There's no such rule. Virtually every internet gateway and mobile payment app lets you key in card numbers to make a charge. There is no encryption in your comp

There's no such rule. Virtually every internet gateway and mobile payment app lets you key in card numbers to make a charge. There is no encryption in your computer's keyboard. The first versions of the headphone jack swipers for phones (i.e. Square) didn't have any kind of encryption either.