I cannot believe that there digital tv also needs security. But they do need protection (well, aside from bandits and robbers) from unauthorized copying of NTSC/PAL broadcast signals to VCRs. So to avoid this, get a Digital TV Decoder. Digital TV Decords help ensure content management and copy protection management which is a vital step for the film and music industries to openly and confidently release products for digital TV devices.
There are many suppliers or companies where you can buy this from. It is available online or otherwise. Good thing that I have read up regarding this as my husband is preparing himself to buy a digital tv.