[Share]Phantasy Star IV

Here you go!

Mostly the same as retail coding, but there is a line that appears to be different. Would be sweet if it was something significant like extra XP for early monsters. I checked this one with two retail roms, so hopefully I didn't fudge this one up as well!

http://s000.tinyupload.com/file_upl...156314362&del_id=05209294505801471021&gk=auto

 

Here's the save file it came with for anyone interested. This was found in one of those storage raids:

http://s000.tinyupload.com/file_upl...95125207&del_id=00842945578925497378&gk=1e309

 

This matches the US final but the ROM has been watermarked to Jaime Wojick, who was the product manager for the game.

 

What program can you use to figure that out specifically?

 

There really isn't a program that can do it per se, you have to find the data in the ROM and do it manually. In the ROM header, there's a section dedicated for leaving comments that's located at 0x1C8. Commercial games don't have anything written in there usually, but prototypes sometimes do. For prototypes meant for magazines, someone will often watermark/fingerprint the ROM by writing an encrypted message in the ROM header that identifies who was responsible for managing the prototype (it'll usually either be a name, media outlet, or just the purpose of the build). The message is encrypted with a simple XOR on every byte in the message with a 1 byte key. The key itself can only use values 0-255 (or 0x0-0xFF), so there are only 256 possible keys making it very trivial to crack.You can use an online programmers calculator to XOR each byte to output the message. In Phantasy Star 4's and Vectorman 2's case, the key was 0xF0.

So for example:

Original message (encrypted):
9D 9B 70 9A 91 99 9D 95 70 A7 9F 9A 99 93 9B

Key (to XOR with):
F0

Decrypted message (XOR):
6D 6B 80 6A 61 69 6D 65 80 77 6F 6A 69 63 6B

In ASCII:
mk€jaime€wojick