Overview#Entity Authentication is the Authentication of an entity
Some Definitions#Entity Authentication is defined in the ISO Security Architecture as: 'the corroboration that an entity is the one claimed'
Handbook of Applied Cryptography has definition is given as: "Entity Authentication is the process whereby one party is assured (through acquisition of corroborative evidence) of the identity of a second party involved in a protocol, and that the second has actually participated (i.e., is active at, or immediately prior to, the time the evidence is acquired)."
Entity Authentication contrasted to Message Authentication #A major difference between entity authentication and message authentication (as provided by digital signatures or MACs) is that message authentication itself provides no timeliness guarantees with respect to when a message was created, whereas entity authentication involves corroboration of a claimant’s identity through actual communications with an associated verifier during execution of the protocol itself (i.e., in real-time, while the verifying entity awaits).
Conversely, entity authentication typically involves no meaningful message other than the claim of being a particular entity, whereas Message Authentication does.