"Given a Hash Function H, with N Possible Outputs and a Specific

Multiple Choice

"Given a hash function H, with n possible outputs and a specific value H(x) , if H is applied to k random inputs, what must be the value of k so that the probability that at least one input y satisfies H(y) = H(x) is 0.5" is a reference to the __________ .

A) authentication code
B) collision resistant
C) big endian
D) birthday attack