Message-ID: <000501bda2bf$11555460$f34e08c3@arthur>
From: "Arthur" <arfa AT clara DOT net>
To: "DJGPP Mailing List" <djgpp AT delorie DOT com>
Subject: Re: This is not a problem but...
Date: Sun, 28 Jun 1998 18:23:50 +0100
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>> When I compile my program, and edit my exe file, I can modify all my
>> strings used with printf.  I don't want people to do so, is there a way
>> to conteract this?
>
>Well, on the ST and Amiga you could get utilities which could compress
>programs. The difference to things like self-extracting ZIPs is that you
>double-click on the program and it decompresses itself (this process is
>invisible to the user), then runs normally. But I don't know if there is
>a thing like this on the PC.


Hee hee, one up for the M68Ks :^)

There is a program in the DJGPP distribution which compresses exes but I've
never used it so I don't know exactly how it works.

The best things about the program packers on the ST and Amiga were that they
compressed a file to about a third of its original size, and wrote a small
stub to the file so that it would uncompress the file to memory as if it had
loaded up normally. This way you could compress any program, not just those
written in a certain language. They also could compress data files and
sistributed the algorithm to uncompress these on the fly, so you could
easily use data compression in your own programs. AFAIK there's nothing on
the PC which can touch these.

A similar idea could be implemented to encrypt the data. but anyone with the
encryption algorithm could easily decrypt the data, change it then encrypt
it again. Having said that, you'll never get around it whatever method you
use - it's the nature of the system.


James Arthur
jaa AT arfa DOT clara DOT net