Expenditure Limits in Anonymous Credit Card Systems

Anonymous credit card systems are ones, in which credit card holders can conceal individual transactions from card companies, while enabling card companies to calculate total expenditures of individual cardholders. Although an already proposed mechanism enables card companies also to detect dishonest transaction records, some of them are detected at the end of service periods, and losses caused by this detection delay may grow large to tolerate. To minimize risks caused by dishonest transactions, this paper proposes a mechanism to detect every dishonest transaction record at its occurrence time, and to limit total expenditures of individual cardholders while maintaining anonymity of their transactions.