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When I was a teenager I used to enjoy playing computer games. However the copy protection was really annoying as you couldn't back up the expensive game disks a
by nickcw 3y ago
When I was a teenager I used to enjoy playing computer games. However the copy protection was really annoying as you couldn't back up the expensive game disks and floppy disks weren't exactly reliable then. So I taught myself how to crack copy protection.
I did some 6502 (BBC Micro) games but mostly 68000 (Atari ST). The process was quite similar to the article but I never cracked anything that complicated! Nor did I keep detailed records - I was far to worried about them being evidence to be used against me.
My best crack was working out that I didn't need to figure out how to read the key to decrypt the game from the secret uncopyable protected sector on the disk (I think it had a deliberate CRC error in it so the standard disk firmware wouldn't read it). I disassembled the crypto routine and saw that it just did a simple XOR of the key block over and over again. I then used a frequency analysis on the encrypted game binary to recover the secret key and decrypt the game!
I came to enjoy cracking the copy protection much more than playing the game as it was like having an intellectual battle with the developer. In fact after that playing games lost its appeal and I moved on to creating new things on the computer instead.
I never distributed my cracks though - I was far too frightened of getting caught!
- OnlyMortal 3y agoI was a C64 cracker and added intros (with ripped Rob Hubbard tunes and border sprite scrollers). Much of the disk protection was laughable, Ocean games been an example. They had a routine that would return 1 in the A register so the crack was to load the accumulator with 1, do a nop to fill the gap and continue I could crack their games in about a minute with a disk sector editor I wrote that would disassemble the game on disk by reading the sectors for the game. The hardest crack I did was EA’s Skate or Die. It had self modifying code in the copy protection which took quite a while to unwind loops. I also cracked Ghosts and Goblins, or maybe it was Ghosts and Ghouls, on the Amiga. The chumps who made the disk left the source code to the boot loader on the disk as a deleted file. I undeleted it and “fixed” the boot loader. Oddly, I worked in copy protection many years later.
- ddingus 3y agoThat is funny! One lame scheme I ran into was a basic try to load deliberately bad sector check. If bad, run game. If good, fail. But, they did not check for any specific error! Any error would do to start the game, which was ULTIMA 2. Because of that, anyone could copy the game disk and cause a disk read error to happen at the right time to play the game. The easiest thing to do was open the drive door, wait a bit, then close it to see the game load normally.
- OnlyMortal 3y agoIt sounds similar to the Ocean protection which did a disk check. It was, essentially a: bool IsGenuineDisk() { return DiskHasSecretStuff(); }
- ddingus 3y agoLol, yeah. That was my first "crack." I happened to run the game on an Atari computer, which makes sounds during disk I/O. I could hear the sectors, hear the fail, retry, then remaining sectors load. So, count em up, open the door, listen for fail, close, go! Didn't even need a single hex value to accomplish. After that, I got into it on an Apple. Reading this brings back memories. That particular machine is a lot of fun, and it is fun because almost everything is software. Totally open.