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From: bcw@duke.UUCP
Newsgroups: net.micro
Subject: Re: Software Piracy and Coupons
Message-ID: <3732@duke.UUCP>
Date: Wed, 9-Nov-83 22:15:01 EST
Article-I.D.: duke.3732
Posted: Wed Nov  9 22:15:01 1983
Date-Received: Fri, 11-Nov-83 08:22:57 EST
Lines: 37

From:	Bruce C. Wright @ Duke University
Re:	Software piracy and coupons

There is so much misinformation flying around the net about this that I
feel I ought to get my two cents worth in.  First of all, as several people
have pointed out, it is not sufficient to write random bits for the "soft"
bits - the scheme relies on re-reading the sectors and seeing *different*
bits on each read.  It might be possible (as one person suggested) to start
with a disk with *all* "soft" bits and then write the good ones over it;
I'm not sure exactly how the scheme is implemented and this might work.
It would still require getting hold of such a pirate disk, though;  it
would still be impossible for the unadjusted disk drive to write such a
disk.  It might be possible for someone quite familiar with disk hardware
to modify the diskette drive to be able to write such bits, though.

All of this has little bearing on whether the proposed scheme is secure.
I doubt very seriously that this scheme will slow down a really dedicated
and knowledgeable pirate, disk drive modifications or no disk drive
modifications.  Personally, I haven't tried to crack any microcomputer
protection schemes, though I've dealt with larger computers for > 10
years and have never seen a foolproof protection scheme.  This goes double
for systems where the user has full access to everything by definition
(as in a personal computer).  The method of attack would be to disassemble
the program and find the place(s) where the checks were made, and remove
them (of course, there may be some other things needed ... such as removing
checksum calculaters and so forth).  This could also be done using tools
such as DEBUG.

The scheme would probably keep out the less knowledgeable pirates pretty
effectively (it would not be subject to things like the nibble copiers
which are now out and which don't require programming knowledge to use),
but for the really sophisticated pirate it would be quite vulnerable, and
once a modified pirate copy appeared it could be copied widely (because
the protection code would be removed, there would be no restrictions on
copying it any more).  Keeping out sophisticated pirates is tough.  Really.

				Bruce C. Wright @ Duke University