Hello Lady! xp3 encryption help

[niconiconi]

Hello guys.

I want to do a translation project of this novel but I'm having troubles with the engine.

I managed to extract the text without any problem, but this novel uses the rsa key encryption and I have problems repacking.

Here you have the files and the exe.

 

data.xp3 and data.xp3.sig

http://www.mediafire.com/download/nea7aqt9i9p7b2i/Data.rar

 

.exe

https://www.dropbox.com/s/8qseid82wionaye/%E3%83%8F%E3%83%AD%E3%83%BC%E3%83%BB%E3%83%AC%E3%83%87%E3%82%A3%EF%BC%81.exe?dl=0

 

Hope that you can help me.

[Kelebek1]

Yeah xAzure PM'd me about it. The encryption itself is easy to do, but there's just too many possibilities for me to do manually. There's 0x7F (127) possible keys that can be generated, and they're all from hard-coded numbers.

 

If someone were to do it (properly), then they'd want to log the function call at 0x1E0011C2 (edi at the call and eax at the return). Edi is the adlr & 0x7F, and the least significant byte of the returned eax is what's used to decrypt the first (adler & 0x1BB) + 0x4B8 bytes of the file. Then the adler is shifted right by 16 and then the same function as above is called, and the rest of the file is decrypted. The decrypt itself is just a simple xor on each byte.

 

But even when I hard-coded an adler that I got the right keys for, and checked that the decrypted file wasn't gibberish in the game, it was still throwing errors at me and I have no idea why. *Maybe* it has that stupid tiny thing where a single byte somewhere in the file is extra xor'd, somewhere in my head I'm vaguely remembering seeing that. I didn't check the decrypted file that specifically, so I'm not entirely sure. Binaryfail should be able to make a prog to dump all the return keys to build a table with all the encryption bytes needed and figure it out.

[niconiconi]

It's solved thanks to binaryfail xD

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