[thelist] Need to add a serial number system to my ASP script.

Ken Schaefer ken.schaefer at gmail.com
Sun Sep 12 22:59:14 CDT 2004

On Mon, 13 Sep 2004 11:45:19 +0930, Craig <cd-ml at aardvark.net.au> wrote:
> Hi Ken,
> > How are you licencing the code? Per site? Per server? Can the user
> > transfer the licence/software between physical boxes (provided they
> > don't use more than the numbfer of copies they bought?)
> I'm not sure really. I was going to give the user the .DLL file(s) and
> supply them with a serial number that takes the DLL out of "demo mode".
> > For example, if the code is licenced per physical server (irrespective
> > of the number of processors), and the code can be moved between boxes
> > (eg the user upgrades/replaces the box) then I would:
> > a) use assymetric key encryption
> > b) have the user tell you what the IP address of the server is
> > c) create an encrypted config file. The message is the IP address, and
> > key is yourp private key. You give this config file to your user.
> > d) you embed the public key into your application. When the component
> > initialises, it reads in the config file, decrypts it using the public
> > key, and checks the IP address against the IP address the machine is
> > using.
> >
> > This may present issues in a load balanced environment, and isn't
> > circumventable by clever programmers, but it's a common technique that
> > works for most cases.
> At the moment, I think that I won't restrict it by IP address or anything.
> Regarding the serial number, how would I actually implement this? I have VB
> code here that generates a serial number.  What I'm not sure about is when I
> generate a serial number, does it have to decrypt to a certain value, like
> the string "password".  So in my DLL I would decrypt the serial number and
> if the value is "password" I allow the DLL to run.
> Sorry that my explanation is a little vague.

In this case, with a fixed serial number(s), I don't think there's any
real point encrypting anything.

You see, the DLL would need a master list of valid serial numbers. And
it makes no real difference if that list is a set of "encrypted"
serial numbers, or just a set of unencrypted serial numbers.

Your system doesn't aim to prevent copying of the software - only to
prevent the use of software without a serial. By copying the serial,
anyone can copy the software. Whereas in my previous suggestion you
are aiming to prevent the copying of software - in that case, the
software checks machine properties against the serial, however only
you can generate the serial numbers, and the serial number is unique
for each machine.


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