Difference between revisions of "XCI"

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(RE'd from GameCardWriter)
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−
= Header =
+
Known internally as "XCI" (NX Card Image), this is the format used for storing the contents of a Nintendo Switch Gamecard.
−
The header is 0x200-bytes at offset 0 in the Gamecard.
+
 
 +
= Gamecard Header =
 +
This header is 0x200 bytes and is located at offset 0 in the Gamecard.
  
 
{| class="wikitable" border="1"
 
{| class="wikitable" border="1"
Line 10: Line 12:
 
| 0x0
 
| 0x0
 
| 0x100
 
| 0x100
−
| RSA-2048 PKCS #1 signature over the XCI header (data from 0x100 to 0x200)
+
| RSA-2048 PKCS #1 signature over the header (data from 0x100 to 0x200)
 
|-
 
|-
 
| 0x100
 
| 0x100
Line 26: Line 28:
 
| 0x10C
 
| 0x10C
 
| 0x1
 
| 0x1
−
| ?
+
| KEK Index
 
|-
 
|-
 
| 0x10D
 
| 0x10D
Line 42: Line 44:
 
| 0x110
 
| 0x110
 
| 0x8
 
| 0x8
−
| ?
+
| Random value for challenge–response authentication
 
|-
 
|-
 
| 0x118
 
| 0x118
Line 50: Line 52:
 
| 0x120
 
| 0x120
 
| 0x10
 
| 0x10
−
| Gamecard Initial Data IV (reversed)
+
| Gamecard Info IV (reversed)
 
|-
 
|-
 
| 0x130
 
| 0x130
Line 62: Line 64:
 
| 0x140
 
| 0x140
 
| 0x20
 
| 0x20
−
| SHA256 hash of the HFS0 Header
+
| SHA-256 hash of the [[#HFS0 Header|HFS0 Header]]
 
|-
 
|-
 
| 0x160
 
| 0x160
 
| 0x20
 
| 0x20
−
| SHA256 hash of the crypto header
+
| SHA-256 hash of the [[#Initial Data|Initial Data]]
 
|-
 
|-
 
| 0x180
 
| 0x180
 
| 0x4
 
| 0x4
−
| 1?
+
| Secure Mode Flag (0x01 means Secure Mode is available)
 
|-
 
|-
 
| 0x184
 
| 0x184
Line 86: Line 88:
 
| 0x190
 
| 0x190
 
| 0x70
 
| 0x70
−
| Gamecard Initial Data (AES-128-CBC encrypted)
+
| [[#Gamecard Info|Gamecard Info]] (AES-128-CBC encrypted)
 
|}
 
|}
  
−
= Cert =
+
== Gamecard Info ==
−
This is for the CERT, located at Gamecard + 0x7000 (always?). This matches exactly the output from fsp-srv IDeviceOperator cmd 206 "GetGameCardDeviceCertificate".
+
When decrypted, this 0x70 byte region is as follows:
 +
 
 +
{| class="wikitable" border="1"
 +
|-
 +
! Offset
 +
! Size
 +
! Description
 +
|-
 +
| 0x0
 +
| 0x4
 +
| Version (0x01 for old Gamecards, 0x02 for new Gamecards with the "logo" partition)
 +
|-
 +
| 0x4
 +
| 0x4
 +
| Empty
 +
|-
 +
| 0x8
 +
| 0x4
 +
| Always 0x00A10010 (unfinalized Gamecard) or 0x00A10011 (finalized Gamecard)
 +
|-
 +
| 0xC
 +
| 0x4
 +
| Always 0x1388
 +
|-
 +
| 0x10
 +
| 0xC
 +
| Empty
 +
|-
 +
| 0x1C
 +
| 0x4
 +
| ?
 +
|-
 +
| 0x20
 +
| 0x4
 +
| ?
 +
|-
 +
| 0x24
 +
| 0x4
 +
| Empty
 +
|-
 +
| 0x28
 +
| 0x8
 +
| Random ID?
 +
|-
 +
| 0x30
 +
| 0x8
 +
| Always 0x0100000000000816 (title-listing data archive's title ID)
 +
|-
 +
| 0x38
 +
| 0x38
 +
| Empty
 +
|}
 +
 
 +
= Gamecard Certificate =
 +
This is the Gamecard's unique certificate and is located at offset 0x7000.
 +
 
 +
[[Filesystem_services|FS]] IDeviceOperator cmd 206 "GetGameCardDeviceCertificate" retrieves this data.
  
 
{| class="wikitable" border="1"
 
{| class="wikitable" border="1"
Line 100: Line 158:
 
| 0x0
 
| 0x0
 
| 0x100
 
| 0x100
−
| RSA-2048 PKCS #1 signature over the data from 0x100 - 0x200.
+
| RSA-2048 PKCS #1 signature over the data from 0x100 to 0x200
 
|-
 
|-
 
| 0x100
 
| 0x100
Line 108: Line 166:
 
| 0x110
 
| 0x110
 
| 0x10
 
| 0x10
 +
| ?
 +
|-
 +
| 0x120
 +
| 0xA
 
| ?
 
| ?
 
|-
 
|-
Line 115: Line 177:
 
|}
 
|}
  
−
The data between the CERT and the start of the HFS0 is all 0xFF.
+
The data between the Gamecard Certificate and the start of the HFS0 region is all 0xFF.
 +
 
 +
= Initial Data =
 +
This data is used for challenge–response authentication when changing to the Gamecard's secure mode.
 +
 
 +
[[Filesystem_services|FS]] calculates a SHA-256 hash over the whole 0x200 bytes and compares it with the hash stored at offset 0x160 in the [[#Gamecard Header|Gamecard Header]].
 +
 
 +
{| class="wikitable" border="1"
 +
|-
 +
! Offset
 +
! Size
 +
! Description
 +
|-
 +
| 0x0
 +
| 0x8
 +
| Random value from [[#Gamecard Header|Gamecard Header]] at offset 0x110
 +
|-
 +
| 0x8
 +
| 0x8
 +
| Empty
 +
|-
 +
| 0x10
 +
| 0x2C
 +
| Challenge–response authentication data
 +
|-
 +
| 0x3C
 +
| 0x1C4
 +
| Reserved (must be empty)
 +
|}
  
 
= HFS0 =
 
= HFS0 =
−
This is the FS which has magicnum "HFS0" at header+0.
+
This is the Gamecard file system which starts with magicnum "HFS0".
 +
 
 +
== Header ==
 +
The "SHA-256 File System" or "HFS0" starts at offset 0xF000 in the Gamecard. The first 0x200 bytes act as a global header and represent the root partition which points to the other partitions ("normal", "logo", "update" and "secure).
 +
 
 +
A hash for this header is stored at offset 0x140 in the [[#Gamecard Header|Gamecard Header]].
 +
 
 +
== File System ==
 +
The actual file system is as follows (also valid for the root partition):
  
 
{| class="wikitable" border="1"
 
{| class="wikitable" border="1"
Line 128: Line 226:
 
| 0x0
 
| 0x0
 
| 0x4
 
| 0x4
−
| HFS0 Magic
+
| Magicnum "HFS0"
 
|-
 
|-
 
| 0x4
 
| 0x4
Line 177: Line 275:
 
| 0x14
 
| 0x14
 
| 0x4
 
| 0x4
−
| Size of Hashed region of file (for HFS0s, this is the size of the pre-filedata portion, for NCAs this is usually 0x200).
+
| Size of Hashed region of file (for HFS0s, this is the size of the pre-filedata portion, for NCAs this is usually 0x200)
 
|-
 
|-
 
| 0x18
 
| 0x18
Line 185: Line 283:
 
| 0x20
 
| 0x20
 
| 0x20
 
| 0x20
−
| SHA256 hash of the first (size of hashed region) bytes of filedata.
+
| SHA-256 hash of the first (size of hashed region) bytes of filedata
 
|}
 
|}
  
 
The string table is 00-padded to align the start of raw filedata with a sector/media unit boundary (usually?).
 
The string table is 00-padded to align the start of raw filedata with a sector/media unit boundary (usually?).
  
−
= Typical Cartridge Layout =
+
= Cartridge Layout =
 
Observed gamecards contain three partitions: "update", "normal", and "secure".
 
Observed gamecards contain three partitions: "update", "normal", and "secure".
  
Line 199: Line 297:
 
The secure partition contains an identical copy of the .cnmt.nca and game icondata nca, as well as all other ncas required for the game.
 
The secure partition contains an identical copy of the .cnmt.nca and game icondata nca, as well as all other ncas required for the game.
  
−
The entire rest of the gamecard after the secure partition ends is all FF padding.
+
The entire rest of the Gamecard after the secure partition ends is all FF padding.
  
 
[4.0.0+] The "normal" partition is now empty and a new partition "logo" was added.
 
[4.0.0+] The "normal" partition is now empty and a new partition "logo" was added.

Revision as of 21:14, 1 June 2018

Known internally as "XCI" (NX Card Image), this is the format used for storing the contents of a Nintendo Switch Gamecard.

Gamecard Header

This header is 0x200 bytes and is located at offset 0 in the Gamecard.

Offset Size Description
0x0 0x100 RSA-2048 PKCS #1 signature over the header (data from 0x100 to 0x200)
0x100 0x4 Magicnum "HEAD"
0x104 0x4 Write Size (size of non-secure data in Media Units which are 0x200 bytes)
0x108 0x4 0xFFFFFFFF
0x10C 0x1 KEK Index
0x10D 0x1 Gamecard Type (0xFA = 1GB, 0xF8 = 2GB, 0xF0 = 4GB, 0xE0 = 8GB, 0xE1 = 16GB, 0xE2 = 32GB)
0x10E 0x1 ?
0x10F 0x1 Gamecard Options (bit0 = AutoBoot, bit1 = HistoryErase)
0x110 0x8 Random value for challenge–response authentication
0x118 0x8 Gamecard Size (in Media Units which are 0x200 bytes)
0x120 0x10 Gamecard Info IV (reversed)
0x130 0x8 HFS0 partition offset
0x138 0x8 HFS0 header size
0x140 0x20 SHA-256 hash of the HFS0 Header
0x160 0x20 SHA-256 hash of the Initial Data
0x180 0x4 Secure Mode Flag (0x01 means Secure Mode is available)
0x184 0x4 2?
0x188 0x4 0?
0x18C 0x4 Duplicate Write Size (size of non-secure data in Media Units which are 0x200 bytes)
0x190 0x70 Gamecard Info (AES-128-CBC encrypted)

Gamecard Info

When decrypted, this 0x70 byte region is as follows:

Offset Size Description
0x0 0x4 Version (0x01 for old Gamecards, 0x02 for new Gamecards with the "logo" partition)
0x4 0x4 Empty
0x8 0x4 Always 0x00A10010 (unfinalized Gamecard) or 0x00A10011 (finalized Gamecard)
0xC 0x4 Always 0x1388
0x10 0xC Empty
0x1C 0x4 ?
0x20 0x4 ?
0x24 0x4 Empty
0x28 0x8 Random ID?
0x30 0x8 Always 0x0100000000000816 (title-listing data archive's title ID)
0x38 0x38 Empty

Gamecard Certificate

This is the Gamecard's unique certificate and is located at offset 0x7000.

FS IDeviceOperator cmd 206 "GetGameCardDeviceCertificate" retrieves this data.

Offset Size Description
0x0 0x100 RSA-2048 PKCS #1 signature over the data from 0x100 to 0x200
0x100 0x4 Magicnum "CERT"
0x110 0x10 ?
0x120 0xA ?
0x12A 0xD6 Encrypted data. Some kind of key?

The data between the Gamecard Certificate and the start of the HFS0 region is all 0xFF.

Initial Data

This data is used for challenge–response authentication when changing to the Gamecard's secure mode.

FS calculates a SHA-256 hash over the whole 0x200 bytes and compares it with the hash stored at offset 0x160 in the Gamecard Header.

Offset Size Description
0x0 0x8 Random value from Gamecard Header at offset 0x110
0x8 0x8 Empty
0x10 0x2C Challenge–response authentication data
0x3C 0x1C4 Reserved (must be empty)

HFS0

This is the Gamecard file system which starts with magicnum "HFS0".

Header

The "SHA-256 File System" or "HFS0" starts at offset 0xF000 in the Gamecard. The first 0x200 bytes act as a global header and represent the root partition which points to the other partitions ("normal", "logo", "update" and "secure).

A hash for this header is stored at offset 0x140 in the Gamecard Header.

File System

The actual file system is as follows (also valid for the root partition):

Offset Size Description
0x0 0x4 Magicnum "HFS0"
0x4 0x4 Number of files
0x8 0x4 Size of the string table
0xC 0x4 Zero/Reserved
0x10 X File Entry Table
0x10 + X Y String Table
0x10 + X + Y Z Raw File Data

Where File Entry Table consists of Number of Files FileEntries:

Offset Size Description
0x0 0x8 Offset of file in Data
0x8 0x8 Size of file in Data
0x10 0x4 Offset of filename in String Table
0x14 0x4 Size of Hashed region of file (for HFS0s, this is the size of the pre-filedata portion, for NCAs this is usually 0x200)
0x18 8 Zero/Reserved
0x20 0x20 SHA-256 hash of the first (size of hashed region) bytes of filedata

The string table is 00-padded to align the start of raw filedata with a sector/media unit boundary (usually?).

Cartridge Layout

Observed gamecards contain three partitions: "update", "normal", and "secure".

The update partition (Gamecard partition 0 for fsp-srv cmd 31) contains .cnmt.nca + .nca files for the entire system update required to play the game. Launch day carts contain a full copy of 1.0 ncas, newer carts contain newer sysupdate NCAs etc.

The normal partition contains the .cnmt.nca and the game icondata nca. This is presumably for future compatibility so that if a future update changes the cryptographic protocol for the secure partition, Game icon data can still be shown in the home menu on old firmwares.

The secure partition contains an identical copy of the .cnmt.nca and game icondata nca, as well as all other ncas required for the game.

The entire rest of the Gamecard after the secure partition ends is all FF padding.

[4.0.0+] The "normal" partition is now empty and a new partition "logo" was added.

Retrieved from "https://switchbrew.org/w/index.php?title=XCI&oldid=4725"