| 摘要 |
A system for providing items of value, charging the items to a smart card, and for recharging the smart card. The system includes a station for providing the items of value, which may be postal services, and debiting the cost of the items to a smart card; the smart card being charged with funds equivalent data. The station also communicates with a Data Center for recharging the smart card. Users of the system communicate with the data center to request recharge of a particular smart card and in response to an authorized request the data center generates an encrypted authorization message which includes an identification number, the amount of recharge requested, and control data which preferably includes a control sum formed by adding the amounts stored in a descending register, which stores the amount available on the smart card, and an ascending register which stores the total of the amounts by which the card has been charged since initialization. Thus, the authorization message may be used only once. From time-to-time the Data Center transmits authorization messages to each station on the system. When a particular smart card for which an authorization message has been received is connected to a station, the smart card compares the control data with the control data stored on the smart card and if there is a match updates the funds equivalent data in the descending register of the smart card. To provide security against transmission of false authorization messages to a station, the authorization messages are encrypted, preferably using a public key encryption system.
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