diff --git a/arduino_nano/main.c b/arduino_nano/main.c
index 280834f..19a471c 100644
--- a/arduino_nano/main.c
+++ b/arduino_nano/main.c
@@ -30,6 +30,7 @@
 #include <avr/wdt.h> // Watchdog timer handling
 #include <avr/pgmspace.h> // Program Space Utilities
 #include <avr/sleep.h> // Power Management and Sleep Modes
+#include <util/crc16.h> // CRC Computations
 
 #include "main.h" // main definitions
 #include "usart.h" // basic USART functions
@@ -91,8 +92,7 @@ void io_init(void)
 int main(void)
 {
 	io_init(); // initialize IOs
-	uint8_t nrf24_payload[1+4*4] = {0}; // measurement values to be sent: ID byte + encrypted 4x4 float values (voltage, current, power, energy)
-	nrf24_payload[0] = conf.id; // set ID
+	uint8_t nrf24_payload[1+4*4+1] = {0}; // measurement values to be sent: ID byte + encrypted 4x4 float values (voltage, current, power, energy) + 1 CRC8 Mixim/Dallas/iButton/1Wire of the plain text (to know if the key/IV is correct)
 	
 	//printf(PSTR("welcome to the spar counter power meter monitor\n"));
 	
@@ -110,6 +110,15 @@ int main(void)
 	/* start encryption */
 	aes128_ctx_t ctx; // the context where the round keys are stored
 	aes128_init(conf.key, &ctx); // generating the round keys from the 128 bit key
+	// set data to invalid
+	memset(&nrf24_payload[1],0xff,sizeof(conf.iv));
+	// set ID
+	nrf24_payload[0] = conf.id;
+	// calculate CRC over values
+	nrf24_payload[17] = 0;
+	for (uint8_t i = 0; i < sizeof(conf.iv); i++) {
+		nrf24_payload[17] = _crc_ibutton_update(nrf24_payload[17], nrf24_payload[1+i]);
+	}
 	// XOR data with IV for AES CBC mode
 	for (uint8_t i=0; i<sizeof(nrf24_payload)-1 && i<sizeof(conf.iv); i++) {
 		nrf24_payload[i+1] ^= conf.iv[i];
@@ -216,6 +225,13 @@ int main(void)
 			memcpy(&nrf24_payload[1+4],&current,4); // populate current
 			memcpy(&nrf24_payload[1+8],&power,4); // populate power
 			memcpy(&nrf24_payload[1+12],&energy,4); // populate energy
+			// set ID
+			nrf24_payload[0] = conf.id;
+			// calculate CRC over values
+			nrf24_payload[17] = 0;
+			for (uint8_t i = 0; i < sizeof(conf.iv); i++) {
+			nrf24_payload[17] = _crc_ibutton_update(nrf24_payload[17], nrf24_payload[1+i]);
+			}
 			// XOR data with last data for AES CBC mode
 			for (uint8_t i=0; i<sizeof(nrf24_payload)-1 && i<sizeof(conf.iv); i++) {
 				nrf24_payload[i+1] ^= conf.iv[i];