A secure communications and location authorization system using a power line or a potion thereof as a side-channel that mitigates man-in-the-middle attacks on communications networks and devices connected to those networks. The system includes a power grid server associated with a substation, or curb-side distribution structure such as a transformer, an electric meter associated with a structure having electric service and able to communicate with the power grid server, a human authorization detector input device connected to the electric meter and the power grid server. The human authorization detector is able to receive an input from a user physically located at the structure and capable of communicating with the power grid server via the electric meter. The user's physical input into the device causing a request to be sent to the power grid server that then generates a location certificate for the user. Without the location certificate, access to the communications network and devices connected to those networks can be denied.