The present invention permits a user to conduct remote transactions without
a network while using an untrusted computing device, such as a hand-held
personal digital assistant or a laptop computer. The computing device is
augmented with a smartcard reader, and the user obtains a smartcard and
connects it to the device. This design can be used by an untrusted user to
perform financial transactions, such as placing bets on the outcome of a
probabilistic computation. Protocols are presented for adding (purchasing)
or removing (selling) value on the smartcard, again without requiring a
network connection. Using the instant protocols, neither the user nor the
entity issuing the smartcards can benefit from cheating.
