'Offline Micropayments without Trusted Hardware' by Matt Blaze.

"(Observe that the online transaction could, in principle, be eliminated if the card holder can be given trusted hardware, such as a smartcard, that maintains its own state about the status of the account and produces signed transaction authorizations). Such systems become extremely vulnerable to fraud and abuse if the online transaction authorization (or the trusted hardware) is eliminated. (For example, consider why few retailers will accept checks from

random customers without verifying their validity with the bank)".

Where are we now??