> Many a crack back in the day was even more simple still, we'd just find and alter the right JE or JNE into a JMP and we're off to the races.

I did that with dBASE III, which used ProLok "laser protection" from Vault Corporation - a signature burned onto the diskette with a laser. Back then, I found it amazing that Ashton-Tate actually spent money to contract with a copy protection company for something that could be so easily defeated by a teenager reading assembler.

They could have easily just written the same kind of code themselves. An example of the power of marketing over substance.

I was able to replicate that protection mechanism just by scratching a diskette with a pin. The "laser" was a meaninglessly advanced-sounding solution that added no value compared to any other means of damaging a diskette.

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Aaargh20318 4 hours ago | parent | next [-]

I remember doing something similar with Lemmings 3D. You could simply NOP over the JMP into the copy-protection subroutine. It was surprisingly easy.

Made me feel like such a badass hacker at 15 years old.

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foresto 4 hours ago | parent | prev | next [-]

> I was able to replicate that protection mechanism just by scratching a diskette with a pin.

How did you figure out where to scratch it? Was the laser mark visible on the original disk, or did you have to read the code and orient based on the diskette's index hole?

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anyfoo 4 hours ago | parent | next [-]

Yes, it was apparently very visible: https://martypc.blogspot.com/2024/09/pc-floppy-copy-protecti...

But as I mentioned in a sibling comment, I’m not sure it was ever confirmed that it was really a laser that made that mark.

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antonvs 3 hours ago | parent | prev [-]

I described two different scenarios: defeating the protection, and replicating it, e.g. to protect your own software without paying Vault for their "laser" protection.

Defeating the protection didn't involve knowing anything about the laser mark - as the comment I replied to described, it just involved changing a conditional jump to an unconditional one.

Replicating the protection involved causing minor damage on the diskette - the details don't really matter, laser, pin scratch, whatever - then formatting the disk, and registering the pattern of bad sectors created by the damage. A normal copy of the disk didn't replicate those bad sectors exactly, which made it possible to detect that the original disk was not present.

	▲	lstodd an hour ago \| parent [-]
		Ha! I remember disk copy programs which read these bad sector patterns and then replicated the error pattern in software (not on physical disk obviously). Similar stuff was later used for CDs IIRC.

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anyfoo 4 hours ago | parent | prev [-]

Was ist ever confirmed that it was in fact a laser? I wanted to make a trivia question out of this ProLok protection, because “lasers for copy protection” sounds just weird enough to potentially be a nonsense answer without context, but I couldn’t confirm that the holes were indeed made with lasers, and not with other means.

	▲	antonvs 3 hours ago \| parent [-]
		Good question. I don't know the answer, but I'm quite certain that it didn't really matter what mechanism was used to mark a diskette. Any damage would be equally strong as a way to detect copying.