Implementing time-limit in a program

[Bill]

What is a good way to implement a time-limit in a program, so that it stops
functioning after a given amount of days? I was thinking of using the registry,
but if I just save a date or a number of days, it is easy to change.

Any ideas?

Thanks,

/BiLL.

[David Crowell]

You can store a hash of the value also. If the value doesn't match the
hash, then you know it's been tampered with.

<plug>
or you could check out my CSecurity product at www.davidcrowell.com
</plug>

Dave


"Bill" <bill@billnet.nu> wrote in message news:3961aa06$1@news.devx.com...
>
> What is a good way to implement a time-limit in a program, so that it
stops
> functioning after a given amount of days? I was thinking of using the
registry,
> but if I just save a date or a number of days, it is easy to change.
>
> Any ideas?
>
> Thanks,
>
> /BiLL.

[Sylvain Forget]

Yes use the registry and just encrypt the date with a key only you know. And
just decrypt it to verify how many days it's been.

"Bill" <bill@billnet.nu> wrote:
>
>What is a good way to implement a time-limit in a program, so that it stops
>functioning after a given amount of days? I was thinking of using the registry,
>but if I just save a date or a number of days, it is easy to change.
>
>Any ideas?
>
>Thanks,
>
>/BiLL.