Difference between revisions of "Savegames"

Revision as of 03:59, 30 September 2018

This page describes the format of savegames contained in NAND. NAND savegames do not use an container with the entire file encrypted. Various areas of the saveimage is uninitialized data, resulting in encrypted data in those areas (like 3DS did).

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	Magic Number (0x40000)
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	Magic Number (0x10000)
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	Magic Number (0x20000)
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	Magic Number (0x10000 or less)
0x08	8	Total size (Incl. journal)
0x10	8	Journal size
0x18	8	Block size
0x20	4	Unknown (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	Magic Number (0x60000)
0x08	8	Number of blocks. Does not change if save file is resized.
0x10	8	Block Size
		The below fields are read separately from the above fields
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

There are generally two RMAP blocks in sequence.

Start	Length	Description
0x00	4	Magic ("RMAP")
0x04	4	Magic Number (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

Files

File Offset Table

Indexes 0 and 1 are reserved to point towards the folder and file tables.

File Offset Table Entry

Start	Length	Description
0x00	3	Data offset, in blocks
0x03	1	Unknown, 80
0x04	4	Unknown, 0

File/Folder Table Entry

The root file/folder index is generally 2

Start	Length	Description
0x00	4	Parent Folder Index
0x04	64	Filename
0x44	4	File/Folder Index?
0x48	4	File offset index in offset table, 0 for folders
0x4c	8	File size, or number of files for folders
0x54	8	Unknown
0x5c	4	Next File Index, same as folder index for folders

@@ Line 502: / Line 502: @@
 |}
-=== RMAP ===
+=== Remap storage header ===
 * There are generally two RMAP blocks in sequence.
@@ Line 518: / Line 518: @@
 | 0x04
 | 4
-| Magic Number (0x10000)
+| Magic Number (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
 |}