Bit of an encryption problem..

[yuppicide]

I don't even know if this is possible.

 

I play a game called Combat Arms. It's a free war game. In game you can set options for your keys, BUT you can't set the left and right arrow keys for "strafe left" and "strafe right". I've been playing these types of games for nearly 20 years now and I use arrow keys, not a W A S D key setup. I hate that!

 

So, I found out that you could edit player.txt file and remove the value for left and right, and add a value to strafeleft and straferight. The only problem was that when a new patch came out for the game you'd have to do this process all over again. Here's my old player.txt file:

 

player.txt

 

With the latest patch released a few days ago it seems they've encrypted the file and you can no longer edit it! I'm a paying customer of theirs (I did say it was a free game before, but if you want you can purchase items as well), so I lodged a complaint through their support system, the BBB, and on their website forums. So far there is no answer and no fix in sight.

 

Is there anyway to find out what kind of encryption this uses and possibly unencrypt it or reencrypt so I can change strafeleft and straferight?

 

I have tried a program to rebind keys, which I've rebinded my left arrow to A and my right arrow to D, but that did not work because in that player.txt file you need to get rid of the values in LEFT and RIGHT in order to make it work then add values to strafeleft and straferight.

 

Here's a copy of the encrypted file:

 

player.txt

[RevEng]

A well encrypted file is indistinguishable from random bits, and this one pretty much fits the bill...

 

1. all 256 ascii chars are represented in roughly uniform quantity

2. the unix file command doen't identify it, or any of the contents. I wrote a quick script which strips off one byte at a time and reruns "file" on the result. Nada.

3. the file isn't compressable.

 

If I had to guess, I'd guess it's plaintext xor'ed with random data, but it should be easy enough to check. If you modify one of the parameters in the game, compared to the original player.txt, does the resulting player.txt file...

 

1. ...change one or two bytes in the middle of the file.

2. ...change a byte and all following bytes in the file.

3. ...completely change the whole file.

 

#1 would imply a simple xor with random data. #2 would imply a chain block cipher (or less likely, a stream cipher). #3 would imply a large-sized block cipher, or something akin.

 

Either way, the game itself needs to decrypt the file to read it. Given the right tools you'd be able to figure out what's going on.

Edited June 3, 2009 by RevEng