Which concept is a small representation of a message used to ensure authentication and integrity rather than confidentiality?

• A. Privacy Shield
• B. Policy
• C. Message Digest
• D. Non-repudiation

Answer: (C)

A message digest is a fixed-size fingerprint of a message produced by a hash function. It is used to verify that the data hasn’t been altered, which gives you integrity. When you pair the digest with a digital signature or a secret key, you can also verify who generated it, which adds authentication. Importantly, a digest does not hide the message content, so it does not provide confidentiality. That’s why this concept best fits a small representation of a message used to ensure authentication and integrity rather than confidentiality. The other terms relate to privacy, policy, or non-repudiation rather than a compact data representation used for integrity checks.