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| ==== FIRM ==== | | ==== FIRM ==== |
| For New3DS firmwares (NATIVE_FIRM, TWL_FIRM, ..), the ARM9 binary has an additional layer of crypto. At the end of each ARM9 binary, there's a plaintext loader.
| | New3DS FIRM uses an additional crypto layer on the ARM9 FIRM section via a loader at the end of the ARM9 binary, see [[FIRM|here]]. |
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| If (u8*)0x10000000 bit 1 is clear (which means that this happens only on hard reboots), it does the following things:
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| * Hashes data from the region 0x10012000-0x10012090 using SHA2.
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| * Initializes AES keyslot 0x11 keyX, keyY to the lower and higher portion of that hash, respectively.
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| * Decrypts arm9_bin_buf+0 using keyslot 0x11, and initialises keyX for keyslot 0x15 with it.
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| * Initialises KeyX for keyslots 0x18-0x20 with the output of encrypting a certain binary sequence using keyslot 0x11. These are presumably New3DS-specific keys.
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| 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.
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| Thus, the ARM9 binary has the following header:
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| {| class="wikitable" border="1"
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| |-
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| ! OFFSET
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| ! SIZE
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| ! DESCRIPTION
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| |-
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| | 0x000
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| | 16
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| | Encrypted KeyX (same for all FIRM's)
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| |- | |
| | 0x010
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| | 16
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| | KeyY
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| |-
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| | 0x020
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| | 16
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| | IV
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| |-
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| | 0x030
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| | 16
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| | ?
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| |-
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| | 0x040
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| | 16
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| | Control block
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| |}
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| =See Also= | | =See Also= |