Which mechanism is commonly used to ensure data integrity?

• A. Encryption
• B. Password complexity
• C. Encryption alone
• D. Hashes

Answer: (D)

Data integrity is about detecting any changes to data. A cryptographic hash function takes input data and produces a fixed-size digest that changes dramatically with any modification. Because hash values are deterministic, you can compute the hash of the original data and compare it to a stored or transmitted hash. If the data has been altered, the resulting hash will be different, signaling tampering. This makes hashes the go-to mechanism for verifying that data hasn’t been altered.

Encryption, by contrast, is aimed at keeping content secret, not verifying its integrity. Encrypting data protects confidentiality, but it doesn’t inherently reveal whether the ciphertext was changed or if the plaintext was altered after encryption. Password complexity helps with authentication, not ensuring data integrity. Using encryption alone also doesn’t provide a reliable integrity check; in practice, integrity is achieved with mechanisms like hashes, MACs, or digital signatures.