What does the use of a hash assure?

• A. Confidentiality.
• B. Non-repudiation.
• C. Integrity.
• D. Availability.

Answer: (C)

Hashes provide a fingerprint of data, which lets you verify integrity. A hash function yields a fixed-size digest that is deterministic: the same input always gives the same output, and even a tiny change to the data produces a different digest. By generating and securely storing the original hash, you can later recompute the hash of the received or stored data and compare; if they match, the data hasn’t been altered in transit or at rest, indicating integrity. Hashing does not hide what’s inside the data, so it does not ensure confidentiality. It also doesn’t bind a sender to the data or prevent denial of origin—digital signatures are used for non-repudiation. And it doesn’t address availability, which is about keeping systems and services reachable. For example, download a file with a known digest, recompute the file’s hash after download, and if it matches, the file integrity is preserved.