Re: How do you protect your C++ applications?

From:
"Ben Voigt" <rbv@nospam.nospam>
Newsgroups:
microsoft.public.vc.language
Date:
Fri, 8 Dec 2006 08:35:29 -0600
Message-ID:
<eQADIYtGHHA.4712@TK2MSFTNGP04.phx.gbl>
"NickP" <a@a.com> wrote in message
news:%23iU6MPrGHHA.1248@TK2MSFTNGP03.phx.gbl...

Hi Ben

   UPX compresses an executable, it does not provide shareware
functionality.


No, but (see OP's post excerpted below) by using compression, UPX will make
it more difficult to disassemble the code, search for plain-text strings,
etc.

"Shareware functionality" isn't much good if a user can simply search your
..exe for plain text strings and find out where the expiration date is
stored, then delete it and reinstall to extend the trial.

UPX will prevent a casual user from doing that so easily.

Most registration key systems can be easily subverted by changing a single
assembly jump instruction from conditional (did the hash compare ok?) to
unconditional, thereby setting all the internal state just as if the key was
found valid.

Nick.

My typical users aren't going to be hackers, nor will the app be of any
interest to hackers, so the encryption doesn't have to br great, just
enough to deter the average user.

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