Which term describes a technique that produces a fixed-size value to verify data integrity?

• A. Non-repudiation
• B. Regulations
• C. Risk
• D. Message Digest

Answer: (D)

The technique described is a cryptographic hash, commonly called a message digest. A hash function takes input data of any size and produces a fixed-length output, so no matter how big or small the data is, the digest has the same length. This fixed-size value acts as a compact “fingerprint” of the data: even a tiny change in the input yields a completely different digest, making it easy to detect tampering or corruption. In practice, you generate the digest for the original data and securely store or transmit it; later, you recompute the digest on the received data and compare the two. If they match, the data’s integrity is preserved. This concept is distinct from non-repudiation, regulations, or risk, which involve different security objectives. A message digest is typically produced by a cryptographic hash function like SHA-256, chosen for fast computation and resistance to collisions.