Birthday Bound

Problem

Return the number of random hashes needed for a roughly 50 percent chance of a collision when hashes have the given number of bits:

n ~ ceil(sqrt(2 * ln(2) * 2^bits))

This is the birthday bound that sets the security level of hash functions against collisions.

Hint

Collision resistance is only about half the hash length in bits.

case 1

in: [8]

expected: 19

case 2

in: [16]

expected: 302

case 3

in: [32]

expected: 77163

case 4

in: [64]

expected: 5056937541

Starter codePython

import math
def birthday_bound(bits):
    # Your code here
    pass

4 test cases · run your code against them in the editor