From cd14ba916dc79425e822f90226fb22eecf6464cf Mon Sep 17 00:00:00 2001
From: Louis Burda <quent.burda@gmail.com>
Date: Mon, 12 Mar 2018 17:27:39 +0100
Subject: [PATCH] Arduino Implementation

---
 NfcKeyC.ino | 121 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 121 insertions(+)
 create mode 100644 NfcKeyC.ino

diff --git a/NfcKeyC.ino b/NfcKeyC.ino
new file mode 100644
index 0000000..2a0e0ea
--- /dev/null
+++ b/NfcKeyC.ino
@@ -0,0 +1,121 @@
+#include <SPI.h>
+#include <MFRC522.h>
+
+#include <stdio.h>
+#include <inttypes.h>
+#include <string.h>
+
+#ifndef ROTL
+# define ROTL(x,n) (((uintmax_t)(x) << (n)) | ((uintmax_t)(x) >> ((sizeof(x) * 8) - (n))))
+#endif
+
+constexpr uint8_t RST_PIN = 9;
+constexpr uint8_t SS_PIN = 10;
+
+MFRC522 mfrc522(SS_PIN, RST_PIN);
+
+uint32_t c[] = {
+	0x6D835AFC, 0x7D15CD97, 0x0942B409, 0x32F9C923, 0xA811FB02, 0x64F121E8,
+	0xD1CC8B4E, 0xE8873E6F, 0x61399BBB, 0xF1B91926, 0xAC661520, 0xA21A31C9,
+	0xD424808D, 0xFE118E07, 0xD18E728D, 0xABAC9E17, 0x18066433, 0x00E18E79,
+	0x65A77305, 0x5AE9E297, 0x11FC628C, 0x7BB3431F, 0x942A8308, 0xB2F8FD20,
+	0x5728B869, 0x30726D5A
+};
+
+void setup() {
+	Serial.begin(115200);
+	while (!Serial);
+	SPI.begin();
+	mfrc522.PCD_Init();
+
+	pinMode(2, OUTPUT);
+	digitalWrite(2, HIGH);
+
+	Serial.println("Hold the cartridge tag over the reader..");
+	while (!mfrc522.PICC_IsNewCardPresent() || !mfrc522.PICC_ReadCardSerial());
+	uint32_t k = getkey(mfrc522.uid.uidByte);
+	uint16_t p = getpack(mfrc522.uid.uidByte);
+	Serial.print("UID:"); printHex(mfrc522.uid.uidByte, 7);
+	Serial.print("KEY:"); Serial.println(k, HEX);
+	Serial.print("PACK:"); Serial.println(p, HEX);
+}
+
+void loop() {}
+
+void printHex(uint8_t array[], unsigned int len) {
+	char buffer[3];
+	buffer[2] = NULL;
+	for (int j = 0; j < len; j++) {
+		sprintf(&buffer[0], "%02X", array[j]);
+		Serial.print(buffer);
+	} Serial.println();
+}
+
+void transform(uint8_t* ru)
+{
+	//Transform
+	uint8_t i;
+	uint8_t p = 0;
+	uint32_t v1 = (((uint32_t)ru[3] << 24) | ((uint32_t)ru[2] << 16) | ((uint32_t)ru[1] << 8) | (uint32_t)ru[0]) + c[p++];
+	uint32_t v2 = (((uint32_t)ru[7] << 24) | ((uint32_t)ru[6] << 16) | ((uint32_t)ru[5] << 8) | (uint32_t)ru[4]) + c[p++];
+
+	for (i = 0; i < 12; i += 2)
+	{
+		uint32_t t1 = ROTL(v1 ^ v2, v2 & 0x1F) + c[p++];
+		uint32_t t2 = ROTL(v2 ^ t1, t1 & 0x1F) + c[p++];
+		v1 = ROTL(t1 ^ t2, t2 & 0x1F) + c[p++];
+		v2 = ROTL(t2 ^ v1, v1 & 0x1F) + c[p++];
+	}
+
+	//Re-use ru
+	ru[0] = v1 & 0xFF;
+	ru[1] = (v1 >> 8) & 0xFF;
+	ru[2] = (v1 >> 16) & 0xFF;
+	ru[3] = (v1 >> 24) & 0xFF;
+	ru[4] = v2 & 0xFF;
+	ru[5] = (v2 >> 8) & 0xFF;
+	ru[6] = (v2 >> 16) & 0xFF;
+	ru[7] = (v2 >> 24) & 0xFF;
+}
+
+uint32_t getkey(uint8_t* uid)
+{
+	int i;
+	//Rotate
+	uint8_t r = (uid[1] + uid[3] + uid[5]) & 7; //Rotation offset
+	uint8_t ru[8] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }; //Rotated UID
+	for (i = 0; i < 7; i++)
+		ru[(i + r) & 7] = uid[i];
+
+	//Transform
+	transform(ru);
+
+	//Calc key
+	uint32_t k = 0; //Key as int
+	r = (ru[0] + ru[2] + ru[4] + ru[6]) & 3; //Offset
+	for (i = 4; i >= 0; i--) 
+		k = ru[i + r] + (k << 8);
+
+	return k;
+}
+
+uint16_t getpack(uint8_t* uid)
+{
+	int i;
+	//Rotate
+	uint8_t r = (uid[2] + uid[5]) & 7; //Rotation offset
+	uint8_t ru[8] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }; //Rotated UID
+	for (i = 0; i < 7; i++)
+		ru[(i + r) & 7] = uid[i];
+
+	//Transform
+	transform(ru);
+
+	//Calc pack
+	uint32_t p = 0;
+	for (i = 0; i < 8; i++)
+		p += ru[i] * 13;
+	
+	p = (p ^ 0x5555) & 0xFFFF;
+	return (p & 0xFF00) >> 8 | (p & 0x00FF) << 8;
+}
\ No newline at end of file