What Is a Preimage Attack in Cryptography?

A preimage attack is a cryptographic attack where an attacker attempts to reverse a one-way function, such as a hash function. Given a hash output (the image), the goal is to find the original input (the preimage) that produced it.

A strong hash function should be preimage resistant, meaning it is computationally infeasible to find the input. If a preimage attack is successful, it can compromise the security of systems like password storage or digital signatures.

This attack targets the fundamental security property of a hash function.