An ID token comprising a sensor (70, 72), a communication interface, and a first microcontroller, wherein the ID token comprises a protected second microcontroller having at least one microcontroller communication interface, which is arranged in a holder of the ID token, wherein the microcontroller communication interface provides a data input and a data output, • wherein the sensor (70, 72) is configured to sense measurement data, • wherein the first microcontroller, for data exchange with the microcontroller communication interface of the protected second microcontroller, is connected to the sensor (70, 72) and to the communication interface of the ID token, and wherein the first microcontroller is configured to exchange data with a reading device via the communication interface of the ID token, • wherein the protected second microcontroller comprises a first and a second application (56, 58), • wherein the first application is configured to compare the measurement data of the sensor (70, 72) with comparison data stored in a memory of the second microcontroller and to forward the comparison result to the second application, • wherein the second application is configured to establish a connection to the reading device and to output specified data by a read command of the reading device, • wherein the first microcontroller is configured as a proxy for switching between the sensing of the measurement data by the sensor (70, 72) and forwarding of the sensed measurement data from the sensor (70, 72) to the first application of the protected second microcontroller by means of the microcontroller communication interface thereof on the one hand and forwarding of notifications for establishing a connection between the second application and the reading device and/or forwarding of APDUs by means of the connection between the second application and the reading device on the other hand, wherein the first microcontroller is configured: • to receive and temporarily store a first request of the reading device to establish the connection between the second application and the reading device, • upon receipt of the first request, to send a second request to sense the measurement data to the sensor (70, 72) as a precautionary measure, • in response to the second request, to receive the sensed measurement data from the sensor (70, 72) and to forward said data to the first application, so that the sensed measurement data are available to the second microcontroller as necessary, • to forward the temporarily stored first request to the second application upon forwarding of the sensed measurement data. • wherein the sensor (70, 72) is configured to sense measurement data, • wherein the first microcontroller, for data exchange with the microcontroller communication interface of the protected second microcontroller, is connected to the sensor (70, 72) and to the communication interface of the ID token, and wherein the first microcontroller is configured to exchange data with a reading device via the communication interface of the ID token, • wherein the protected second microcontroller comprises a first and a second application (56, 58), • wherein the first application is configured to compare the measurement data of the sensor (70, 72) with comparison data stored in a memory of the second microcontroller and to forward the comparison result to the second application, • wherein the second application is configured to establish a connection to the reading device and to output specified data by a read command of the reading device, • wherein the first microcontroller is configured as a proxy for switching between the sensing of the measurement data by the sensor (70, 72) and forwarding of the sensed measurement data from the sensor (70, 72) to the first application of the protected second microcontroller by means of the microcontroller communication interface thereof on the one hand and forwarding of notifications for establishing a connection between the second application and the reading device and/or forwarding of APDUs by means of the connection between the second application and the reading device on the other hand, • to receive and temporarily store a first request of the reading device to establish the connection between the second application and the reading device, • upon receipt of the first request, to send a second request to sense the measurement data to the sensor (70, 72) as a precautionary measure, • in response to the second request, to receive the sensed measurement data from the sensor (70, 72) and to forward said data to the first application, so that the sensed measurement data are available to the second microcontroller as necessary, • to forward the temporarily stored first request to the second application upon forwarding of the sensed measurement data.