Subject: Re: Cracking games
From: [email-masked] (-~=Zaphod=~-)
Date: 26 Nov 92 13:27:42 GMT
Newsgroups: comp.sys.amiga.programmer

In article <[email-masked]> [email-masked] writes:

>I'd like to know how cracking games is done.  Not because I want to
>crack them & copy them, but because I want to learn how one can trace
>the adresses to rip out graphics and music.  I want to try to program a
>decent mod-ripper or graphic-ripper, but i need to understand this
>first.  Someone mentioned a disassembler and doing something-rather.. I
>can't recall.  Can someone please help?  Thanks.

To crack games you will need:

1.Hardware reference manual.
2.An indepth knowledge of the amiga and the way it works.
3.An in depth of 68000 assembly language.
4.Amiga disk drives inside and out. (Shows you how to do MFM loaders.)

Most games are protected by using one long track for each sector.
The loader for this disk format is stored on the boot block, which will
always be readable, this is where most of the cracking takes place.

I won't tell you exactly how its done, because there are some people who don't
take kindly to this kind of thing.

In a nut-shell you must:

1..Use a dissembler on the boot block.
2..Find out how long the tracks are. (Search for the disk registers.)
3..Write an assembly language program that mimics the loader, but after 
   reading the track in, it writes it in amiga dos format to another disk.
   After you've done this you will have a copy or the original in amiga
   dos format. It won't work as it is.
4..You must now use a dissembler on the new boot block, change the loader
   from loading a protected disk, to loading amiga dos tracks.
   Forget the trackdisk.device, most of the hardware will have been
   tampered with.

If your disk does not work, then the chances are that the disk protection
has been changed after loading the program.

Getting rid of password protection is done by searching for the text, then
searching for a routine that access the address of the text, though the
text is usually coded with exclusive ORs.

I'm not sure what you could use the graphics/sound for though, if you are
writting a demo, you get no brownie points for originality.

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