CIA
Overview
CIA stands for CTR Importable Archive. These files contain a compiled application which can be installed on CTR NAND, TWL NAND (part of the NAND used by DSi applications) and on the SD card. CIA files can be created with the Nintendo 3DS SDK and installed on the 3DS test units by the Dev channel.
Format
The CIA format based on WAD format, so the structure is very similar to the WAD structure. The file is represented in little-endian.
CIA Header
This is a 32 bytes long header (8 x uint32).
| START | SIZE | DESCRIPTION |
|---|---|---|
| 0x00 | 0x04 | Archive Header Size (=0x2020 bytes) (Starts with 0x80 @ offset 0x0020) |
| 0x04 | 0x04 | Reserved = 0 |
| 0x08 | 0x04 | Certificate chain size |
| 0x0C | 0x04 | Ticket size |
| 0x10 | 0x04 | TMD file size |
| 0x14 | 0x04 | Banner size (0 if no banner) |
| 0x18 | 0x04 | Content Size |
| 0x1C | 0x04 | APP file size |
The order of the sections in the header also is the order of them in the CIA file:
- certificate chain
- Ticket
- TMD file data
- APP file data
The data of the files is decrypted.
If you sum up all the fields in the header you get 60 bytes less then the actual file size. (you need to add the 32 bytes of the header).
Question: Where are those 60 bytes at?