Which type of algorithm guarantees the integrity of messages being sent, in transit, or stored?

• A. Symmetric encryption algorithms
• B. Hashing algorithms
• C. Asymmetric encryption algorithms
• D. Compression algorithms

Answer: (B)

Integrity means ensuring data hasn’t been altered while it’s moving or stored. Hashing algorithms create a fixed-length fingerprint, or digest, from the entire message. This digest is highly sensitive to any change—even flipping a single bit produces a completely different digest. By computing the hash on the sender’s side and again on the receiver’s side (or by comparing to a published/expected digest), you can detect tampering or corruption. That’s why hashing is the type of algorithm most closely associated with guaranteeing integrity: it provides a reliable way to verify that the content remains unchanged.

Encryption, whether symmetric or asymmetric, mainly protects confidentiality. It can support integrity when combined with authentication mechanisms (like MACs or digital signatures), but the fundamental mechanism that lets you detect any alteration in transit or storage is hashing. Compression doesn’t address integrity at all; it’s about reducing size. A practical example is comparing a downloaded file’s hash to the known-good hash you’re provided; a match means the file hasn’t been altered.