Check http://www.sweetpotatosoftware.com/SPSBlog/PermaLink,guid,34321a75-a1fc-4a0e-a9af-17a3c6916d90.aspx

>I am thinking about a way to give a rasonable protection to my softwares
>
>As every citizen in brasil have a 11 digit ID number
>
>I would like to create an unlock code based on ID number
>
>For eg.
>
>03281963874
>
>STRAN (123456789, ABCGZHYX4ES)
>
>However it seems simple to guess if the user tries the code
>over and over with other IDs
>
>Is there I function to turn it more complex ?
>
>Regards
>
>Moises