Lecture 3 - Hashing

Question 1

What is a hash?

Answer 1

Hash functions take a long input and produce a short fixed length output called a hash value or a digest

Question 2

Hash functions protect what?

Answer 2

Data integrity

Question 3

Why do we need hashing?

Answer 3

1. Used for Digital signatures
2. For file integrity verification
3. Protection of digital assets
   - Credit card transactions
   - Software updates

Question 4

What is meant by a one-way hash function?

Answer 4

1. It should be practically impossible to find the original message.
2. Given some message, we shouldn’t be able to find another message that produces the same hash.

Question 5

What is the “Collision-Resistance” property?

Answer 5

It should be difficult to find two messages with the same hash output.

Question 6

What type of attacks can be used against hash functions?

Answer 6

1. Collision attack
2. Length extension attack

Question 7

Who developed MD hash functions?

Answer 7

Ron Rivest

Question 8

SHA-1 is a ____-bit hash function

Answer 8

SHA-1 is a 160-bit hash function

Question 9

Is SHA-1 secure or insecure?

Answer 9

Insecure - broken in 2005

Question 10

What are rainbow tables?

Answer 10

A pre-generated hash values of popular passwords and or variants

Question 11

List 5 Applications of One-Way Hash Functions?

Answer 11

1. Integrity Verification
2. Password Verification
3. Trusted Timestamping
4. Message Authentication Code (MAC)
5. Blockchain and Bitcoins