We had to build our own copy protection after dongles were hacked and too fussy. Weak bits were copyable using the CopyIIPC option board.
So what we resorted to is using a needle scratching the inner most tracks of the floppy on random locations. Writing those tracks with a pattern and record where the pattern was broken. While executing the program it did write that track and read that track, the locations where the pattern was broken (two tracks, begin and end) was the key that was used to decrypt some parts of the further into the program.
To my knowledge it was never hacked and every disk was unique, we kept the keys for each customer (was part of the serial) so if it was hacked we could trace it to the leaker.
So what we resorted to is using a needle scratching the inner most tracks of the floppy on random locations. Writing those tracks with a pattern and record where the pattern was broken. While executing the program it did write that track and read that track, the locations where the pattern was broken (two tracks, begin and end) was the key that was used to decrypt some parts of the further into the program.
To my knowledge it was never hacked and every disk was unique, we kept the keys for each customer (was part of the serial) so if it was hacked we could trace it to the leaker.