Which statement distinguishes encryption, hashing, and authentication with a simple example?

• A. Encryption hides content using a key; hashing yields a fixed digest for integrity; authentication verifies identity (e.g., login credentials).
• B. Hashing hides content using a key; encryption yields a fixed digest; authentication verifies identity.
• C. Encryption yields a fixed digest; hashing hides content; authentication proves identity.
• D. Authentication hides content; encryption protects data; hashing verifies identity.

Answer: (A)

The question is testing how encryption, hashing, and authentication each serve a different purpose in security, and how a simple example can illustrate that difference. The best statement maps each term to its real function: encryption hides content by transforming it with a key, hashing produces a fixed-size digest to check integrity, and authentication confirms who you are (for instance with login credentials).

Encryption takes readable information and turns it into unreadable ciphertext using a key. With the key, the original content can be recovered, so the goal is confidentiality—keeping data secret from anyone who doesn’t have the key. Hashing, on the other hand, runs data through a one-way function to produce a fixed-length digest. It isn’t about hiding content or making it reversible; it’s about creating a compact fingerprint that can be used to detect changes or verify data hasn’t been altered. Hashes are not meant to reveal the original input. Authentication is about proving identity—checking that someone is who they claim to be, typically using credentials like a username and password.

A simple way to picture this is: lock a message with encryption so only the intended recipient with the key can read it; generate a hash of a file to ensure it hasn’t been tampered with when you later receive it; log in to a system to prove you are who you say you are. The other options mix up these roles by suggesting, for example, that hashing hides content or that encryption yields a fixed digest, which aren’t correct descriptions of what those techniques do.