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From: notes@iuvax.UUCP
Newsgroups: net.micro
Subject: Re: Re: Software protection in software - (nf)
Message-ID: <387@iuvax.UUCP>
Date: Wed, 18-Apr-84 01:04:03 EST
Article-I.D.: iuvax.387
Posted: Wed Apr 18 01:04:03 1984
Date-Received: Thu, 19-Apr-84 03:05:58 EST
Sender: notes@iuvax.UUCP
Organization: Indiana University
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#R:amd70:-453900:iuvax:400014:000:827
iuvax!apratt    Apr 17 13:50:00 1984

Sorry, but as long as there are people with disassemblers who can get
read/write access to the code, there is NO safe protection scheme which depends
on the software to implement it.  One padlock on a door can be picked. So can
twenty. It may take longer, but a determined locksmith (pun intended) can
do it. With the right debugger, it could even be automated. Just check for
differences in behavior between a legitimate program and one running on the
"wrong" machine (at the program-trace level, not the user-interface level).
Such checks (padlocks) can ALWAYS be circumvented, as can any safeguards
which check to make sure the padlocks are in place.  Like I said, under
a Von Neumann architecture, you just can't do it.

----
						-- Allan Pratt
					...ihnp4!inuxc!iuvax!apratt
				(please do not respond to iuvax!notes)