What is the difference between encryption and hashing?

• A. Encryption is reversible with a key; hashing is one-way; hashing is used for integrity and password storage with salting.
• B. Hashing is reversible with a key; encryption is one-way.
• C. Both encryption and hashing are reversible with the same key.
• D. Encryption is reversible with a key; hashing is one-way; hashing is used for integrity and password storage with salting.

Answer: (D)

Encryption protects confidentiality by turning plaintext into ciphertext using an algorithm and a key, and it can be reversed to recover the original data with the right key. Hashing, on the other hand, produces a fixed-length digest from input data in a one-way process with no key, so the original data can’t be recovered from the hash. This makes hashing ideal for integrity checks and for storing passwords: you store the hash (often with a salt) rather than the actual password, and you verify by comparing hashes rather than decrypting anything. Salting adds randomness to each password before hashing to defend against precomputed attacks. The other descriptions mix up reversibility or the need for a key, which doesn’t fit how hashing works.