Mark of the Beast.
This sure makes it easy to impliment THAT. People aren't going to object when they're so used to the thought of it, especially when introduced slowly for *good* and *benevolent* reasons.
Rev 13: 16 & 17 And he causes all, the small and the great, and the rich and the poor, and the free men and the slaves, to be given a mark on their right hand or on their forehead, and he provides that no one will be able to buy or to sell, except the one who has the mark, either the name of the beast or the number of his name.