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.

An example .CIA can be downloaded here [1] Credit: Jl12. It includes a .cia file, the .cia file in its extracted form, a screenshot of the application working and some information given by the 3DS.

Format

The CIA format has a similar structure to the WAD format.

The file is represented in little-endian.

The data is aligned in 64 byte blocks (if a content ends at the middle of the block, the next content will begin from a new block).

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	0x02	Type
0x06	0x02	Version
0x08	0x04	Certificate chain size
0x0C	0x04	Ticket size
0x10	0x04	TMD file size
0x14	0x04	Icon size (0 if no icon)
0x18	0x04	APP file size
0x1C	0x04	0x80000000

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
• Icon - (is not a necessary component and can be removed without altering the validity of the file)

The APP data can be either encrypted or cleartext, retail Download Play CIAs' APP data is always encrypted.

Icon

The actual icon is located at offset 0x400 in the icon data.