Dmitry,

I see, I thought you'll give the nSeed as a key to the user and in your program you compared with the actual value, for example if you gave to the user 382622 (You can even disguise it as 'AB38-26CD-2BX2' where all letters are random and you clear them out) and then in your registration program you test (very crude) if int(rand(tnSeed) * 1000000) = 740233 && Valid Key

Anyways, I do not think this is a good solution, Craig's is much better

>Thank you for your suggestion. The fact that the rand(nseed) returns the same number is the problem for me, since I have to show this "returned number" to the user.
>
>I am working on how to use the method suggested by Sergey and developed by Craig. It looks, so far, very good. My only concern is that if 6 months later Craig finds a bug in his code (and obviously I won't know about it) I can be potentially stuck with a big problem.
>
>Again, thank you.