# Cryptography and Network Security MCQ Questions And Answers

## 21. In cryptography, what is cipher?

1. Encrypted message
2. Algorithm for performing encrption and decryption
3. Both (A) and (B)
4. Decrypted message

Explanation: In cryptography, Cipher is an algorithm for performing encrption and decryption.

## 22. In public key encryption, if A wants to send an encrypted message

1. A encrypts message using B’s public key
2. A encrypts message using his private key
3. A encrypts message using B’s private key
4. A encrypts message using his public key

Explanation: In public key encryption, if A wants to send an encrypted message, he will encrypt message using B’s public key.

## 23. Symmetric-key cryptography started thousands of years ago when people needed to exchange

1. Files
2. Packets
3. Transmission
4. Secrets

Explanation: Symmetric-key cryptography started thousands of years ago when people needed to exchange Secrets.

## 24. Which of the following is not a type of symmetric-key cryptography technique?

1. Diffie hellman cipher
2. Caesar cipher
3. Data encryption standard (DES)
4. Playfair cipher

Explanation: Diffie hellman cipher is not a type of symmetric-key cryptography technique. All other mentioned are a type of symmetric-key cryptography technique.

## 25. The man-in-the-middle attack can endanger the security of the Diffie-Hellman method if two parties are not

1. Joined
2. Authenticated
3. Submit
4. Separate

Explanation: The man-in-the-middle attack can endanger the security of the Diffie-Hellman method if two parties are not Authenticated.

Software Engineering MCQ Questions and Answers

## 26.  In a/an ________ cipher, a pair of keys is used

1. Asymmetric-key
2. Symmetric-key
3. Both (A) and (B)
4. None of the above

Explanation: In an asymmetric-key cipher, a pair of keys is used.

## 27. Cryptanalysis is used

1. To increase the speed
2. To encrypt the data
3. To find some insecurity in a cryptographic scheme
4. To make new ciphers

Explanation: Cryptanalysis is used to find some insecurity in a cryptographic scheme. So, option C is correct.

## 28. In Cryptography, when text is treated at the bit level, each character is replaced by

1. 4 bits
2. 6 bits
3. 10 bits
4. 8 bits

Explanation: In Cryptography, when text is treated at the bit level, each character is replaced by 8 bits. So, option D is correct.

## 29. Hashed message is signed by a sender using

1. His/her private key
2. His/her public key