What term is used to describe when hashes are not unique?

• A. Collision
• B. Encryption
• C. Hashing
• D. Integrity

Answer: (A)

The term used to describe when hashes are not unique is "collision." In the context of cryptography and data integrity, a collision occurs when two different inputs produce the same hash output. This is a critical concern because it undermines the reliability of hash functions, which are designed to produce a unique hash value for a unique input. Ensuring that a hash function minimizes the likelihood of collisions is essential for maintaining the integrity of data.

In contrast, encryption refers to the process of converting plaintext into ciphertext, which is not directly related to the uniqueness of hashes. Hashing is the act of generating hash values, but it does not inherently involve the concept of uniqueness unless collisions are considered. Integrity refers to the assurance that data is accurate and unaltered, again not specifically addressing the uniqueness of hash outputs. Therefore, collision is the correct term for situations where two different inputs yield the same hash value.