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DATA.BIN

PSP_GAME/USRDIR/DATA.BIN holds every game file: a table of block numbers, then the files, each padded to a 2048-byte block. The disc stores it encrypted. Read and written by mhp_formats.databin.DataBin (decrypted) and decrypt/encrypt, which need the iso extra.

Layout (decrypted)

A block is 2048 bytes. The table occupies the first whole blocks; the files follow back to back.

Offset Type Meaning
0x00 u32[n + 1] Start block of each file, then the end block (the archive's length in blocks). Word 0 is file 0's start, so it is also the table's length in blocks
{u32 id, u32 size}[] Exact byte sizes, for the files that record one
bytes Fill up to the end of the table's last block; the games leave leftover memory here
  • File i is data[start[i] * 2048 : start[i + 1] * 2048]: its bytes, then padding to the block (shipped padding is not always zero; to_bytes writes zeros). A file without a size record is known only to the block.
  • The start words ascend, and the first word equal to the total block count ends them.
  • The size records have no count. They run while the ids ascend and each size lies inside its file's last block; the first pair that breaks either rule is fill.
  • Writing (DataBin.to_bytes): a replacement may have any length. It is padded to whole blocks, every later file moves, and DataBin.replace updates the file's size record. The last file cannot be empty, or the table would lose it.

File ids

DataBin.files[i] is engine file id i. mhp-formats extract writes engine file i as data_files/file_{i-1:05d}.<ext> and skips file 0, so an extracted name is one below the id the engine asks for (mhfu.files.ENGINE_SKEW). The extension comes from the magic: .tmh, .pmf, .wav, .vag, else .bin.

Where things are, in extracted ids (mhfu.files):

What Function Example
A species' model PAC monster_pac(species) Tigrex, species 75: file_06185
A big monster's AI overlay em_overlay(species)
st<NNN>.pac, stage<NNN>.ovl stage_pac(stage), stage_overlay(stage) snowy base camp st098: file_05905
The hub's st046 variants stage_variant_pac(variant)
In-quest engine, map table, hub overlays GAME_TASK, GAME_SUB, LOBBY_TASK

An MHP3rd monster's model PAC is followed by its geometry companion (+1) and its moveset (+2) (mhfu_port.records.GEO, ANIM).

Encryption

The cipher is mhef's DataCipher. Game.MHFU selects its key set MHP2G_EU, Game.MHP3RD selects MHP3_JP; the key set only decides which files are stored plain.

  • The table is enciphered as one run seeded with block 0. Read the first word alone to learn the table's length.
  • Each file is one run seeded with its own start block. The files on the key set's exception list (by engine file id) are stored plain.

A run, per u32 word, from the seed's high and low halves k0, k1 (a zero half becomes 0x2345 or 0x7F8D):

k0 = k0 * 0x2345 % 0xFFD9
k1 = k1 * 0x7F8D % 0xFFF1
word ^= k0 << 16 | k1

Encryption XORs and then substitutes every byte through mhef's encode table; decryption substitutes through the decode table and then XORs.

Extracting a game

uv run mhp-formats extract game.iso extracted/

copies the image's files and DATA.BIN's decrypted files into extracted/data_files/. The game is identified by the product code in UMD_DATA.BIN; only the two releases above are accepted.