Add NUS-encrypted FIRM support (thanks to CakesFW)

source/crypto.c

@@ -23,6 +23,7 @@
 /*
 *   Crypto libs from http://github.com/b1l1s/ctr
 *   ARM9Loader code originally adapted from https://github.com/Reisyukaku/ReiNand/blob/228c378255ba693133dec6f3368e14d386f2cde7/source/crypto.c#L233
+*   decryptNusFirm code adapted from https://github.com/mid-kid/CakesForeveryWan/blob/master/source/firm.c
 */
 
 #include "crypto.h"
@@ -367,23 +368,42 @@ void setRSAMod0DerivedKeys(void)
     }
 }
 
-//Decrypt a FIRM ExeFS
 void decryptExeFs(u8 *inbuf)
 {
     u8 *exeFsOffset = inbuf + *(u32 *)(inbuf + 0x1A0) * 0x200;
     u32 exeFsSize = *(u32 *)(inbuf + 0x1A4) * 0x200;
-    u8 ncchCTR[0x10] = {0};
+    u8 __attribute__((aligned(4))) ncchCTR[0x10] = {0};
 
     for(u32 i = 0; i < 8; i++)
         ncchCTR[7 - i] = *(inbuf + 0x108 + i);
     ncchCTR[8] = 2;
 
     aes_setkey(0x2C, inbuf, AES_KEYY, AES_INPUT_BE | AES_INPUT_NORMAL);
-    aes_setiv(ncchCTR, AES_INPUT_BE | AES_INPUT_NORMAL);
     aes_use_keyslot(0x2C);
     aes(inbuf - 0x200, exeFsOffset, exeFsSize / AES_BLOCK_SIZE, ncchCTR, AES_CTR_MODE, AES_INPUT_BE | AES_INPUT_NORMAL);
 }
 
+void decryptNusFirm(u8 *inbuf, u8 *outbuf, u32 ncchSize)
+{
+    const u8 keyY0x3D[0x10] = {0x0C, 0x76, 0x72, 0x30, 0xF0, 0x99, 0x8F, 0x1C, 0x46, 0x82, 0x82, 0x02, 0xFA, 0xAC, 0xBE, 0x4C};
+    u8 __attribute__((aligned(4))) cetkIv[0x10] = {0};
+    u8 __attribute__((aligned(4))) titleKey[0x10];
+    memcpy(titleKey, inbuf + 0x1BF, 0x10);
+    memcpy(cetkIv, inbuf + 0x1DC, 8);
+
+    aes_setkey(0x3D, keyY0x3D, AES_KEYY, AES_INPUT_BE | AES_INPUT_NORMAL);
+    aes_use_keyslot(0x3D);
+    aes(titleKey, titleKey, 1, cetkIv, AES_CBC_DECRYPT_MODE, AES_INPUT_BE | AES_INPUT_NORMAL);
+
+    u8 ncchIv[0x10] = {0};
+
+    aes_setkey(0x16, titleKey, AES_KEYNORMAL, AES_INPUT_BE | AES_INPUT_NORMAL);
+    aes_use_keyslot(0x16);
+    aes(outbuf, outbuf, ncchSize / AES_BLOCK_SIZE, ncchIv, AES_CBC_DECRYPT_MODE, AES_INPUT_BE | AES_INPUT_NORMAL);
+
+    decryptExeFs(outbuf);
+}
+
 //ARM9Loader replacement
 void arm9Loader(u8 *arm9Section)
 {
@@ -440,7 +460,6 @@ void arm9Loader(u8 *arm9Section)
     }
 
     aes_setkey(arm9BinSlot, keyY, AES_KEYY, AES_INPUT_BE | AES_INPUT_NORMAL);
-    aes_setiv(arm9BinCTR, AES_INPUT_BE | AES_INPUT_NORMAL);
     aes_use_keyslot(arm9BinSlot);
 
     //Decrypt arm9bin

source/crypto.h

@@ -23,6 +23,7 @@
 /*
 *   Crypto libs from http://github.com/b1l1s/ctr
 *   ARM9Loader code originally adapted from https://github.com/Reisyukaku/ReiNand/blob/228c378255ba693133dec6f3368e14d386f2cde7/source/crypto.c#L233
+*   decryptNusFirm code adapted from https://github.com/mid-kid/CakesForeveryWan/blob/master/source/firm.c
 */
 
 #pragma once
@@ -108,5 +109,6 @@ void ctrNandInit(void);
 u32 ctrNandRead(u32 sector, u32 sectorCount, u8 *outbuf);
 void setRSAMod0DerivedKeys(void);
 void decryptExeFs(u8 *inbuf);
+void decryptNusFirm(u8 *inbuf, u8 *outbuf, u32 ncchSize);
 void arm9Loader(u8 *arm9Section);
 void computePinHash(u8 *out, u8 *in);

source/firm.c

@@ -271,11 +271,17 @@ static inline u32 loadFirm(FirmwareType *firmType, FirmwareSource firmSource)
 {
     section = firm->section;
 
-    const char *firmwareFiles[4] = {
+    const char *firmwareFiles[] = {
         "/luma/firmware.bin",
         "/luma/firmware_twl.bin",
         "/luma/firmware_agb.bin",
         "/luma/firmware_safe.bin"
+    },
+               *cetkFiles[] = {
+        "/luma/cetk",
+        "/luma/cetk_twl",
+        "/luma/cetk_agb",
+        "/luma/cetk_safe"
     };
 
     //Load FIRM from CTRNAND
@@ -300,11 +306,26 @@ static inline u32 loadFirm(FirmwareType *firmType, FirmwareSource firmSource)
         else if(firmVersion < 0x25) loadFromSd = true;
     }
 
-    //Check that the SD FIRM is right for the console from the ARM9 section address
+    u32 firmSize = fileRead(firm, *firmType == NATIVE_FIRM1X2X ? firmwareFiles[0] : firmwareFiles[(u32)*firmType], 0x400000);
-    if(fileRead(firm, *firmType == NATIVE_FIRM1X2X ? firmwareFiles[0] : firmwareFiles[(u32)*firmType], 0x400000) &&
+
-       ((section[3].offset ? section[3].address : section[2].address) == (isN3DS ? (u8 *)0x8006000 : (u8 *)0x8006800)))
+    if(firmSize > 0)
+    {
+        if(memcmp(firm, "FIRM", 4) != 0)
+        {
+            u8 cetk[0xA50];
+
+            if(fileRead(cetk, *firmType == NATIVE_FIRM1X2X ? cetkFiles[0] : cetkFiles[(u32)*firmType], sizeof(cetk)))
+                decryptNusFirm(cetk, (u8 *)firm, firmSize);
+        }
+
+        //Check that the SD FIRM is right for the console from the ARM9 section address
+        if((section[3].offset ? section[3].address : section[2].address) != (isN3DS ? (u8 *)0x8006000 : (u8 *)0x8006800))
+            error("The firmware.bin in /luma is not valid for your\nconsole, or corrupted");
+
         firmVersion = 0xFFFFFFFF;
-    else
+    }
+
+    if(firmVersion != 0xFFFFFFFF)
     {
         if(loadFromSd) error("An old unsupported FIRM has been detected.\nCopy a valid firmware.bin in /luma to boot");
         decryptExeFs((u8 *)firm);
@@ -336,10 +357,22 @@ static inline u32 loadFirm(FirmwareType *firmType, FirmwareSource firmSource)
         //We can't boot a 3.x/4.x NATIVE_FIRM, load one from SD
         else if(firmVersion < 0x25)
         {
-            if(!fileRead(firm, "/luma/firmware.bin", 0x400000) || section[2].address != (u8 *)0x8006800)
+            u32 firmSize = fileRead(firm, "/luma/firmware.bin", 0x400000);
-                error("An old unsupported FIRM has been detected.\nCopy a valid firmware.bin in /luma to boot");
 
-            firmVersion = 0xFFFFFFFF;
+            if(firmSize > 0)
+            {
+                if(memcmp(firm, "FIRM", 4) != 0)
+                {
+                    u8 cetk[0xA50];
+
+                    if(fileRead(cetk, "/luma/cetk", sizeof(cetk)))
+                        decryptNusFirm(cetk, (u8 *)firm, firmSize);
+                }
+
+                if(section[2].address != (u8 *)0x8006800) firmVersion = 0xFFFFFFFF;
+            }
+
+            if(firmVersion != 0xFFFFFFFF) error("An old unsupported FIRM has been detected.\nCopy a valid firmware.bin in /luma to boot");
         }
     }
 

source/fs.c

@@ -149,7 +149,7 @@ void loadPayload(u32 pressed)
 
 u32 firmRead(void *dest, u32 firmType)
 {
-    const char *firmFolders[4][2] = {{ "00000002", "20000002" },
+    const char *firmFolders[][2] = {{ "00000002", "20000002" },
                                     { "00000102", "20000102" },
                                     { "00000202", "20000202" },
                                     { "00000003", "20000003" }};