NPA

Used in the following game(s):

• Demonbane
• Steins;Gate

Structure

Overall
Size	Content	Description
4 Bytes	Index Size
x Bytes	Index Data (protected)
x Bytes	File Data (protected)

Index Header
Size	Content	Description
4 Bytes	File count	Number of index entries
Index Entry
4 Bytes	Filename Length
? Bytes	Filename	Each character is 2 bytes
4 Bytes	File Size
4 Bytes	Offset
4 Bytes	Unknown	Always 0x00000000

Addition Notes

This format obscures the data it stores. Both the index and data are protected in the same way. The first data read is 4 bytes at the start of the file. This is the size of the index and it's value is not obscured. Next the full index is read into memory and decoded by XOR'ing it by the key. Once the index is processed, data can be loaded but the data is protected the same way the index is, XOR'ed by a key. The game makes use of the XMM registers (SSE) and the assembly code ends up being a small, tight loop with just a few assembly instructions such as MOVDQA and PXOR. Unsure what the C++ equivalent would be. Probably uses some libraries I'm not used to but if I can find those, compile a sample program and disassemble it, might be able to make a more optimized program. Although for a extractor/packing program, speed or efficiency is more or less irrelevant baring extreme cases.

Key	Game(s)
BD AA BC B4 AB B6 BC B4	Steins;Gate (JAST USA)

• Only one game has been tested so it is an assumption that there can be different keys thus a list of specific games and the key they used will be recorded here.

Tools

Coming soon...