Which of the following statements correctly pairs encryption, hashing, and authentication with simple examples?

• A. Encryption uses a key; hashing yields a fixed-size digest; authentication verifies identity
• B. Encryption uses a key for authentication only; hashing encrypts data; authentication is not related
• C. Hashing provides encryption of data; encryption authenticates users; authentication hashes passwords
• D. All of the above

Answer: (D)

Think about what each concept actually does: encryption uses a key to transform data so that only someone with the key can read it, providing confidentiality. Hashing takes input and produces a fixed-size digest; it’s a one-way, fast operation used for integrity checks and quick comparisons, not to reveal the original data. Authentication is about proving who you are, typically by checking credentials like passwords or tokens.

The statement that matches these roles most accurately says: encryption uses a key; hashing yields a fixed-size digest; authentication verifies identity. That captures the distinct purposes of each concept.

The other statements mix up the ideas. Encryption isn’t limited to authentication, hashing isn’t encryption, and authentication isn’t unrelated to the other concepts. Passwords are often stored as hashes for authentication, but that alone doesn’t describe how authentication and encryption relate.