In my case the smart card is a mandatory government issued ID. [1] I use it to sign more than just banking transactions. Indeed I use it pretty much everywhere

In my case the smart card is a mandatory government issued ID. [1] I use it to sign more than just banking transactions. Indeed I use it pretty much everywhere where classically a pen signature was used. However the concept is more generic than that. Banks could easily supply customers with their own smart cards to do this. Indeed chipped credit cards could be used for this. Although as others have noted, these chipped credit cards still have the classic card numbers printed on them which act as the private key. My local banks also supply chipped credit cards, however you can disable transactions with just the numbers via a checkbox on the bank's website. Surprisingly some banks already disable it by default, so you have to go out of your way to enable transactions with just the numbers. -- [1] https://en.wikipedia.org/wiki/Estonian_ID_card https://en.wikipedia.org/wiki/Estonian_ID_card