shai hess wrote:
HI,
I found two points which I can address to have some protection in assembler
code.
I think you are wasting your time. There are both commercial and
free (cbttape.org) debug programs that can load your code and
execute it, and trace instruction flow step by step. You might
be able to detect that this is happening, but there are many
variants to guard against..... And when they are detected in the
trace, can be bypassed.
While instruction tracing is highly useful in many cases, CBT
has a number of disassemblers. Anything you put into a load
module I can read off disk, and analyze. If you look at some CBT
contributions, you will find a number of useful programs that
were originally distributed only in object or load-module
format, that some enterprising minds have disassembled and
cleaned up for use (we all owe a great debt to Bill Godfrey,
among others, for his work with IBM type 3 and 4 programs). If
your program is less than 32K in size, I could probably
duplicate its source in workable form in less than a month. Also
there are enough individuals on this forum who could read your
documentation, and produce a reasonable facsimile of your
program in about that time.
Your only real protection is to place legal restrictions on the
code, and embed copyright and trademark notices everywhere. As
noted elsewhere, corporations tend to be responsible about their
licenses. Determined hackers you cannot protect against.
Gerhard Postpischil
Bradford, VT
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