NPA

Used in the following game(s):

• Demonbane
• Steins;Gate

May be more than one version and possibly using one or more methods for obstructing data.

Structure

Overall
Size	Content	Description
4 Bytes	Index Size
? Bytes	Protected Index Data
? Bytes	Protected File Data

Index
Size	Content	Description
4 Bytes	File count
Index Entry
4 Bytes	Filename Length
? Bytes	Filename
4 Bytes	File Size?
4 Bytes	Offset?
4 Bytes	Unknown

Research

The index data is protected. The way the program reads and processes this space is by first loading 4 bytes at the start of the file that is the size of the protected index. It then loads the whole index into memory. It then puts some data into the XMM0 register, which looks like the key. So far, it looks like it's static but I'll have to check if that's true for other files. It then enters the main decoding loop and loads 16 bytes into the next register, XMM1. It then XOR XMM1 by XMM0. It then puts the decoded part back into memory.

Some notes about structure. File names appear to be 2 byte char strings (wstrings?).

Key = BD AA BC B4 AB B6 BC B4