Hashing

Question 1

When is the function f: X -> Y one way?

Answer 1

A function is one way if its easy to compute but given y in Y it is difficult find an x in X with f(x) = y

Question 2

When is a function f: X -> Y weakly collision resistant?

Answer 2

If for a given X it is difficult to find x’ in X different with f(x) = f(x’)

Question 3

When is a function f: X -> Y is strongly collision resistant?

Answer 3

If it is difficult to find any x and x’ such that f(x) = f(x’)

Question 4

What are the requirements for a good cryptographic hash function?

Answer 4

A cryptographic hash function is one-way and strongly collision-resistant

Question 5

What does it mean to be weakly collision resistant?

Answer 5

A hash function is weakly collision resistant if it is difficult to find two different inputs that hash to the same output

Question 6

What does it mean to be strongly collision-resistant?

Answer 6

Strongly collision resistant means that it is computationally infeasible to find any two distinct inputs that hash to the same output

Question 7

What is MD5?

Answer 7

A cryptographic protocol used for authentication messages as well as content verification and digital signatures`

Question 8

What is SHA?

Answer 8

Secure Hashing Algorithm.

Question 9

What is hashing used for?

Answer 9

Hashing is used to generate a Message Authentication Code (MAC) that can be used to confirm that a received message is the same as the sent message