA
B. Diffie-Hellman
C. RSA & Diffie-Hellman
D. None of the mentioned

Answer: C

The two algorithms used for public-key encryption in PGP are RSA and Diffie-Hellman algorithms.

 

12. Which should be used first to decrypt?

A. Public key
B. Private key
C. Public & Private key
D. None of the mentioned

Answer: B

The recipient should first decrypt the message using the private key and then with the public key.

 

13. The digital signature provides authentication to the

A. Sender
B. Message
C. Sender & Message
D. None of the mentioned

Answer: C

The digital signature provides authentication to both the sender and the message.

 

14. In the hash function output length is fixed.

A. True
B. False

Answer: A

In the hash function, the output length is fixed and it is easy to compute.

 

15. The hash function

A. Is collision-free
B. Has manageable collision
C. Has a high unmanageable level of collision
D. None of the mentioned

Answer: A

The hash function is collision-free and it is unfeasible that two different messages will create the same hash value.

 

16. DSA protocol is based on

A. Discrete logarithm problem
B. Continuous logarithm problem
C. Discrete & Continuous logarithm problem
D. None of the mentioned

Answer: A

The DSA algorithm uses and is based on a discrete logarithm problem.

 

17. Encryption transformations are known as

A. Diffusion
B. Confusion
C. Diffusion & Confusion
D. None of the mentioned

Answer: C

The encryption transformations were termed confusion and diffusion by Shannon.

 

18. For n input bits the number of substitution patterns are

A. 2n
B. (2n)!
C. 1/2n!
D. 2n!

Answer: B

For n input bits the total number of possible substitution or connection patterns is (2n)!.

 

19. In transposition, the plaintext letters are

A. Substituted
B. Rearranged
C. Removed
D. None of the mentioned

Answer: B

In permutation or transposition, the positions of the plaintext letters in the message are simply rearranged.

 

20. The substitution of the letters is done

A. Serially
B. Parallel way
C. Serially & Parallel way
D. None of the mentioned

Answer: B

The substitution part of the encryption scheme is performed in parallel on a small segment of the blocks.

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