Philips Sonicare NFC Password generation

@@ -0,0 +1,36 @@
+#include <stdio.h>
+#include <stdint.h>
+// Philips Sonicare NFC Head Password calculation by @atc1441
+uint16_t CRC16(uint16_t crc, uint8_t *buffer, int len) // Default CRC16 Algo
+{
+  while(len--)
+  {
+    crc ^= *buffer++ << 8;
+    int bits = 0;
+    do
+    {
+      if ( (crc & 0x8000) != 0 )
+        crc = (2 * crc) ^ 0x1021;
+      else
+        crc *= 2;
+    }
+    while ( ++bits < 8 );
+  }
+  return crc;
+}
+
+uint8_t nfctag_uid[] = {0x04,0xEC,0xFC,0xA2,0x94,0x10,0x90}; // NTAG UID
+uint8_t nfc_second[] = "221214 12K"; // Head MFG String, printed on Head and at memory location 0x23
+
+int main()
+{
+    uint32_t crc_calc = CRC16(0x49A3, nfctag_uid, 7); // Calculate the NTAG UID CRC
+    
+    crc_calc = crc_calc | (CRC16(crc_calc, nfc_second, 10) << 16); // Calculate the MFG CRC
+    
+    crc_calc = (crc_calc >> 8) & 0x00FF00FF | (crc_calc << 8) & 0xFF00FF00; // Rotate the uin16_t bytes
+    
+    printf("by @ATC1441 NFC CRC : 0x%08X expected: 0x61F0A50F\r\n", crc_calc);// Print out the calucated password
+
+    return 0;
+}