What process is followed in conducting a birthday attack against a digital signature?

A birthday attack exploits the mathematical properties of hash functions to find two different inputs that produce the same hash output, known as a collision. In the context of digital signatures, this means creating two different documents – one legitimate and one malicious – that yield the same hash value when processed through the same hash function.

By successfully generating these two documents, an attacker can substitute the malicious document for the legitimate one without detection, as the same hash will match the digital signature. This undermines the integrity of the signature, which relies on the uniqueness of hash outputs for different inputs.

The approach of preparing both a correct and a malicious document to match hashes is crucial to the effectiveness of the birthday attack, as it directly targets the weaknesses of the hash function being used in the signature process. The ability to create such hash collisions is central to executing the birthday attack successfully.