ROM Hack ASM help

[mystery01]

I'm new to ASM and I'd like to try it out on something. In a game, some files are encrypted using the game's custom encryption. How would I find out how to decrypt the files?

 

[FAST6191]

Encryption, compression or just a custom file format?

Could I get the name of the game, encrypted/tweaked/mirrored/custom formatted/redundant memory locations for cheat prevention and the like is nothing new as is hashing of save files but full fledged encryption on a file basis would be.
Anyhow if it is encryption or compression you should be able to snatch the unencrypted/uncompressed data from the ram (certainly no ram level encryption there and by similar action I doubt the game devs will leave encrypted data in the ram), the DS does not have much power so I doubt you will see anything other than a basic symmetrical encryption (probably something as simple as short key XOR).

Still ASM,
http://nocash.emubase.de/gbatek.htm#dscart...ryptionfirmware
http://www.coranac.com/tonc/text/toc.htm
http://imrannazar.com/The-Smallest-NDS-File
http://quirkygba.blogspot.com/2008/12/thin...know-about.html

See also the rom hacking docs in the top of the forum, we had a big discussion on assembly once.

 

[mystery01]

You ignored me last time I requested this. Let me refresh your memory. Megaman Star Force 3. Parts labeled as GSM are encrypted messages. The rom even uses the custom encryption instead of LZSS in most cases.

 

[DarthNemesis]

You ignored me last time I requested this. Let me refresh your memory. Megaman Star Force 3. Parts labeled as GSM are encrypted messages. The rom even uses the custom encryption instead of LZSS in most cases.

Who would want to help you after a response like that?