Content.bin file structure
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These are the details of the Content.bin file structure.
VC games and Wii channels, when saved to a SD card, will be stored in a file named "private/wii/title/XXXX/content.bin", where XXXX is the four-character name of the game/channel.
A program to help parse and analyze the structure of content.bin files: parse-channel.c. Put it in the same directory as a compiled version of Segher's Wii.git tools, since it depends on them.
General layout
The general layout of this file is as follows. Most of the data here is sketchy, at best.
Template:Table Template:Table/Header Template:Table/Row Template:Table/Row Template:Table/Row Template:Table/Row Template:Table/Row Template:Table/Row |}
Part A: Encrypted header
The header is encrypted by the SD key and SD IV. When decrypted, it contains the following structure: (* means the field is discussed below)
Template:Table Template:Table/Header Template:Table/Row Template:Table/Row Template:Table/Row Template:Table/Row Template:Table/Row Template:Table/Row Template:Table/Row Template:Table/Row Template:Table/Row Template:Table/Row Template:Table/Row Template:Table/Row Template:Table/Row Template:Table/Row Template:Table/Row Template:Table/Row Template:Table/Row Template:Table/Row |}
- unknown_2
This value looks almost like the four-letter code of a channel/game. I have found HADP on most files, but HAGP on Super Mario/NES and '\0UPD' (that is, the first byte is 00, then UPD) on two N64-games.
- Title-ID-reference_1 and Title-ID-reference_2
These two looks like two Title-ID:s. On most files I have analyzed they are: 00 01 00 08 HALP and 00 01 00 08 HAKP (this is from a PAL Wii). However, on Super Mario/NES I found 00 01 00 02 HAFP and 00 01 00 02 HAGA. A guess is that they might stipulate some kind of dependencies on system files.
- Zeroes_1
If the guess about depencencies is correct, then this might be a padding field which is zero only if not more than two dependencies are needed.
- IMET data
The IMET data follows a quite strict format, with a few changes between files. I don't have any good idea what those changes represent. The only major difference is found i Metroid Prime 3 Preview, which have everyting zero except the "IMET" header. The values indicated below is for all other files I've studied, which was non-zero.
Template:Table Template:Table/Header Template:Table/Row Template:Table/Row Template:Table/Row Template:Table/Row |}
- Padding (normally zero)
For Metroid Prime 3 Preview, this field was not completely zero. The three bytes with positions 0x313, 0x367 and 0x3BB was 0x20 instead of 0. My guess is that this doesn't matter, but then again, it could have something to do with the weird IMET data of MP3preview.
Part B: Encrypted icon
This part is is also encrypted by the SD key and SD IV. It contains a small header followed by LZ77 compressed data. The compressed data is the icon.bin portion of opening.bnr for the title.
Part C: Cleartext "Bk" header
This part is not encrypted. It is similar to the Bk header found in savegames, but the contents only partially match. The header could also be exactly 0x80 long; the size of 0x70 is a guess based on the first field being a size parameter.
Template:Table Template:Table/Header Template:Table/Row Template:Table/Row Template:Table/Row Template:Table/Row Template:Table/Row Template:Table/Row |}
Part D: Cleartext TMD block
This part is not encrypted. It is well described on the TMD file format page. Some things to note:
- Only the tmd struct is included here, not the certificates.
- As described on the TMD file format page, after the main struct (with a size of 0x1E4), there follows an array of content_record structs.
- There is as many structs as the num_contents field in the tmd struct indicates. For VC, this seems to be always 7.
- The type and size file of the content_record is of special interest, since they describe part E.
- If type is 0x80 0x01, then the content is included in part E, and the size of the content is given by the size field.
- Otherwise, type will be 0x00 0x01, and the content is (presumably) shared between VCs and stored elsewere on the Wii.
Part E: Encrypted data contents
This part is encrypted. The encryption key is currently unknown. It might be unique to the Wii which saved the VC. It consists of several separate "files", one for each of the contents with the 0x80 type flag in the TMD content_record, padded to 64-byte boundary.
- This part is probably the same for every Wii, but unique to each VC. It's probably encrypted with the title key, stored in a ticket somewhere. Bushing 03:42, 11 February 2008 (PST)
Part F: Cleartext certificates
This part is not encrypted. The exact details of this field is not yet analyzed, but it is likely related to the chain of certificates as described on the TMD file format page.