| 摘要 |
A smart card is provided with an additional memory (an escrow purse) for electronic cash, which is not accessible to the user. When certain types of transactions are performed - for example, a transaction according to a different electronic cash scheme, or for a particular off-line party - the main card purse is debited, and the escrow purse credited. Thus, a more secure and flexible off-line transaction can be effected. During a transaction with a terminal the smart card determines the cash scheme supported by the terminal, which may be a scheme different from the scheme supported by the operating system of the card. The terminal requests, using the second scheme, a transfer of cash with the smart card and the smart card determines whether the value of cash requested is available in the main purse and only proceeds if the value is available. The smart card debits the value from the main purse, credits the value to the escrow purse, and transfers the value of the cash requested in the second scheme to the terminal. The terminal receives the cash according to the second scheme from the card, the main purse is debited according to the first scheme and a credit of the same value is placed in the escrow purse for later reconciliation.
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