Increased security for e-commerce using intelligent card containing several single codes

摘要

During transaction, ID character is transmitted, checked and at the same time an n-th code, not yet marked as invalid, is also transmitted. Then the nth code is marked as invalid. At the next transaction an n+1 th single code is used. Single codes are compared and IC card notes which single code has already been used for a transaction and marks it as invalid. The central office notes that an n-th transaction has been at least attempted. The n-th single code is then marked as invalid. For a subsequent transaction, the next single code i.e. the n+1 th code is used. If a data package with a code of n or less is provided, the transaction is invalid.