A plain hash by itself proves that a message was sent by a particular person.

### Why this is right\nA plain hash can help detect whether content changed, but anyone who can change the message can also calculate a new hash. It does not establish who created the message.\n\n### The concept\nIntegrity checks detect modification. Authentication requires evidence tied to an identity, such as a digital signature that a recipient verifies with the sender's public key, or a configured pre-shared key used to authenticate VPN peers.\n\n### The other options\n- **True**: this confuses detecting change with proving the sender's identity.\n\n### Terms\n- **Hash**: a fixed-size value calculated from data and used to help detect changes.\n\n### Remember\nIntegrity evidence alone is not proof of identity.