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RTC File format (reverse engineering)

Posted: Tue Oct 14, 2025 4:03 pm
by Taghor
So,

Looking at the one drive I see there's alot of RTC dungeons (namely the EOB one) which has the txt file with it but not the graphics.

Poking about in the asm, I've made some progress in determing how the encryption methods are achieved. It's essentially a XOR Cipher stream (keystream XORd against plaintext).

Now, this does not mean I can extract anything... It means I can only see unencrypted binary data (for now).

it's only a personal project, I find these kind of things to be some what of a puzzle, but if anyone's interested I can put it on github..

Re: RTC File format (reverse engineering)

Posted: Tue Oct 14, 2025 10:14 pm
by Gambit37
Reverse engineering RTC!? The circle is now complete. :D

Re: RTC File format (reverse engineering)

Posted: Thu Oct 23, 2025 11:24 pm
by Taghor
Progress!!

I've got the encryption sorted, and now the decompression.

It essentially stores in different sections, HDR, PTY, SAV, MOD ( maybe more )

MOD is where the graphics, sound etc are stored.

I've written some header carving stuff to extract the bitmaps from it and so far it's looking good, extracting BMP and the WAV files

Image

I'll have a look at tidying it up tomorrow, it's doing the decode, decompress stuff in C and the signature carving in c#. I'd like to have it all in C or C# before I put it on github.

Re: RTC File format (reverse engineering)

Posted: Sat Oct 25, 2025 3:22 am
by Taghor
Github repo:
https://github.com/joesblog/RTCExtractor

The codes a mess, its written for use not beauty!

Probably best to just use the release.

Re: RTC File format (reverse engineering)

Posted: Tue Oct 28, 2025 7:24 am
by Sphenx
Wow ! that's impressive. This is working great on several RTC I tried. The decode code looks like magic to me.