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→Savegame keyY
==== Savegame keyY ====
==== Savegame keyY ====
All gamecard and SD savegames are encrypted with AES-CTR. The base CTR for gamecard savegames is all-zero. The gamecard savegame [[AES|keyslots]]' keyY(these savegame keyslots use the hardware key-scrambler) is unique for each region and for each game. The [[NCSD]] partition flags determine the method used to generate this keyY. When the save [[NCSD]] flags checked by the running NATIVE_FIRM are all-zero, the system will use the repeating CTR, otherwise a proper CTR which never repeats within the image is used. When all of the flags checked by the running NATIVE_FIRM are clear, the keyY(original keyY method used with saves where the CTR repeats within the image) is the following: the first 8-bytes from the decrypted [[NCCH#CXI|CXI]] accessdesc signature + two u32 cardIDs read from gamecard commands.
All gamecard and SD savegames are encrypted with AES-CTR. The base CTR for gamecard savegames is all-zero. The gamecard savegame [[AES|keyslots]]' keyY(these savegame keyslots use the hardware key-generator) is unique for each region and for each game. The [[NCSD]] partition flags determine the method used to generate this keyY. When the save [[NCSD]] flags checked by the running NATIVE_FIRM are all-zero, the system will use the repeating CTR, otherwise a proper CTR which never repeats within the image is used.
The [[AES]]-MAC(which uses a hardware key-scrambler keyslot, as mentioned above) at the the beginning of the savegame must match the calculated MAC using the DISA/DIFF data, otherwise the savegame is considered corrupted(see below).
The [[AES]]-MAC(which uses a hardware key-generator keyslot, as mentioned above) at the the beginning of the savegame must match the calculated MAC using the DISA/DIFF data, otherwise the savegame is considered corrupted(see below).
When all of the flags checked by the running NATIVE_FIRM are clear, the keyY(original keyY method used with saves where the CTR repeats within the image) is the following:
{| class="wikitable" border="1"
|-
! Offset
! Size
! Description
|-
| 0x0
| 0x8
| First 8-bytes from the plaintext [[NCCH#CXI|CXI]] accessdesc signature.
|-
| 0x8
| 0x4
| u32 CardID0 from [[Gamecards|gamecard]] plaintext-mode command 0x90, Process9 reads this with the [[NTRCARD]] hw. The actual cmdID used by Process9 is different since Process9 reads it with the gamecard in encrypted-mode.
|-
| 0xC
| 0x4
| u32 CardID1 from [[Gamecards|gamecard]] plaintext-mode command 0xA0, Process9 reads this with the [[NTRCARD]] hw. The actual cmdID used by Process9 is different since Process9 reads it with the gamecard in encrypted-mode.
|}
===== [[2.0.0-2]] Hashed keyY and [[2.2.0-4]] Savegame Encryption =====
===== [[2.0.0-2]] Hashed keyY and [[2.2.0-4]] Savegame Encryption =====