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From: tj@mks.UUCP (T. J. Thompson)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Protecting against copying from hard disks
Message-ID: <170@mks.UUCP>
Date: Tue, 18-Nov-86 14:05:14 EST
Article-I.D.: mks.170
Posted: Tue Nov 18 14:05:14 1986
Date-Received: Tue, 18-Nov-86 23:45:57 EST
References: <836@ur-tut.UUCP>
Organization: Mortice Kern Systems Inc., Waterloo, Ont.
Lines: 40
Keywords: DOS hard disk copy protection
Summary: Cannot be done

In article <836@ur-tut.UUCP> akk2@ur-tut.UUCP (A Kacker) writes:
>What we would like to be able to [do] is
>to somehow make it difficult for users to copy anything off of our hard disks.
>Two things come to my mind on ways of implementing this :
>
>1. If only there was a way to set an attribute of the program to 
>   'protected' a la macintosh programs, that would come up with a 
>    message saying that this program can not be copied.
>
>2. Another way would be to somehow modify DOS so that copying from
>   C: was disabled. If COPY had been an external command, a batch file
>   would have done the job.
>
I replied to the original author indicating the impracticality of implementing
any effective copy protection scheme. I was subsequently distressed to see
several postings suggesting ways of implementing notion 2 above. This is worse
than useless; because it wastes the administrator's time to achieve a totally
false sense of security; and because it only encourages users to defeat the
scheme, since they are no longer on their honour, and circumvention of the
scheme is TRIVIAL.
My first inclination to bypass this so-called protection was to write a program:
it is simple enough that i would even do it with the `a' command in debug, and
not even save it in a file (and i habitually eschew assembler). For someone less
inclined to quick hacks the program is still trivial in C or even BASIC.
But for the naive user it is even easier! She can simply use debug as a copy
program (this is left as a simple exercise for the reader; just remember that
a .exe cannot be directly written out). So the system administrator removes
all copies of debug (draconian, but right in line with modifying EVERY copy
of command.com (including any that users may privately own)).
Then the naive user simply resorts to backup and restore; all it costs her is
another diskette. So the SA banishes all copies of backup...
Then our user, losing naivete, opens up the DOS manual and discovers assign
and subst (again, the use of these to circumvent a copy program checking for
a source of C:... is left as an exercise). So the SA banishes...
Then the poor user struggles through the development of her first program;
so the SA banishes all compilers and interpreters...

Trevor John Thompson	{allegra|decvax|ihnp4}!watmath!mks!tj