Author: Michael Cummings
Date: 00:03:11 10/11/00
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On October 10, 2000 at 16:56:40, Dave Gomboc wrote: >On October 10, 2000 at 15:41:27, Andrew Dados wrote: > >>There is one old and clever technique to 100% copy-protect a CD, but expensive. >>It would require building custom burners for making original cds. >> >>The concept is to burn some part of track (lets call it a sector) with very poor >>quality, so average read on that sector will give you errors. You'll need some >>500 reads and average them to get 'true' content. Statistical analysis over many >>reads can be used to proof originality. > >People used to protect games that were distributed on floppy disks in very >similar ways. In fact, the more programmable the disk drive, the wackier things >copy protectors would get it to do. I've seen software access track 255 on the >floppy drives that were used with the commodore 64. Keep in mind now that on a >normally-formatted disk for the 1540/1541 drives there were 35 tracks, and >trying to move the head to read track 255 would break your disk drive. Needless >to say, the track gap had been altered so that several tracks all partially >overlapped each other. This also had the side effect that if a program was dumb >enough to try to read and write tracks 1, 2, 3, 4 ... instead of tracks 1, 12, >19, 34 ... that the data would be misread and miscopied. > >All in all, the bottom line is that the devices are not constructed to be >read-only for some portions of the media, so if you can read a disc recorded in >some funky format, you can replicate it. > >Of course, this doesn't even consider that someone will simply write a crack to >skip the code that is intended to verify that the copy protection is in place. >I still recall with fondness one warez bragg that I read as a kid: "Copy >protection in a routine! Dumbest idea yet!" Today, I'd imagine that more people >licence or outsource their copy-protection code than ever. > >>There are other ways to make a custom CD impossible to copy in a burner. (Like >>write a replacement driver to understand checksums in a different way. Normal >>driver could not read such a CD). Another way is to access small data stub >>prewritten on a blank CD in factory. Or write your own iso-9660 replacement :) > >The same argument applies here. If you can do it, so can somebody else. Okay, >maybe nobody would bother just for a chess program, but for something used >regularly and consistently (e.g. SDMI for future audio recordings), expect it to >not take long! Maybe it won't play on SDMI-compliant devices (due to hardware >features), but it will play on everything else! > >>-Andrew- > >Dave Someone will make software to adapt to all these possililities, if it not already out there it soon will. I have yet to find a program that is protected. Playstation games (Sony Corp) are suppose to have the best and most advanced copy protection on their cd's. I have yet come accross one I could not copy with my software and cd burner.
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