1. What is the effectiveness of an n-bit hash value?
2. What is the effectiveness of a 128 bit hash value?
3. We define collision as: A collision occurs if we have x=y and H(x) = H(y).
4. Consider the following properties
Variable Input size
Fixed Output size
Pre image resistant
Second Pre image Resistant
A has function that satisfies the first _______ properties in the above table is referred to as a weak hash function.
5. The second pre-image resistant property is
a) It is computationally infeasible to find any pair (x, y) such that H(x) = H(y)
b) For any given block x, it is computationally infeasible to find y not equal to x, with H(y) = H(x)
c) For any given hash value h it is computationally infeasible to find y such that H(y) = h
d) None of the mentioned
6. A function that is second pre-image resistant is also collision resistant.
7. For an m-bit value, the adversary would have to try ____________ values to generates a given hash value h.
d) (2m) – 1
8. For an m bit hash value, if we pick data blocks at random we can expect to find two data blocks with the same hash value within ____ attempts.
d) (2m) – 1
9. Which attack requires the least effort/computations?
b) Second Pre-image
d) All required the same effort