diff --git a/parentool/Makefile b/parentool/Makefile
new file mode 100644
index 0000000..a340ac7
--- /dev/null
+++ b/parentool/Makefile
@@ -0,0 +1,13 @@
+OBJS = main.o
+LIBS = 
+CXXFLAGS = -I. 
+CFLAGS = -Wall -I.
+OUTPUT = parentool
+CC = gcc
+
+main: $(OBJS) 
+	g++ -o $(OUTPUT) $(LIBS) $(OBJS) 
+
+
+clean:
+	rm -rf $(OUTPUT) $(OBJS)
diff --git a/parentool/main.c b/parentool/main.c
new file mode 100644
index 0000000..b22198d
--- /dev/null
+++ b/parentool/main.c
@@ -0,0 +1,82 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdint.h>
+
+unsigned int calculate_master_key(unsigned char* generator)
+{
+	uint32_t table[0x100];
+	uint32_t data;
+	uint32_t i, j;
+	uint32_t y;
+	uint8_t x;
+	uint64_t yll;
+	uint32_t yhi;
+
+	for(i=0; i<0x100; i++)
+	{
+		data = i;
+		for(j=0; j<4; j++)
+		{
+			if (data & 1)
+				data = 0xEDBA6320 ^ (data>>1);
+			else
+				data = data>>1;
+
+			if (data & 1)
+				data = 0xEDBA6320 ^ (data>>1);
+			else
+				data = data>>1;
+		}
+
+		table[i] = data;
+	}
+
+	y = 0xFFFFFFFF;
+	x = generator[0];
+	for(i=0; i<4; i++)
+	{
+		x ^= y;
+		y = table[x] ^ (y>>8);
+		x = generator[1+i*2] ^ y;
+		y = table[x] ^ (y>>8);
+		x = generator[2+i*2];
+	}
+
+	y ^= 0xAAAA;
+	y += 0x1657;
+
+	yll = y;
+	yll = (yll+1) * 0xA7C5AC47ULL;
+	yhi = (yll>>48);
+	yhi *= 0xFFFFF3CB;
+	y += (yhi<<5);
+
+	return y;
+}
+
+int main(int argc, const char* argv[])
+{
+	unsigned char generator[9] = {0};
+	unsigned int servicecode, month, day, masterkey;
+
+	if (argc != 4)
+	{
+		printf("usage: <servicecode> <month> <day>\n");
+		exit(1);
+	}
+
+	servicecode = strtoul(argv[1], 0, 10);
+	month = strtoul(argv[2], 0, 10);
+	day = strtoul(argv[3], 0, 10);
+	
+	servicecode %= 10000;
+	month %= 100;
+	day %= 100;
+	sprintf((char*)generator, "%02d%02d%04d", month, day, servicecode);
+
+	masterkey = calculate_master_key(generator);
+
+	printf("Master key is %05d\n", masterkey);
+	return 0;
+}