FIRM: Difference between revisions
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== [[New_3DS]] FIRM == | |||
For New3DS firmwares (NATIVE_FIRM, TWL_FIRM, ..), the ARM9 FIRM binary has an additional layer of crypto. At the end of each ARM9 binary, there's a plaintext loader. The format of the FIRM header is identical to regular 3DS FIRM(the RSA modulo is the same as regular 3DS too). | |||
If (u8*)0x10000000 bit 1 is clear (which means that this happens only on hard reboots), it does the following things: | |||
* Hashes data from the region 0x10012000-0x10012090 using SHA2. | |||
* Initializes AES keyslot 0x11 keyX, keyY to the lower and higher portion of that hash, respectively. | |||
* Decrypts arm9_bin_buf+0 using keyslot 0x11, and initialises keyX for keyslot 0x15 with it. | |||
* Initialises KeyX for keyslots 0x18-0x20 with the output of encrypting a certain binary sequence using keyslot 0x11. These are presumably New3DS-specific keys. | |||
It sets KeyY for keyslot 0x15 to arm9_bin_buf+16, the IV to arm9_bin_buf+32. It then proceeds to decrypt the binary. When done, it decrypts arm9_bit_buf+64 using a fixed key and makes sure it's all zeroes. It it is, it jumps to the decrypted addr. Otherwise it will just loop forever. | |||
Thus, the ARM9 binary has the following header: | |||
{| class="wikitable" border="1" | |||
|- | |||
! OFFSET | |||
! SIZE | |||
! DESCRIPTION | |||
|- | |||
| 0x000 | |||
| 16 | |||
| Encrypted KeyX (same for all FIRM's) | |||
|- | |||
| 0x010 | |||
| 16 | |||
| KeyY | |||
|- | |||
| 0x020 | |||
| 16 | |||
| IV | |||
|- | |||
| 0x030 | |||
| 16 | |||
| ? | |||
|- | |||
| 0x040 | |||
| 16 | |||
| Control block | |||
|} | |} | ||