Embodiments are disclosed for limiting an attack surface of a server application by enforcing integrity of a message transmitted to the server application. An example method includes receiving, by communications circuitry of a receiving system hosting the server application, a message including specific message content and a token. The example method further includes determining, by authentication circuitry of the receiving system and using the specific message content, whether the token comprises a valid message integrity secure token. If the token comprises a valid message integrity secure token, the example method further includes performing, by response circuitry of the receiving system, an operation in response to the message. If not, the method may include generating, by the authentication circuitry of the receiving system, an error message. Corresponding apparatuses and computer program products are also provided.