Do you know, use the same encryption but different structure.
The encryption its easy, use plain encryption xoring...
To get the key in this type of method its easy, only open the file with a hex editor,
and when you see a number repeats a lot this is the key to xor them because, if you xor to 0 then the result is the key...xD once xor the bytes, convert to ascii and now you can see the names., etc..
If you take a look you see a byte before text in stditem.dat...that byte is the length of the name of the
current item...
for easy look, save it the result to file and open again usin hex editor..
then try to look for start position to start decoding the structure, the rest of data could be the filled values... you need to decode field size, if is a byte, short, integer, long values to fill correctly and when finish with the first entry go next following byte to byte..
You need to recreate the structure once decrypted to match to your fields to fill them.
Have a nice learning..