XCI
Header
The header is 0x200-bytes, at Gamecard+0.
| Offset | Size | Description |
|---|---|---|
| 0x0 | 0x100 | RSA-2048 PKCS #1 signature over the data from 0x100 - 0x200. |
| 0x100 | 0x4 | Magicnum "HEAD" |
| 0x104 | 0x4 | Offset of Secure partition (Size of non-secure data?), in Media Units (0x200 bytes for switch gamecarts) |
| 0x108 | 0x4 | 0xFFFFFFFF |
| 0x10C | 0x1 | ? |
| 0x10D | 0x1 | Cartridge Size. 0xF8 = 2 GB, 0xF0 = 4 GB, 0xE0 = 8 GB, 0xE1 = 16 GB |
| 0x10E | 0x1 | ? |
| 0x10F | 0x1 | ? |
| 0x110 | 0x8 | ? |
| 0x118 | 0x8 | Size of the Gamecart, in Media Units |
| 0x120 | 0x10 | ? |
| 0x130 | 0x8 | Offset of HFS0 FS partition |
| 0x138 | 8 | HFS0 Header size |
| 0x140 | 0x20 | SHA256 hash of the HFS0 Header |
| 0x160 | 0x20 | SHA256 hash of the crypto header |
| 0x180 | 0x4 | 1? |
| 0x184 | 0x4 | 2? |
| 0x188 | 0x4 | 0? |
| 0x18C | 0x4 | Offset of Secure partition (Size of non-secure data?), in Media Units, again. |
| 0x190 | 0x70 | Encrypted data/hashes of some kind |
Cert
This is for the CERT, located at Gamecard + 0x7000 (always?). This matches exactly the output from fsp-srv IDeviceOperator cmd 206 "GetGameCardDeviceCertificate".
| Offset | Size | Description |
|---|---|---|
| 0x0 | 0x100 | RSA-2048 PKCS #1 signature over the data from 0x100 - 0x200. |
| 0x100 | 0x4 | Magicnum "CERT" |
| 0x110 | 0x10 | ? |
| 0x12A | 0xD6 | Encrypted data. Some kind of key? |
The data between the CERT and the start of the HFS0 is all 0xFF.
HFS0
This is the FS which has magicnum "HFS0" at header+0.
| Offset | Size | Description |
|---|---|---|
| 0x0 | 0x4 | HFS0 Magic |
| 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 | SHA256 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?).
Typical Cartridge Layout
Observed gamecarts 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.