Re: How do I - Compile a number into the program

From: Guy Cohen (support_at_mcam2u.com)
Date: 05/17/04 

Date: Mon, 17 May 2004 16:25:25 +0200

Where will I find the bits?
Is it a simple task?
If yes - might be that my user will do the same.
Is there a better way to "protect" my software?
TIA
Guy

??"Larry Serflaten" <serflaten@usinternet.com> ??? ??????
news:ukfYsFBPEHA.624@TK2MSFTNGP11.phx.gbl...
>
> "Guy Cohen" <support@mcam2u.com> wrote
> > The product is software+hardware.
> > Lets say I want to provide a software on a CD that will work only with a
> > unique device (modem for example).
>
> I would suggest you use a second program to modify the bits in a
> copy of the exe.
>
> It seems you'll have a device with a unique number, and you want to
> test for that number in your program. So, leave space in your program
> for the number, and use a second program to insert that number into the
> program after it is compiled.
>
> You would then only need to run that second program, and enter the
> unique number which will cause it to make a copy of the exe with that
> number added. You then copy that exe to the CD, and send it off.
> There would be no need to recompile the program for different numbers.
>
> How do you leave space in your program? That depends on how
> secure you need to be. Plus the code to check the number has to
> be well hid, also (possibly in several paces) But for a simple method,
> add a long string of Chr(127) in a module somewhere. When the
> program is compiled, look through the file to find that string of
> characters. When you find it, replace the first character with your
> first digit, and take the difference of that digit and 127, and add that
> to the last character. Take the second digit and put it in the second
> position and take the difference of that digit and 127 and add that
> to the second to last character.
>
> You basically alter the first part of the string to the required digits
> and alter the last part of the string to keep the two 127's balanced
> so that the checksum for that section remains the same as it started.
>
> If you know you need ten digits then make it a 25 character string,
> or so, and when you go to test, only grab the first ten digits of
> the string....
>
> LFS
>

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