# Cryptography

Q1. This is an encryption/decryption key known only to the party or parties that exchange secret messages.

- e-signature
- digital certificate
- private key
- security token

Answer: 3. private key

Q2. Cryptographic hash function takes an arbitrary block of data and returns

- fixed size bit string
- variable size bit string
- both (1) and (2)
- none of the mentioned

Answer: 1. fixed size bit string

Q3. The inverse of 37 mod 49 is

- 23
- 12
- 4
- 6

Answer: 3. 4

Explanation: 37-1 mod 49 = 4

Step 1. Calculate A * B mod C for B values 0 through C-1

Step 2. The modular inverse of A mod C is the B value that makes A * B mod C = 1

Q4. This is a mode of operation for a block cipher, with the characteristic that each possible block of plaintext has a defined corresponding ciphertext value and vice versa.

- footprinting
- hash function
- watermark
- Electronic Code Book

Answer: 4. Electronic Code Book

Q5. How many primitive roots are there for 19?

- 4
- 5
- 3
- 6

Answer: 4. 6

Explanation: 2, 3, 10, 13, 14, 15 are the primitive roots of 19.

Let p be a prime. Then b is a *primitive root* for p if the powers of b,

1, b, b^2, b^3, ...

include all of the residue classes mod p (except 0).

Q6. Voice privacy in GSM cellular telephone protocol is provided by

- A5/2 cipher
- b5/4 cipher
- b5/6 cipher
- b5/8 cipher

Answer: 1. A5/2 cipher

Q7. In cryptography, the order of the letters in a message is rearranged by

- transpositional ciphers
- substitution ciphers
- both (1) and (2)
- none of the mentioned

Answer: 1. transpositional ciphers

Q8. What is data encryption standard (DES)?

- block cipher
- stream cipher
- bit cipher
- none of the mentioned

Answer: 1. block cipher

Q9. The cryptography algorithms used in S/MIME are _________.

- IDEA.
- RC4.
- RSA,DES-3.
- RC5.

Answer: 3.RSA,DES-3

Q10. In asymmetric key cryptography, the private key is kept by

- sender
- receiver
- sender and receiver
- all the connected devices to the network

Answer: 2. receiver

Subscribe us to receive more such articles updates in your email.

If you have any questions, feel free to ask in the comments section below. Nothing gives me greater joy than helping my readers!

**Disclaimer:** This tutorial is for educational purpose only. Individual is solely responsible for any illegal act.

You have made your point very nicely!!

This is nicely said!.

Kudos! An abundance of content!