A security system comprising an implant, a control device, and a machine, wherein the machine has a control device which is designed to - permit operation of the machine only in the event that a unique identifier is received, and - set an operating mode of the machine depending on a suitability index which is received, the suitability index describing the suitability of an implant wearer to operate a machine, wherein the implant is designed to detect physiological data on an implant wearer, and wherein the control device has - a first interface, which is designed for wireless communication with the implant, - a second interface, which is designed for wireless communication with the control unit of the machine, - and a memory for a unique identifier, wherein the machine is a vehicle and the control unit is part of a vehicle electronics system, and either (a.1) wherein the implant is designed to generate a suitability index from detected physiological data and transmit the suitability index to the control device, and (a.2) wherein the first interface is designed to receive the suitability index, and wherein the second interface is designed to transfer the suitability index together with the unique identifier to the control unit of the machine, or (b.1) wherein the implant is designed to transmit the physiological data itself to the control device, and (b.2) wherein the first interface is designed to receive the physiological parameters from the implant, and wherein the second interface is designed to transmit the suitability index together with the unique identifier to the control unit of the machine, wherein the control device has a classification unit which is designed to receive the physiological data, assign received physiological data to one of several predefined suitability classes, and generate an index which characterizes the particular assigned suitability class, and to provide the index, as a suitability index, to the second interface. - permit operation of the machine only in the event that a unique identifier is received, and - set an operating mode of the machine depending on a suitability index which is received, the suitability index describing the suitability of an implant wearer to operate a machine, - a first interface, which is designed for wireless communication with the implant, - a second interface, which is designed for wireless communication with the control unit of the machine, - and a memory for a unique identifier, (a.1) wherein the implant is designed to generate a suitability index from detected physiological data and transmit the suitability index to the control device, and (a.2) wherein the first interface is designed to receive the suitability index, and wherein the second interface is designed to transfer the suitability index together with the unique identifier to the control unit of the machine, (b.1) wherein the implant is designed to transmit the physiological data itself to the control device, and (b.2) wherein the first interface is designed to receive the physiological parameters from the implant, and wherein the second interface is designed to transmit the suitability index together with the unique identifier to the control unit of the machine, wherein the control device has a classification unit which is designed to receive the physiological data, assign received physiological data to one of several predefined suitability classes, and generate an index which characterizes the particular assigned suitability class, and to provide the index, as a suitability index, to the second interface.