>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


thanks mon,
received helpful replies from other, advising on products to
do these things, but i like your approach, as it is straightforward
and you know exactly what it is implemented.

additionally,
i wish i could think of a way to hide table structures and content too.
i have one app where those are AS (or more) important that the program
itself. for example, i've take a lot of time to develop a encoding
scheme for certain medical data. the actual end-users don't know how to
pirate that info (other than hand copying it from the tree-list
controls in which it is displayed) ... but they could easily find somebody
to do it for them. i suppose i could encrypt the fields and decrypt
them as i read them in, but that would slow everything down.
????