Add support for launching >= 6.x/7.x emuNANDs properly when the sysNAND is on a lower firmware version

To launch 3.x - 4.x emuNANDs, you'll need to use an external firmware file (10.x or so should do the trick)

source/crypto.c

@@ -347,6 +347,16 @@ u32 ctrNandRead(u32 sector, u32 sectorCount, u8 *outbuf)
     return result;
 }
 
+//Sets the 7.x NCCH KeyX and the 6.x gamecard save data KeyY
+void setRSAMod0DerivedKeys(void)
+{
+    const u8 keyX0x25[0x10] = {0xCE, 0xE7, 0xD8, 0xAB, 0x30, 0xC0, 0x0D, 0xAE, 0x85, 0x0E, 0xF5, 0xE3, 0x82, 0xAC, 0x5A, 0xF3};
+    const u8 keyY0x2F[0x10] = {0xC3, 0x69, 0xBA, 0xA2, 0x1E, 0x18, 0x8A, 0x88, 0xA9, 0xAA, 0x94, 0xE5, 0x50, 0x6A, 0x9F, 0x16};
+
+    aes_setkey(0x25, keyX0x25, AES_KEYX, AES_INPUT_BE | AES_INPUT_NORMAL);
+    aes_setkey(0x2F, keyY0x2F, AES_KEYY, AES_INPUT_BE | AES_INPUT_NORMAL);
+}
+
 //Decrypt a FIRM ExeFS
 void decryptExeFs(u8 *inbuf)
 {

source/crypto.h

@@ -105,5 +105,6 @@ extern FirmwareSource firmSource;
 
 void ctrNandInit(void);
 u32 ctrNandRead(u32 sector, u32 sectorCount, u8 *outbuf);
+void setRSAMod0DerivedKeys(void);
 void decryptExeFs(u8 *inbuf);
 void arm9Loader(u8 *arm9Section, u32 mode);

source/firm.c

@@ -305,6 +305,10 @@ static inline void patchNativeFirm(FirmwareSource nandType, u32 emuHeader, A9LHM
         is90Firm = memcmp(section[2].hash, firm90Hash, 0x10) == 0;
     }
 
+    //Sets the 7.x NCCH KeyX and the 6.x gamecard save data KeyY
+    if(a9lhMode == NO_A9LH)
+        setRSAMod0DerivedKeys();
+    
     //Find the Process9 .code location, size and memory address
     u32 process9Size,
         process9MemAddr;