diff --git a/makerom/aes_keygen.c b/makerom/aes_keygen.c
new file mode 100644
index 0000000..e5a35d6
--- /dev/null
+++ b/makerom/aes_keygen.c
@@ -0,0 +1,124 @@
+#include "aes_keygen.h"
+
+// 128bit wrap-around math
+int32_t wrap_index(int32_t i)
+{
+	return i < 0 ? ((i % 16) + 16) % 16 : (i > 15 ? i % 16 : i);
+}
+
+void n128_rrot(const uint8_t *in, uint32_t rot, uint8_t *out)
+{
+	uint32_t bit_shift, byte_shift;
+
+	rot = rot % 128;
+	byte_shift = rot / 8;
+	bit_shift = rot % 8;
+
+	for (int32_t i = 0; i < 16; i++) {
+		out[i] = (in[wrap_index(i - byte_shift)] >> bit_shift) | (in[wrap_index(i - byte_shift - 1)] << (8 - bit_shift));
+	}
+
+}
+
+void n128_lrot(const uint8_t *in, uint32_t rot, uint8_t *out)
+{
+	uint32_t bit_shift, byte_shift;
+
+	rot = rot % 128;
+	byte_shift = rot / 8;
+	bit_shift = rot % 8;
+
+	for (int32_t i = 0; i < 16; i++) {
+		out[i] = (in[wrap_index(i + byte_shift)] << bit_shift) | (in[wrap_index(i + byte_shift + 1)] >> (8 - bit_shift));
+	}
+}
+
+/* out = a + b
+*/
+void n128_add(const uint8_t *a, const uint8_t *b, uint8_t *out)
+{
+	uint8_t carry = 0;
+	uint32_t sum = 0;
+
+	for (int i = 15; i >= 0; i--) {
+		sum = a[i] + b[i] + carry;
+		carry = sum >> 8;
+		out[i] = sum & 0xff;
+	}
+
+	while (carry != 0) {
+		for (int i = 15; i >= 0; i--) {
+			sum = out[i] + carry;
+			carry = sum >> 8;
+			out[i] = sum & 0xff;
+		}
+	}
+}
+
+/* out = a - b
+*/
+void n128_sub(const uint8_t *a, const uint8_t *b, uint8_t *out)
+{
+	uint8_t carry = 0;
+	uint32_t sum = 0;
+
+	for (int i = 15; i >= 0; i--) {
+		sum = a[i] - (b[i] + carry);
+
+		// check to see if anything was borrowed from next byte
+		if (a[i] < (b[i] + carry)) {
+			sum += 0x100;
+			carry = 1;
+		}
+		else {
+			carry = 0;
+		}
+
+		// set value
+		out[i] = sum & 0xff;
+	}
+
+
+	while (carry != 0) {
+		for (int i = 15; i >= 0; i--) {
+			sum = out[i] - carry;
+
+			// check to see if anything was borrowed from next byte
+			if (out[i] < carry) {
+				sum += 0x100;
+				carry = 1;
+			}
+			else {
+				carry = 0;
+			}
+
+			out[i] = sum & 0xff;
+		}
+	}
+
+}
+
+void n128_xor(const uint8_t *a, const uint8_t *b, uint8_t *out)
+{
+	for (int i = 0; i < 16; i++) {
+		out[i] = a[i] ^ b[i];
+	}
+}
+
+// keygen algorithm
+void n_aes_keygen(const uint8_t *x, uint8_t x_shift, const uint8_t *y, uint8_t y_shift, const uint8_t *keygen_constant, uint8_t *key)
+{
+	// overall algo:
+	// key = ((x >>> x_shift) ^ (y >>> y_shift)) + keygen_constant
+	uint8_t x_rot[16], y_rot[16], key_xy[16];
+
+	// Rotate x and y
+	n128_rrot(x, x_shift, x_rot);
+	n128_rrot(y, y_shift, y_rot);
+
+	// XOR rotated x and y
+	n128_xor(x_rot, y_rot, key_xy);
+
+	// Add secret
+	n128_add(key_xy, keygen_constant, key);
+}
\ No newline at end of file
diff --git a/makerom/aes_keygen.h b/makerom/aes_keygen.h
new file mode 100644
index 0000000..0314744
--- /dev/null
+++ b/makerom/aes_keygen.h
@@ -0,0 +1,12 @@
+#pragma once
+#include <stdint.h>
+
+/*
+	AES Key generator for the Nintendo (Handheld) Consoles
+
+	BYO keygen constants, and input >>> parameters
+
+	key = ((x >>> x_shift) ^ (y >>> y_shift)) + keygen_constant
+*/
+
+void n_aes_keygen(const uint8_t *x, uint8_t x_shift, const uint8_t *y, uint8_t y_shift, const uint8_t *keygen_constant, uint8_t *key);
diff --git a/makerom/keyset.c b/makerom/keyset.c
index cdb32a6..d468471 100644
--- a/makerom/keyset.c
+++ b/makerom/keyset.c
@@ -1,4 +1,5 @@
 #include "lib.h"
+#include "aes_keygen.h"
 
 // KeyData
 #include "pki/test.h" // Test PKI
@@ -49,16 +50,10 @@ void PrintBadKeySize(char *path, u32 size)
 
 u8* AesKeyScrambler(u8 *key, const u8 *keyX, const u8 *keyY)
 {
-	// Process keyX/keyY to get raw normal key
-	for(int i = 0; i < 16; i++)
-		key[i] = keyX[i] ^ ((keyY[i] >> 2) | ((keyY[i < 15 ? i+1 : 0] & 3) << 6)); // keyX[i] ^
-
-	const u8 SCRAMBLE_SECRET[16] = {0x51, 0xD7, 0x5D, 0xBE, 0xFD, 0x07, 0x57, 0x6A, 0x1C, 0xFC, 0x2A, 0xF0, 0x94, 0x4B, 0xD5, 0x6C};
-
-	// Apply Secret to get final normal key
-	for(int i = 0; i < 16; i++)
-		key[i] = key[i] ^ SCRAMBLE_SECRET[i];
-
+	static const uint8_t CTR_KEYGEN_CONST[16] = { 0xEE, 0x2E, 0xA9, 0x3B, 0x45, 0x0F, 0xFC, 0xF4, 0xD5, 0x62, 0xFF, 0x02, 0x04, 0x01, 0x22, 0xC8 };
+	static const uint8_t CTR_KEYX_SHIFT = 39;
+	static const uint8_t CTR_KEYY_SHIFT = 41;
+	n_aes_keygen(keyX, CTR_KEYX_SHIFT, keyY, CTR_KEYY_SHIFT, CTR_KEYGEN_CONST, key);
 	return key;
 }
 
diff --git a/makerom/makerom.vcxproj b/makerom/makerom.vcxproj
index 7d44201..dbdfd0a 100644
--- a/makerom/makerom.vcxproj
+++ b/makerom/makerom.vcxproj
@@ -91,6 +91,7 @@
   </ItemGroup>
   <ItemGroup>
     <ClInclude Include="accessdesc.h" />
+    <ClInclude Include="aes_keygen.h" />
     <ClInclude Include="blz.h" />
     <ClInclude Include="cardinfo.h" />
     <ClInclude Include="certs.h" />
@@ -194,6 +195,7 @@
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="accessdesc.c" />
+    <ClCompile Include="aes_keygen.c" />
     <ClCompile Include="blz.c" />
     <ClCompile Include="cardinfo.c" />
     <ClCompile Include="certs.c" />
diff --git a/makerom/makerom.vcxproj.filters b/makerom/makerom.vcxproj.filters
index 472d9e1..992fd34 100644
--- a/makerom/makerom.vcxproj.filters
+++ b/makerom/makerom.vcxproj.filters
@@ -339,6 +339,9 @@
     <ClInclude Include="desc\desc.h">
       <Filter>Resource Files\DESC</Filter>
     </ClInclude>
+    <ClInclude Include="aes_keygen.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="accessdesc.c">
@@ -479,6 +482,9 @@
     <ClCompile Include="oschar.c">
       <Filter>Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="aes_keygen.c">
+      <Filter>Source Files</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <None Include="Makefile">