Cryptography Multiple Choice Questions on “Hash Functions and Its Applications”.
1. When a hash function is used to provide message authentication, the hash function value is referred to as
a) Message Field
b) Message Digest
c) Message Score
d) Message Leap
Answer: b
Clarification: A hash function providing message authentication is referred to as massage digest.
2. Message authentication code is also known as
a) key code
b) hash code
c) keyed hash function
d) message key hash function
Answer: c
Clarification: Message authentication code is also known as keyed hash function.
3. The main difference in MACs and digital signatures is that, in digital signatures the hash value of the message is encrypted with a user’s public key.
a) True
b) False
Answer: b
Clarification: The main difference in MACs and digital signatures is that, in digital signatures the hash value of the message is encrypted with a user’s private key.
4. Case b ( refer Figure 1 From The chapter Message Authentication Codes in William Stallings )is an example of digital signature.
a) True
b) False
Answer: a
Clarification: Yes, case b is an example of digital signature as the hash value of the message is encrypted with a user’s private key.
5. What is a one-way password file?
a) A scheme in which the password is jumbled and stored
b) A scheme in which the password is XOR with a key and stored
c) A scheme in which the hash of the password is stored
d) A scheme in which the password is passed through a PRF, which is then stored
Answer: c
Clarification: A scheme in which the hash of the password is stored by an operating system rather than the password itself is the one-way password file system.
6. Which one of the following is not an application hash functions?
a) One-way password file
b) Key wrapping
c) Virus Detection
d) Intrusion detection
Answer: b
Clarification: Key wrapping is a separate algorithm and not an application of hash fuctions.
7. If the compression function is collision resistant, then so is the resultant iterated hash function.
a) True
b) False
Answer: a
Clarification: The statement is true. The problem of designing a secure hash function reduces to that of designing a collision resistant compression function.
8. A larger hash code cannot be decomposed into independent subcodes.
a) True
b) False
Answer: b
Clarification: Hash codes can be decomposed into independent subcodes and this was the logic behind the meet in the middle attack.