>What a great idea!
>
>I wish I'd thought of this earlier!
>
>How many people here use hard disk serial numbers to control installations? What methods do you use to control security?
>
>David Turnedge
>Sydney, Australia

I take a less heavy-handed method to control security in my apps. Since I dispise programs that don't allow me to re-install software, or move it to a new machine readily, I've decided to SHAME the user into compliance with licensing (I picked up the idea from a program called ThumbsPlus):

Upon registration, the user reports the company name. I then issue a serial number. The serial number AND the company name (spelling and capitalization have to be exact) are put into the registry (or an INI file). When the program is started, and sometimes while running, the user's company name is prominantly displayed.

The trick is, the program does some mathematical magic on the company name to convert certain characters to a serial number, and appends the allowable license count - all encoded. If the serial number does not match the encoded company name, the program reverts to a trial version.

The result is, if someone gives away the program, they know that their name will forever be associated with the pirated copy - and the recipient is reminded every time they start the program that it doesn't belong to them.

OTOH, if a user's machine crashes they can simply re-install or restore from backup with no hassle.

Also, if the user requests more licenses, I simply regenerate a serial number which includes a new license count. The serialization is sufficiently randomized so that the user will probably not notice any pattern, even after many new serial numbers.

I've used the method for Visual Basic code, and intend to use it in VFP as well.

FWIW.....
Michael