thanks lewek,
i read an article about sony that it's in cour now for "dropping or planting" some "keys" in customers' dvd player/chipset to prevent them from copying the dvd. this has amounted to "tresspassing" or invasion of privacy and has landed them in court. so, this is not legal, even though time-limited shareware are doing it. we can't go that route. and if they can find the key, how can they find it to trace it back to a particular vendor.