DAT (Ever17)

Seen/used in the follow game(s):

• Ever17

Structure

Header
Size	Content	Description
4Bytes	Magic/ID
4Bytes	File Count
8Bytes	0x00 Filler
Index
Size	Content	Description
4Bytes	Offset	Starts from zero.
4Bytes	File Size	Stored value is actual size doubled
24Bytes	File name

Notes for 'wallpaper.dat' Extracting images straight from the container file will produce broken images. There is nothing wrong with the extraction process but rather the files themselves. Starting from offset 4352 and ending at 4608 in every single JPG, this 256 byte has been modified in some way.

There is a subroutine in the EXE that will take 1 byte from the JPG that is stored in memory, subtracted it by a number, then put it back. It does this 256 times, or the whole 256 byte chunk of data that is obstructed and only for locations between 4352 and 4608. The number that is subtracted from the raw value is not the same for each byte.

Subtraction numbers are generated by adding up the 14 characters in the file name and using only 8-bits of the result (such as if the total amount ended up needing 2 bytes to display, it just uses one). This is the first difference number out of 256. The next difference number, and the rest of the difference numbers for that matter, are generated by using the previous number in a series of calculations.

'a' starts off as the value of the previous number.

Order	Expression
1	d = a + (a*2)
2	d = d + (d*8)
3	a = a+(d*4)+1243

Current task-> Rewrite archive tool for packing and unpacking. Fix flaws in wallpaper fix tool. Also think about renamming wallpaper fix tool if other files extracted show same thing, such as scripts.