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From: jbn@glacier.ARPA (John B. Nagle)
Newsgroups: comp.sys.ibm.pc
Subject: Re: A dream about breaking copy protection !
Message-ID: <14376@glacier.ARPA>
Date: Fri, 26-Dec-86 17:52:57 EST
Article-I.D.: glacier.14376
Posted: Fri Dec 26 17:52:57 1986
Date-Received: Fri, 26-Dec-86 22:35:29 EST
References: <161@tiger.Princeton.EDU> <1366@nicmad.UUCP> <107@mas1.UUCP> <1162@whuts.UUCP>
Distribution: world
Organization: Stanford University, IC Laboratory
Lines: 62
Summary: Copy protection schemes that work


      There are a number of copy protection schemes that actually work, and
they are not usually recognized as such.  The most effective one is building
your own incompatible machine for your software; this strategy is used by
a number of vendors of expensive turnkey CAD systems, such as Computervision
and Intergraph.  One can similarly require that a special card which performs
some useful function be installed in a standard machine before the software
will run; Cubicomp uses this approach by requiring their own display
card.  These approaches work because the functionality of the special-purpose 
hardware must somehow be provided before the software will run, and doing
so effectively with nothing but emulation software may not be possible.

       Such strategies can be broken by building suitable cards and boxes;
although reverse-engineering custom VLSI chips is difficult, it can
be done and there are places that do it.  This is beyond the capabilities
of the typical hacker, but not outside the range of abilities of some of the
low-cost clone makers in the Far East.  There exist PC clones which contain
copies of the IBM ROM BIOS; such machines represent a breaking of IBM's
strategy for protecting their software by building it into their hardware.
Entry of such machines into the U.S. is illegal but there are countries that
don't prohibit such things.  

       Another strategy that will work for a while is putting the software
in a CD-ROM.  Yes, you can copy it, but to what?  If the program has
been deliberately constructed to need huge data files (imagine having the
help files stored as uncompressed color raster images) the cost of enough
magnetic disk space to store the data may exceed the cost of the program.
This is probably a temporary situation; historically, whenever optical
storage seemed to be on the threshold of acceptance, the magnetic storage
people came up with some new way to increase density and killed off another
generation of optical technology.  Digital audio tape is already threatening
the compact disk, and only heavy lobbying by the music industry has delayed
its introduction in the U.S.

       It is worth noting that the digital audio tape standard has been
made deliberately incompatible with compact disks, so that a digital to
digital copy is not possible by straightforward means; the sampling rates
are different.  This did not happen by accident; there were major fights
in the industry and the software (i.e. music) people won out over the
hardware (i.e. equipment manufacturers), partly by threatening to have
legislation enacted taxing blank tape or recorders.
  
     In the video world, copy protection is making a big comeback,
in the form of "Macrovision", a scheme for introducing some junk data in
the vertical interval which confuses standard VHS VCR recording
synchronization circuits.  Something like 30% of new video releases are
now copy protected, and the percentage is increasing.  Few consumers are
aware of this; there has been little publicity.  Interestingly, Macrovision
could in theory be applied to broadcast signals.  Macrovision can be
beaten by several methods, of which the simplest is copying to a Beta
machine.  But most people lack the proper equipment.

       Ever see a VCR with two tape drives?  No?  Wonder why?  Again, it's
not by accident, but due to heavy lobbying from the motion picture industry.

      In time, the software industry may get more political clout, and we
may well see hardware support for copy protection schemes in time.  With
the right support, the protection mechanism could be made totally invisible
to the authorized user.  We may yet see this happen.  I would give it about
even odds of happening in the next five to ten years.

				John Nagle