A cryptographic hash function should be deterministic and produce fixed-length output.

A cryptographic hash function should be deterministic and produce fixed-length output.

• A. Deterministic and produce fixed-length output.
• B. Reversible to reveal the original data.
• C. Variable-length output with collisions guaranteed.
• D. Easily invertible.

Answer: (A)

The idea being tested is that a cryptographic hash should be deterministic and produce a fixed-length output. Deterministic means the same input always yields the same hash value, which is essential for reliably verifying data and comparing it across systems. If hashing different copies of the same data produced different results, you couldn’t trust or reuse hashes for integrity checks or detection of changes. Fixed-length output means the hash has a constant size no matter how big or small the input is. This consistency makes storage, indexing, and protocol design predictable and efficient, and it keeps processing and comparison straightforward regardless of input length. Reversibility to reveal the original data would defeat the purpose of hashing, since hashes are meant to be one-way summaries rather than reversible transformations. A variable-length output with guaranteed collisions contradicts the fixed-length requirement and undermines predictable handling and security properties. Easily invertible hashes likewise violate the one-way nature that cryptographic hashes rely on.

The idea being tested is that a cryptographic hash should be deterministic and produce a fixed-length output. Deterministic means the same input always yields the same hash value, which is essential for reliably verifying data and comparing it across systems. If hashing different copies of the same data produced different results, you couldn’t trust or reuse hashes for integrity checks or detection of changes.

Fixed-length output means the hash has a constant size no matter how big or small the input is. This consistency makes storage, indexing, and protocol design predictable and efficient, and it keeps processing and comparison straightforward regardless of input length.

Reversibility to reveal the original data would defeat the purpose of hashing, since hashes are meant to be one-way summaries rather than reversible transformations. A variable-length output with guaranteed collisions contradicts the fixed-length requirement and undermines predictable handling and security properties. Easily invertible hashes likewise violate the one-way nature that cryptographic hashes rely on.