A Collision attack is a type of cryptographic attack that targets the hash function. The goal of this attack is to find two different inputs that produce the same hash output. This undermines the integrity of the hashing algorithm, as hash functions are expected to produce a unique output for each unique input.

In practical terms, if two different documents (inputs) produce the same hash value (collision), an attacker can replace a legitimate file with a malicious one without detection, assuming the system validates integrity only via the hash.

CEH v13 defines a collision attack as follows:

"A collision attack focuses on finding two different messages (M1 and M2) that produce the same hash value. This can compromise digital signatures, certificates, and other security protocols."

Reference – CEH v13 Study Guide:

Module 20: Cryptography, Section: “Hashing Algorithms and Attacks”, Subsection: “Collision Attacks”

Incorrect Options Explained:

A: Public keys are part of asymmetric encryption, not relevant to collisions.

B/C: These are incorrect descriptions; collision attacks are not about breaking hashes into parts to retrieve plaintext or private keys.

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