What is a birthday attack?

A birthday attack is centered around the mathematical principle known as the birthday paradox, which relates to probability theory. This attack specifically targets weaknesses in cryptographic hash functions by exploiting the likelihood of two different inputs producing the same hash output. In essence, it does not directly attempt to guess specific passwords or manipulate data integrity but rather seeks to find collisions in the hash function.

In the context of this attack, an attacker utilizes a brute force approach to generate pairs of data that could yield matching hash values, capitalizing on the fact that with a relatively small number of attempts, there's a significant probability of finding two different inputs that hash to the same value. The design of Pseudorandom Number Generators (PRNGs) can also be a factor in these attacks, as weaknesses in their output may increase the chance of finding collisions effectively, illustrating why this answer aligns well with the definition of a birthday attack.