Savegames: Difference between revisions

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Revision as of 00:29, 3 October 2018

This page describes the format of save files contained in NAND. These files are stored as completely unencrypted, plaintext data. Save files are not cleared upon creation, resulting in possible garbage data in unused portions of the container.

Main header

The header is 0x4000 bytes long.

There are 2 headers stored at 0x0 and 0x4000, presumably for commit and rollback purposes.

Image offset Length Description
0x000 0x100 AES-CMAC header
0x100 0x200 DISF header
0x300 0x44 Duplex header
0x344 0xC4 Integrity verification header
0x408 0x200 Journal header
0x608 0x48 Save header
0x650 0x40 Main data remap header
0x690 0x40 Meta data remap header
0x6D0 0x8 Unknown
0x6D8 0x200 Extra data A
0x8D8 0x200 Extra data B
0xAD8 0x3528 Additional storage

The additional storage at the end of the header is used to store any extra header data. This data's structure is determined by offsets stored in the main part of the header.

AES CMAC header

Image offset Length Description
0x00 0x10 AES-CMAC over DISF header (size 0x200)
0x10 0xF0 Zero padding

The final CMAC key used for this is generated using GenerateAesKek with a kek source and the device key, along with and LoadAesKey and a set key seed.

DISF

This section contains information about the structure of the save file.

Start Length Description
0x000 4 Magic ("DISF")
0x004 4 Version? (Upper 2 bytes must be 0x0004)
0x008 32 Hash of start of DPFS to end of 0x4000 block (0x300-0x3FFF)
0x028 8 Main data remap mapping table offset
0x030 8 Main data remap mapping table size
0x038 8 Meta data remap mapping table offset
0x040 8 Meta data remap mapping table size
0x048 8 Main data remap offset
0x050 8 Main data remap size
0x058 8 Duplex level 1 virtual offset A
0x060 8 Duplex level 1 virtual offset B
0x068 8 Duplex level 1 size
0x070 8 Duplex level 2 virtual offset A
0x078 8 Duplex level 2 virtual offset B
0x080 8 Duplex level 2 size
0x088 8 Journal storage virtual offset
0x090 8 Journal storage data size A
0x098 8 Journal storage data size B
0x0A0 8 Journal storage journal size
0x0A8 8 Duplex master bitmap offset A
0x0B0 8 Duplex master bitmap offset B
0x0B8 8 Duplex master bitmap size
0x0C0 8 IVFC master hash offset A
0x0C8 8 IVFC master hash offset B
0x0D0 8 IVFC master hash size
0x0D8 8 Journal block table virtual offset
0x0E0 8 Journal block table size
0x0E8 8 Virtual offset of bitmap of modified physical journal blocks
0x0F0 8 Size of bitmap of modified physical journal blocks
0x0F8 8 Virtual offset of bitmap of modified virtual journal blocks
0x100 8 Size of bitmap of modified virtual journal blocks
0x108 8 Virtual offset of bitmap of free journal blocks
0x110 8 Size of bitmap of free journal blocks
0x118 8 IVFC level 1 virtual offset
0x120 8 IVFC level 1 size
0x128 8 IVFC level 2 virtual offset
0x130 8 IVFC level 2 size
0x138 8 IVFC level 3 virtual offset
0x140 8 IVFC level 3 size
0x148 8 File allocation table virtual offset
0x150 8 File allocation table size
0x158 1 Index of the active duplex master bitmap
0x200 End

Duplex header

  • Block sizes are stored as powers of 2
Start Length Description
0x00 4 Magic ("DPFS")
0x04 4 Version? (Upper 2 bytes must be 0x0001)
0x08 8 Master bitmap offset
0x10 8 Master bitmap size
0x18 4 Master bitmap block size power
0x1C 8 Level 1 offset
0x24 8 Level 1 size
0x2C 4 Level 1 block size power
0x30 8 Level 2 offset
0x38 8 Level 2 size
0x40 4 Level 2 block size power

Integrity verification header

  • Offsets for levels 1-3 come from the metadata remap storage
  • Offsets for level 4 comes from the main data remap storage
  • This is the same header used in NCA files
Start Length Description
0x00 4 Magic ("IVFC")
0x04 4 Version? (Upper 2 bytes must be 0x0002)
0x08 4 Master hash size
0xC 4 Number of levels (Unused in save files)
0x10 0x18*6 Level information for up to 6 levels
0xA0 32 Salt seed

Level information

  • 0x18 bytes long
  • Block sizes are stored as powers of 2
Start Length Description
0x00 8 Offset
0x08 8 Size
0x10 4 Block size power
0x14 4 Reserved

Journal header

Start Length Description
0x00 4 Magic ("JNGL")
0x04 4 Version? (Must be 0x10000 or less)
0x08 8 Total size (Incl. journal)
0x10 8 Journal size
0x18 8 Block size
The below fields are treated as a separate subheader
0x20 4 Version? (Must be 0 or 1)
0x24 4 Main data block count
0x28 8 Journal block count
0x200 End

Save FS header

  • Structure is different than 3DS.
Start Length Description
0x00 4 Magic ("SAVE")
0x04 4 Version? (Upper 2 bytes must be 0x0006)
0x08 8 Number of blocks. Does not change if save file is resized.
0x10 8 Block Size
The below fields are treated as a separate subheader
0x18 8 Block size
0x20 8 FAT offset
0x28 4 FAT entry count
0x2C 4 Padding
0x30 8 Data offset
0x38 4 Data block count
0x3C 4 Padding
0x40 8 Directory table block index
0x48 8 File table block index

Remap storage header

Start Length Description
0x00 4 Magic ("RMAP")
0x04 4 Version? (Must be 0x10000 or less)
0x08 4 Number of remapping entries
0x0C 4 Number of remapping segments
0x0C 4 Number of bits reserved for the segment index in virtual offsets
0x40 End

Extra data

Start Length Description
0x00 0x40 Save Struct
0x40 8 Save owner ID
0x48 8 Timestamp
0x50 4 Unknown
0x54 4 Unused?
0x58 8 Size of usable save data
0x60 8 Journal size
0x200 End

Files

Directory Table Entry

  • Index 0 is the start of a linked list that contains all invalid/inactive directories.
  • Index 1 is the start of a linked list that contains all valid/active directories.
  • Index 2 is the root directory.
Start Length Description
0x00 4 Parent directory node index
0x04 64 Filename
0x44 4 Next sibling directory node index
0x48 4 First child directory node index
0x4c 8 First child file node index
0x54 8 Unused?
0x5c 4 Next directory node index in the chain of invalid or valid directories. If this is the first block in a list of length 0, this value will contain the total number of directory nodes.

File Table Entry

  • Index 0 is the start of a linked list that contains all invalid/inactive files.
  • Index 1 is the start of a linked list that contains all valid/active files.
Start Length Description
0x00 4 Parent directory node index
0x04 64 Filename
0x44 4 Next sibling file node index
0x48 4 Index of the block that the file starts at
0x4c 8 File size in bytes
0x54 8 Unused?
0x5c 4 Next file node index in the chain of invalid or valid files. If this is the first block in a list of length 0, this value will contain the total number of file nodes.
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