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The cleverest floppy disc protection ever? Western Security Ltd

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Re: The cleverest floppy disc protection ever? Western Security Ltd

#121

Post by OnlyMortal »

karmakaze wrote: post #30
csl wrote: post #14

Very clever and great article! But it sounds pretty easy to write a cracker for it: Just rewrite the machine code to jump over the check. Or did I miss anything? Edit: Guess it depends on the details and amount of "obfuscation" that he mentions.

My thoughts exactly. I spent a good amount of time learning about and cracking various schemes. It was never about distribution but about bragging rights and the different ways code was obfuscated. Most were disappointingly simple, others had more layers, very rarely found ones that needed special effort beyond say a person-day or two to solve.

Skate Or Die in the C64 was tricky as it had self modifying code for obfuscation. Took me a while to “debug” that.

The copy protection of Ocean games was much easier to crack. They had a “IsOkToRun” type of function which returned 1 in the A register.

Re: The cleverest floppy disc protection ever? Western Security Ltd

#122

Post by mnw21cam »

anthk wrote: post #83
carapace wrote: post #5

Who recalls the provenance of this old legend about the fellow who challenged his pal to decode a certain floppy? It was a bog-standard DOS boot disk (IIRC) that he could put in his machine and boot normally. But his pal put it in his computer and... nothing doing, no boot. Analysis of the floppy availed not. The challenge went unmet. What did our hero do to make the floppy? .esrever ni nups evird eht os ytiralop eti…

Use rot13 instead of rev.

It was relevant for the joke.

Re: The cleverest floppy disc protection ever? Western Security Ltd

#123

Post by mnw21cam »

tomc1985 wrote: post #69

Is "disc" British English? I have always understood "disk" to mean a floppy disk or hard disk (as short for diskette), and "disc" to refer to circular discs like CDs. (Yes, disks have discs inside them but they are squareish to hold) Seeing people refer to floppy disks as discs really bugs me for some reason.

Seeing people refer to hard drives as "disks" bugs me as well, because they aren't by any stretch of the imagination diskettes.

Re: The cleverest floppy disc protection ever? Western Security Ltd

#125

Post by carapace »

Dylan16807 wrote: post #120
eps wrote: post #112

Earlier quoted context omitted.

It's a good story and you are nitpicking.

I was complaining about the framing, not the story. The story is fine as a story.

I didn't want to make up details. I'm asking if anyone recalls the origin ("provenance") of the original story.

IIRC, the friend did various things to the disk to try to figure out what was up.

Think how crazy this magic trick was: you can literally watch it boot a machine, but then put it in another machine and it's just garbage, that should be impossible...

Re: The cleverest floppy disc protection ever? Western Security Ltd

#126

Post by AlbertoGP »

acomjean wrote: post #62

Its all very clever. Till it doesn't work. A long time ago, we got EA's "seven cities of gold" from my parents for apple. My brothers and I were all excited but it would start to load then the drive would make a strange sound and it didn't work. We exchanged at the local software store, the next one did the same thing.. We tried on a friends apple //c and it worked there. Our //e drives must have been slightly out of…

I had the same experience with some of the games I bought. I ended up having to get a pirate copy and overwrite the original tape or later disk.

Re: The cleverest floppy disc protection ever? Western Security Ltd

#127

Post by Doxin »

szc wrote: post #95
rightbyte wrote: post #13

Earlier quoted context omitted.

Would that work for CDs too?

I don't think so, CDs have a spiral track, so the spiral would also have to be reversed.

Presumably if you'd also flip the phases on the head stepper and move any relevant endstops around you might be able to convince the drive to read disks inside-out.

Fairly sure it'd immediately give up due to pregroove shenanigans but it's an amusing idea.

Re: The cleverest floppy disc protection ever? Western Security Ltd

#128

Post by pickledcods »

outworlder wrote: post #63
csl wrote: post #14

Very clever and great article! But it sounds pretty easy to write a cracker for it: Just rewrite the machine code to jump over the check. Or did I miss anything? Edit: Guess it depends on the details and amount of "obfuscation" that he mentions.

> Just rewrite the machine code to jump over the check Sure. It's even easier today: not only we have specialized software for cracking things, but we can even dump the memory contents and inspect them, patch up while the program is paused, and then rewind and try again from the same location. If we mess up, we can quite easily restart, just run the program again from our fast NVME drives(it will probably come straig…

Or... what I also encountered and found to be the hardest to reverse engineer, having a block decode in the interrupt vector table using all registers including stack pointers as decode keys.

That meant that making a mistake would result in a tedious re-iteration.

Re: The cleverest floppy disc protection ever? Western Security Ltd

#129

Post by m-p-3 »

acomjean wrote: post #62

Its all very clever. Till it doesn't work. A long time ago, we got EA's "seven cities of gold" from my parents for apple. My brothers and I were all excited but it would start to load then the drive would make a strange sound and it didn't work. We exchanged at the local software store, the next one did the same thing.. We tried on a friends apple //c and it worked there. Our //e drives must have been slightly out of…

The joys of DRMs affecting legitimate users..

Re: The cleverest floppy disc protection ever? Western Security Ltd

#130

Post by unionpivo »

m463 wrote: post #103
ev1 wrote: post #98

Earlier quoted context omitted.

Did people not just search it on whateever engine was available at the time? (Yahoo?)

ha :) This was the dark ages, when people could lose phone numbers, forget birthdays and when stuck in a game - suffer without hints or cheat codes.

hey some of us manage to forget birthdays even nowadays.

It just takes a bit more work :)

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