I wrote my own protection routines to limit the number of runs and usage time. Basically each time the software is launched it writes to the registry. Re-installion won't help since the values are still in the registry. Uninstall programs won't break protection because registry-writing is not part of the installation procedure. Both the number of runs and installation date are recorded in a non-obvious format. I also record these in a local table and compare them to registry values to detect things like backdating. For an added security measure, I also check then number of records in a key table to make sure they are under a certain max.

As for encryption, you can do some search and you'll find a lot of algorithms out there. I suspect you're only trying to keep users from breaking the demo so a simple algorithm should suffice.

Mon

>?? could anyone recommend a utility or method for controlling
> any or all of these aspects of demo software use:
>
>1) limiting the # times or length of time it can be used
>2) encrypting or obscuring data structures
>3) encrypting or hiding readable code
>4) preventing unlimited re-installs.
>
>would be very interested in suggestions.
>
>thanks