Man-In-The-Middle Extender Defense In Data Communications

A method of determining whether a received message at a communications device is from a legitimate second device may include building a message intended for a legitimate second device, generating a time delay using a secret key known to the device and the legitimate second device, sending the built message to the legitimate second device, starting a timer at the time of sending the built message, receiving a response to the sent message, determining a response time of the received response based on a time value of the timer, determining an acceptable receive window of time based on the generated time delay, determining whether the determined response time is within the determined acceptable receive window of time, and when the determined response time is within the determined acceptable receive window of time, recognizing the received response as a legitimate message from the legitimate second device.