A method for activating at least one function of a control device of a motor vehicle, which includes the steps: a) generating a random value in the control device; b) calculating a reference value from the random value by the control device; c) transmitting the random value to a remote control unit and from the remote control unit to a server; d) verifying the authorization of the remote control unit transmitting the random value by the server and if an authorization of the remote control unit is provided: e) generating a response value from the random value by the server; f) transmitting the response value to the remote control unit and from the remote control unit to the control device; and g) comparing the response value with the reference value and, if the response value matches the reference value, activating the at least one function of the control device.