[Semaphor]

I’ll never forget the crack that I downloaded back in the days. It came with a PDF or image of a CD you were supposed to print, so you could drill through the burned CD at exactly the proper position. This was supposed to defeat the hardware dongle the software otherwise required. Can’t remember what software it was and never tried it to find out if this was a prank or actually worked, but I loved that as a kid :D

[rasz]

There is no angle position sensor on the CD, and only one continuous track. This could work if you burned multisession CD, scratched at some specific radius of the first session, followed by coding that information into executable burned in the second session.

https://scarybeastsecurity.blogspot.com/2020/06/weak-bits-fl...

http://dmweb.free.fr/?q=node/210

http://dmweb.free.fr/?q=node/1429

https://scarybeastsecurity.blogspot.com/2020/07/turning-400-...

This one describes very similar floppy protection - encoding physical disk parameters in the executable per every individual disk. https://scarybeastsecurity.blogspot.com/2020/12/the-cleveres...

[Agentlien]

That sounds unlikely to work. I had a professor at the university who started his lecture on ECC by saying he always drilled a hole in all his CDs since he knew it would work anyway.

Or perhaps the ECC simply works well enough that there's no perceptible data loss for audio?

[a-dub]

i think your leg was being pulled.

that said, one of the first copy protection schemes involved writing specific sectors to a magnetic disk with an invalid checksum. when the program would start, it would verify that reading those sectors would return an error, but if you used a regular disk copy program it would not copy the invalid sectors- either resulting in an aborted copy or a copy that would zero out the bad sectors on the target which would not produce the expected read errors on startup telling the program it had been copied.

[aasasd]

Wouldn't the CD explode soon after it got to speed? This happened plenty to discs that were just not made uniformly enough.